,illustration3 ,,the ,,thought ,,is ,,in ,,the ,,question ,,the ,,information ,,is ,,in ,,the ,,answer ,,hawkins ,,electrical ,,guide ,,number ,,four ,,questions ,,answers ,,illustrations ,a ,,progressive ,,course ,,of ,,study ,,for ,,engineers1 ,,electricians1 ,,students ,,and ,,those ,,desiring ,,to ,,acquire ,a ,,working ,,knowledge ,,of ,,electricity ,,and ,,its ,,applications ,a ,,practical ,,treatise by ,,hawkins ,,and ,,staff ,,theo4 ,,audel ,,co4 #gb ,,fifth ,,ave4 ,,new ,,york ,,copyrighted1 #aiad1 ,,by ,,theo4 ,,audel ,,co41 ,,new ,,york4 ,printed in the ,united ,states4 ,,table ,,of ,,contents ,,guide ,,no4 #d ,,distribution ,,systems #fig to #gbj ,classification--series system--danger in series arc light system--constant current system--parallel system--arrangement of feeder and mains in parallel system--series-parallel system--center of distribution--,edison three wire system--evolution of the three wire system--balanced three wire system--balancing of three wire system--copper economy in three wire systems--,dobrowolsky three wire system--modifications of three wire system--three wire storage battery system--three wire double dynamo system--three wire bridge system--three wire three brush dynamo system--,dobrowolsky three wire system--three wire auxiliary dynamo system--three wire compensator system--extension of the three wire principle--five wire system--dynamotor--connections of balancing set--balancing coils--distribution by dynamo motor sets--boosters and their uses--auxiliary bus bar4 ,,wires ,,and ,,wire ,,calculation #gba to #gfd ,preliminary considerations--various wires--copper wire--iron wire--,german silver wire--standard of copper wire resistance--relative conductivity of different metals and alloys--conductors--cable for elevator annunciators--covered conductors--rubber covered conductors--rubber insulated telephone and telegraph wires--weather proof conductors--twisted weather proof wires--precautions in using weather proof conductors--slow burning wire2 where used--slow burning weather proof wire2 where used2 how installed--miscellaneous insulated conductors--safe carrying capacity of wire--pothead wires--circular mils--square mils--mil foot--lamp foot--ampere foot--center of distribution--wire gauges--,b4 ,s4 standard wire gauge--micrometer screw gauge--calculating gauge--table of various wire gauges--table of lamp feet for rubber covered wires--lamp table for weather proof wires--symmetrical and unsymmetrical distribution--wiring table for light and power circuits--table of wire equivalents2 how to use--table of cable capacities--incandescent lamps on #ffj watt circuits--tree and modified tree system of wiring--distribution with sub-feeders--wrong and right methods of loop wiring--table1 of amperes per motor2 of amperes per dynamo--calculations for three wire circuit--three wire circuit panel board--size of the neutral wire4 ,,inside ,,wiring #gfe to #gih ,the term wiring--open or exposed wiring--selection of wires--installation--disadvantages of open wiring--splicing--pitch of wires--crossing of wires--wiring across pipes--practical points relating to exposed wiring--methods of carrying wires1 through floors2 on walls--protecting exposed wiring on low ceilings--various porcelain knobs and cleats--wires used in mouldings--standard wooden moulding--kick box--usual character of moulding work--practical points relating to wiring in mouldings--tapping outlets--arc light wiring--arc lamps on low pressure service--circular fixture block--concealed knob and tube wiring2 objections2 method of installation--arrangement of switch and receptacle outlet in knob and tube wiring--switch boxes--rigid conduit wiring2 advantage--types of rigid conduit2 requirements---conduit box--disadvantages of unlined conduit--flexible conduit wiring--,greenfield flexible steel conduit--fishing--insulating point--canopy insulator--fish plug and method of insertion--method of installing conduits in fireproof buildings--service entrance to rubber conduit system--condulet outlet to arc lamp--hickey--methods of bending large conduits--armoured cable wiring2 features2 installation4 ,,outside ,,wiring #gii to #hbd ,materials for outside conductors--tensile strength of copper wire--pole lines--pole constructing tools--wooden poles--preservation of wooden poles--preservation processes--methods of setting wooden poles in unsuitable soil--reinforced concrete poles--cross arms--lineman's portable platform--poles for light and power wires--spacing of poles--erecting the poles--guy anchors--method of raising a pole--method of pulling anchor into place--guys for poles--head and foot guying--guying corner poles--guy stubs and anchor logs--climbers--wiring the line--pay out reels--method of stringing wires--come alongs--tension on wires--sag table--lineman's block and fall with come alongs--attaching wire to insulator--splicing2 ,american wire joint2 ,mc,intire sleeve and sleeve joint--transpositions--insulators--overh ead cable construction--petticoat insulator--,clark's antihum--service connections and loops--method of making series1 and parallel service connections--joint pole crossing--service wires4 ,,underground ,,wiring #hbe to #hdd ,city conditions--underground systems--various conduits--vitrified clay pipe conduit--vitrified clay or earthenware trough conduit--joints in multiple-duct vitrified clay conduit--concrete duct conduits--methods of laying conduit--method of laying single duct vitrified clay conduit--method of laying multiple duct clay conduit--wooden duct conduits--objection to use of wood2 remedy2 adaptation wooden built-in conduits2 method of installation--wrought iron or steel pipe conduits2 method of installation--porcelain bridgework or carriers--cast iron pipe and trough conduit2 advantages--fibre conduits2 joints--,edison tube system--underground cables--metal sheaths on underground cables--pot heads--,general ,electric manhole junction box--pot head connections4 ,,wiring ,,of ,,buildings #hde to #hfd ,preliminary considerations--electrician's instructions--location of receptacles--ceiling buttons--hallway wiring--selection of wiring system--three wire convertible system--method of wiring--location of panel boards--current required on each floor of building--arrangement of feeders--installation of motors--largest size of feeder permissible--method of cutting pocket in floor--outlet baseboard--completed pocket--how to examine partition interiors--house plan of conduit wiring--attachment of mains to knobs--precautions in making joints--wiring for heating appliances--wiring with combination of moulding1 flexible tubing or conduit in non-fire proof building--feeder system for large hotel4 ,,sign ,,flashers #hfe to #hhd ,classification--,carbon flashers--wiring diagram for ,dull's carbon flashers--brush flashers--knife flashers--flasher transmission gearing--simple on and off flashers--flash system of gas lighting--high speed flashers--lighting flashers--wiring diagram for flags--diagram showing method of wiring for high speed effects on single lines--method of wiring for a torch--wiring diagram for high speeds--,dull's lightning--script breakers--chaser flashers--thermo flashers--carriage calls--monogram for carriage calls--wiring diagrams for sign illumination---,national carriage call operating keyboard--clock monogram--,bett's clock mechanism for operating electric monogram time flasher--talking signs--two way thermal flasher4 ,,lightning ,,protection #hhe to #hib ,lightning rods2 why sharp points are used2 erection--diagram showing principle of air gap arrestor--variable gap arc breaker--location of lightning arrestor--carbon arresters with fuses for telephone lines--ground connection4 ,,storage ,,battery #hic to #ifh ,early experiments--theory--description of storage cell--electrolyte--effect of current passing through electrolyte--types of storage batteries--,plant cells--,willard plates2 wood separator--parts of ,autex automobile cells--,faure or pasted type--comparison of ,plant and ,faure plates--the electrolyte2 kind generally used2 preparation2 test2 mixing acid and water2 kind of vessel used2--specific gravity table--effect of deep vessel--density of electrolyte--hydrometer syringe--impurities in electrolyte--tests for impurities2 chlorine1 nitrates1 acetic acid1 iron1 copper1 mercury1 platinum--old electrolyte--voltage of a secondary cell--charging--connections for charging--charging2 first time2 period2 regulation of voltage--,edison cell data--frequency of charging--cadmium test--emergency connections for weak ignition battery--portable testing instruments--charge indications--two methods of charging from a direct current lighting system--colors of the plates--how best results are obtained in charging--charge voltage--two ways of charging--diagram of charging connections--how to keep charging current constant--tests while charging2 after charging--charge indications--behavior of electrolyte during discharge--lead burning outfit--boiling2 causes--hydrogen gas generator for lead burning--quick charging--charging through the night--charging period for new battery--,willard underhung battery box for automobiles--high charging rates--,national instructions for taking voltage readings--mercury arc rectifier--capacity--table of capacity variation for different discharge rates--how to increase the capacity--discharging2 too rapidly rating2 maximum rate--,edison alternating current rectifier--attention after discharging--the battery room--battery attendants--points on care and management--placement of cells--how to avoid leakage--precautions when unpacking cells--assembling cells--connections--precaution in joining terminals--battery troubles--short circuiting2 indication2 location--overdischarge2 buckling--sulphation of plates--data on ,national cells2 ,american cells2 ,autex cells--action in idle cell--lack of capacity--how to prevent lead poisoning--low specific gravity without short circuits2 causes--treatment of weak cells--pole testing paper--disconnecting cells--sulphuric acid specific gravity table--how to take a battery out of commission--,witham charging board--putting batteries into commission--cleaning jars--table of voltage charge as affected by discharge rate--condensed rules for the proper care of batteries4 ,,storage ,,battery ,,systems #ifi to #iif ,uses of storage batteries2 their importance in power plants--load curve showing use of storage battery as aid to the generating machinery--parallel connection of battery and dynamo--floating the battery on the line--diagram showing effect of battery in regulating dynamo load--connections and circuit control apparatus--diagram showing action of battery as a reservoir of reserve power--three wire system with battery and dynamo--methods of control for storage batteries--diagram of connections for ignition outfit--variable resistance--end cell switches--diagram of connection of battery equipment for residential lighting plant--end cell switch diagram--features of end cell switch construction--end cell switch control--circuit diagram for charging battery in two parallel groups and discharging in series--reverse pressure cells2 regulation--,holzer-,cabot dynamotor--boosters--application of series booster system--,bijur's battery system--load diagram--characteristics of series booster--shunt boosters2 with battery--,entz' carbon pile booster system--application of shunt booster--circuit diagram for non-reversible shunt booster and battery system--compound boosters2 their connections--method of charging battery at one voltage and supplying lights at a different voltage--connections of one form of differential booster--differential boosters2 with compensating coil2 adaptation4 ,,chapter ,,xxxvi ,,distribution ,,systems ,the selection of the system of transmission and distribution of electric energy from the generating plant to lamps1 motors1 and other devices1 is governed mainly by the cost of the metallic conductors1 which in many electrical installations1 is a larger item than the cost of the generating plant itself4 ,this is especially true in case of long distance transmission1 while in those of the lighting plants1 the cost of wiring is usually more expensive than that of the boilers1 engines1 and generators combined4 ,the principal distribution systems1 are classed as3 #a4 ,series2 #b4 ,parallel2 #c4 ,series-parallel2 #d4 ,parallel-series4 ,ques4 ,what is the characteristic feature of each class8 ,ans4 ,in the series systems the current is constant1 but the voltage varies4 ,in the parallel systems1 the voltage is constant1 but the current varies4 ,series ,system of ,distribution4--,a series system affords the simplest arrangement of lamps1 motors1 or other devices supplied with electric energy4 ,the connections of such a system are shown in fig4 #ghc4 ,the current from the terminal of the dynamo passes through the lamps1 ,l1 ,l1 ,l1 ,l1 one after the other and finally returns to the terminal4 ,the current remains practically constant1 but the voltage falls throughout the circuit in direct proportion to the resistance1 and the difference in pressure between any two points in the circuit is equal to the current in amperes multiplied by the resistance in ohms included between them4 ,for example4 ,each open arc lamp requires about #ej volts4 ,in the system shown in fig4 #ghc1 the pressure measured across the brushes of the dynamo is assumed to be #a1jjj volts4 ,as this current flows through the circuit #de volts will be actually lost in each lamp1 and as the drop on the line wire is usually about #aj per cent4 of the total voltage1 there will be a drop of #e volts on the conductor between any two lamps4 ,in the circuit shown1 there are twenty lamps1 therefore1 the difference in pressure between either terminal of the dynamo and middle point ,a of the circuit will be #aj lamps #ej volts #ejj volts4 ,likewise1 the difference in pressure between any two points on the circuit will be equal to #ej volts multiplied by the number of lamps included between them4 ,illustration3 ,,fig4 #ghc4--,series system of distribution4 ,this is a constant current system1 so called because the current remains practically constant4 ,it is used chiefly for arc lighting4 ,ques4 ,describe the danger in a series arc light system8 ,ans4 ,since the total voltage of the system is equal to the sum of the volts consumed in all of the lamps1 it is high enough to be dangerous to personal safety4 ,this is illustrated in fig4 #ghc4 ,if the line be grounded at ,b owing to defective insulation1 the pressure of the circuit at that point will be zero1 and therefore1 a man standing on the ground could touch that point without receiving a shock1 but if he should touch the line at the point ,c1 he will receive a slight shock of #aej volts1 as there are three lamps between the point ,c1 and the ground connection ,b4 ,therefore1 the danger of touching the circuit increases directly with the resistance between the point touched and the ground connection1 so that if a man touch the circuit at the point ,d1 he will receive a dangerous shock of #af #ej #hjj volts4 ,in practice1 sixty lamps are often placed on a single arc lighting circuit1 so that its total pressure is about #c1jjj volts1 thus greatly increasing the danger of the system4 ,ques4 ,what is a constant current system8 ,ans4 ,the series system is a constant current system1 and is so called because the current remains practically constant1 while the voltage falls throughout the circuit in direct proportion to the resistance4 ,ques4 ,what are the principal applications of the series system8 ,ans4 ,for arc lighting1 and telegraphic circuits4 ,ques4 ,what are the advantages of the series system8 ,ans4 ,in the case of telegraphic circuits only one wire is required1 and for lighting and power transmission and distribution1 only two wires2 therefore1 it is simpler and cheaper than any other system4 ,ques4 ,what is the disadvantage of the series system8 ,ans4 ,the danger due to the high voltage in installations such as arc lighting circuits4 ,parallel ,system4--,parallel or multiple systems are usually more complicated than series systems1 but since the voltage can be maintained nearly constant by various methods1 practically all incandescent lamps1 electric motors1 and a large proportion of arc lamps are supplied by parallel systems4 ,the general principle of the parallel system is shown in fig4 #ghd4 ,with six lamps on the circuit1 each requiring one-half ampere of current1 at #aaj volts1 the dynamo will have to supply a current of #c amperes at a pressure of #aab volts1 and this current will flow through the circuit and distribute itself as shown on account of the lesser resistance of the wire relatively to that of the lamps4 ,at the first lamp1 the #c amperes will divide1 ampere flowing through the lamp and the remaining #b amperes passing on to the next lamp and so on through the entire circuit4 ,the reduction of pressure from #aab volts across the brushes to #aaj volts at the last lamp is due to the resistance of the conducting wires4 ,ques4 ,what three effects are due to this drop in pressure8 ,ans4 #a1 ,all the lamps or motors in the circuit receive a lower voltage than that at the dynamo1 #b1 some lamps or motors may receive a lower voltage than the others1 and #c1 the voltage at some lamps or motors may vary when the others are turned on or off4 ,illustration3 ,,fig4 #ghd4--,parallel system of distribution4 ,this is a constant voltage system and is used principally for incandescent lighting and electric motor circuits4 ,the first is the least harmful and may be counteracted by running the dynamo at a little higher voltage2 but the second and third are very objectionable and difficult to overcome4 ,they are counteracted successfully in practice1 however1 by various methods of regulation1 the use of boosters1 and the operation of dynamos in parallel4 ,ques4 ,what are the principal applications of parallel or constant pressure systems8 ,ans4 ,they are used on practically all incandescent lamp and electric motor circuits1 and on some arc lamp circuits4 ,ques4 ,why is it specially applicable to incandescent lamp circuits8 ,ans4 ,incandescent lamps cannot be made to stand a pressure much over #bbj volts1 and therefore have to be operated on low voltage systems4 ,ques4 ,what is the principal disadvantage of a parallel system as compared with a series system8 ,ans4 ,the greater cost of the copper conductors4 ,illustration3 ,,fig4 #ghe4--;,arrangement of feeder and mains in parallel system4 ,by locating the feeder at the electrical center1 less copper is required for the mains4 ,the cut does not show the fuses which in practice are placed at the junction of feeder and main4 ,ques4 ,what is the usual arrangement of parallel systems8 ,ans4 ,conductors known as a feeder run out from the station1 and connected to these are other conductors known as a main to which in turn the lamps or other devices are connected as shown in fig4 #ghe4 ,ques4 ,in what two ways may feeders be connected8 ,ans4 ,they may be connected at the same end of the mains1 known as parallel feeding1 or they may be connected at the opposite end of the main1 called anti-parallel feeding4 ,the main may be of uniform cross section throughout1 or it may change in size so as to keep the current density approximately constant4 ,the above condition gives rise to four possible combinations3 #a4 ,cylindrical conductors parallel feeding1 fig4 #ghf2 #b4 ,tapering conductors1 parallel feeding1 fig4 #ghg2 #c4 ,cylindrical conductors1 anti-parallel feeding1 fig4 #ghh2 #d4 ,tapering conductors1 anti-parallel feeding1 fig4 #ghi4 ,illustration3 ,,figs4 #ghf to #ghi4--,various parallel systems4 ,fig4 #ghf1 cylindrical conductors parallel feeding2 fig4 #ghg1 tapering conductors parallel feeding2 fig4 #ghh1 cylindrical conductors anti-parallel feeding2 fig4 #ghi1 tapering conductors anti-parallel feeding4 ,the term tapering is here used to denote a conductor made up of lengths of wire1 each length smaller than the preceding length1 the object of such arrangement being to avoid a waste of copper by progressively diminishing the size of wire so that the relation between circular rails and amperes is kept approximately constant4 ,in an anti-parallel system1 the current is fed to the lamp from opposite ends of the system4 ,series-,parallel ,system4--,this is a combination of the series and parallel systems1 and is arranged as indicated in fig4 #gij4 ,several lamps are arranged in parallel to form a group1 and a number of such sets are connected in series1 as shown4 ,it is not necessary for the groups to be identical1 provided they are all adapted to take the same current in amperes1 which should be kept constant1 and provided the lamps of each set agree in voltage4 ,for example1 on the ordinary #aj-;ampere arc circuit1 one group might consist of #e lamps1 each requiring #b amperes at #ej volts2 the next might be composed of #aj lamps1 each taking #a ampere at #ajj volts1 and so on4 ,illustration3 ,,fig4 #gij4--,series-parallel system of distribution4 ,it consists of groups of parallel connected receptive devices1 the groups being arranged in the circuit in series4 ,parallel-,series ,system4--,in this method of connection1 one or more groups of lamp are connected in series and the groups in parallel as shown in fig4 #gia4 ,illustration3 ,fig4 #gia4--,parallel-series system of distribution4 ,it consists of groups of series connected receptive devices1 the groups being arranged in the circuit in parallel4 ,ques4 ,when is a parallel-series system used8 ,ans4 ,when it is desired to operate a number of lamps or motors on a line where voltage is several times that required to operate a single lamp or motor4 ,the parallel-series system is employed chiefly in the lighting circuit on electric traction lines2 here1 usually five #aaj volt lamps are connected to the source of supply which has a pressure of #eej volts4 ,center of ,distribution4--,it is important to determine the point at which the feeders should be attached to the mains in order to minimize the amount of copper required4 ,the method employed is similar to that used in determining the best location of a power plant as regards amount of copper required4 ,the center of distribution may be called the electrical center of gravity of the system1 and is found by separately obtaining the center of gravity of straight sections and then determining the total resultant and point of application of this resultant of the straight sections4 ,feeders 7feeding cables or conductors7 are run from the source of supply to the distributing centers1 and1 as these feeders are in many cases of considerable length1 a substantial loss of pressure generally occurs in them4 ,the pressure at the source of supply1 however1 is so regulated as to compensate for the drop in the feeders1 and the pressure at the distributing centers is thus kept constant2 or the same result is obtained by the use of regulating devices in the feeders4 ,the essential condition in most systems is that the pressure at the distributing centers shall be kept practically constant1 irrespective of the load4 ,edison ,three ,wire ,system4--,in electric lighting systems used up to about #ahig1 it was not considered practicable to use incandescent lamps requiring a pressure exceeding #abj volts4 ,this limited the operating voltage of parallel systems1 and necessitated the use of conductors of large size and weight1 especially where the current had to be transmitted a considerable distance4 ,the effect of this limiting voltage is more apparent when it is clearly understood that the size of wire required to carry a current depends upon the amperes and not upon the volts4 ,a wire capable of carrying a current of #aj amperes at #bj volts1 can carry #aj amperes at #bj1jjj volts or any other voltage4 ,therefore1 since the amount of electric energy or power transmitted through a conductor is equal to the amperes multiplied by the volts1 it is clear that by increasing the voltage1 the power transmitting capacity of a current can be almost indefinitely increased without increasing the size of the conducting wire4 ,this is the reason why considerations of economy dictate the use of the highest voltages possible in long distance transmissions4 ,the voltage of the current is determined1 however1 by the requirements of the apparatus to be operated4 ,incandescent lamps usually require a pressure of #aaj volts1 and the current required by a #af candle power lamp at that voltage is about ampere4 ,therefore if the lamp be designed for a pressure of #bbj volts1 the current will be reduced to ampere1 and the same size of wire could be used to feed twice as many lamps4 ,illustration3 ,,figs4 #gib and #gic4--;,evolution of the three wire system4 ,fig4 #gib shows two dynamos supplying two independent circuits4 ,these may be connected in series as in fig4 #gic1 thus operating the two circuits of fig4 #gib with two wires instead of four4 ,to balance the system in case of unequal loading1 a third or neutral wire is used as shown in fig4 #gid4 ,the saving of copper is the sole merit of the three wire system1 and the object which led to its invention was to effect this economy with the use of #aaj volt lamps4 ,principle of the ,three ,wire ,system4--,in fig4 #gib1 two dynamos ,a and ,b are shown supplying two independent incandescent lighting circuits1 each circuit receiving #c amperes of current at a pressure of #aaj volts4 ,it is evident that the dynamos could be connected with each other in series1 and the lamps connected in series with two each1 as shown in fig4 #gic1 thus making the two wires ,k and ,l of the two independent circuits unnecessary1 as the pressure will be increased to #bbj volts while the current will remain at #c amperes1 and each lamp will require ampere4 ,illustration3 ,,fig4 #gid4--;,balanced three wire system4 ,the middle conductor1 known as the neutral wire1 keeps the system balanced in case of unequal loading1 that is1 a current will flow through it1 to or from the dynamos1 according to the preponderance of lamps on the one side or the other4 ,these current conditions are shown in fig4 #gig4 ,the amount of copper saved will be #ajj per cent41 but this arrangement is open to the objection1 that when one of the lamps is turned off1 or burned out1 its companion will also go out4 ,this difficulty is avoided in the three wire system by running a third wire ,n1 from the junction ,o1 between the two dynamos1 as shown in fig4 #gid1 thus providing a supply or return conductor to any one of the lamps1 and permitting any number of lamps to be disconnected without affecting those which remain4 ,if the system be exactly balanced1 no current will flow through the wire ,n1 because the pressure toward the - terminal of the dynamo ,a1 will be equal to the pressure from the terminal of dynamo ,b1 thus neutralizing the pressure in the wire4 ,for this reason the middle wire of a three wire system is called the neutral wire1 and is usually indicated by the symbol ,o or the latter meaning that it is positive to the first wire and negative to the second4 ,if the system be unbalanced1 a current will flow through the neutral wire1 to or from the dynamos1 according to the preponderance of lamps in the upper or lower sets4 ,when the number in the lower set is the greater1 the current in the neutral wire will flow from the dynamos as shown in fig4 #gig1 and toward the dynamos under the reverse condition4 ,in the case represented in fig4 #gig1 there are five lamps in circuit1 requiring #b amperes of current at a pressure of #aaj volts4 ,the two lamps in the upper set will require #a ampere1 and the three lamps in the lower set1 #a amperes4 ,since a pressure of #aaj volts can force only a current of one ampere through resistance of the two lamps in the upper set1 it is evident1 that the additional ampere required by the three lamps in the lower set will have to be supplied through the neutral wire1 as shown4 ,balancing of ,three ,wire ,system4--,in practice it is impossible to obtain an exactly balanced system1 as the turning on and off of lamps as required results in a preponderance of lamps in the upper or lower sets1 and furthermore1 even when the number of lamps in the two sets are equal1 they may be located irregularly1 thereby causing the currents to flow for short distances in the neutral line4 ,therefore1 the larger the number of lamps in the circuit1 the easier it will be to keep the system in a balanced condition4 ,copper ,economy in ,three ,wire ,systems4--,theoretically1 the size of the neutral wire has to be only sufficient to carry the largest current that will pass through it4 ,a large margin of safety1 however1 is allowed in practice so that its cross section ranges from about one-third that of the outside line1 in large central station systems1 to the same as that of each outside line in small isolated systems4 ,if the neutral wire be made one-half the size of the outside conductor1 as is usually the case in feeders1 the amount of copper required is #e_/af of that necessary for the two wire system4 ,for mains it is customary to make all three conductors the same size increasing the amount of copper to of that required for the two wire system4 ,illustration3 ,,fig4 #gie4--;,dobrowolsky three wire system with self-induction coil4 ,it consists of an ordinary direct current dynamo1 the armature ,a and pole pieces ,n and ,s of which are shown4 ,a self-induction coil ,d1 is connected to two diametrically opposite points of the winding of the armature ,a4 ,the coil ,d may be carried by and revolve with the armature2 but in the construction represented1 it is stationary1 being connected to the armature winding through the brushes ,,cc1 rings and wires ,,jj4 ,the middle point of the self-induction coil ,d1 is connected to the neutral conductor ,o of the three wire system1 the outside conductors and - being supplied from the brushes ,,bb in the usual manner4 ,the pressure at the terminals of the coil ,d is alternating2 hence the latter1 on account of its self-induction1 does not act as a short circuit to the armature4 ,furthermore1 the inductances of the two halves of the coil ,d being equal1 the pressure of the neutral wire ,o is kept midway between the pressures of the outside wires and -4 ,when the two sides of the system are unbalanced in load1 the difference in current carried in one direction or the other by the neutral wire passes freely through the coil ,d1 since the current is steady1 or varies slowly1 and is therefore unimpeded by the self-induction4 ,it is evident that the ohmic resistance of ,d should be as low and its self-induction as high as possible1 in order that the loss of energy and the difference in voltage on the two sides of the system shall be as small as possible under all conditions4 ,modifications of the ,three ,wire ,system4--,by the employment of suitable arrangements1 it is possible to operate a three wire system with only one dynamo4 ,some of the various arrangements which have been used or proposed in this connection may be briefly mentioned as follows3 ,three ,wire ,storage ,battery ,system1 in which a storage battery is connected between the two outside wires1 and the pressure of the neutral wire varied to balance the system by shifting the point at which it is connected to the battery4 ,three ,wire ,double ,dynamo ,system1 in which a double dynamo having two armature windings upon the same core1 connected to two separate commutators1 is used in the same manner as two separate dynamos connected in series4 ,three ,wire ,bridge ,system1 in which a resistance is connected across the two outside wires1 and the neutral wire is brought to a point on the resistance through a movable switch4 ,the pressures on the two sides of the circuit are equalized by adjusting the arm of the switch for any change of load4 ,illustration3 ,,fig4 #gif4--,three wire compensator system4 ,a and ,b are the compensators or equalizers4 ,they consist of auxiliary dynamos coupled together and connected to the system as shown4 ,d is the main dynamo1 and ,e1 a booster4 ,three ,wire ,three ,brush ,dynamo ,system1 in which the neutral wire is connected to a third brush on the dynamo4 ,dobrowolsky ,three ,wire ,system1 in which a self-induction coil is connected to two diametrically opposite points of the armature of an ordinary direct current dynamo4 ,the principle of this system is illustrated in fig4 #gie4 ,three ,wire ,auxiliary ,dynamo ,system1 in which the neutral wire is connected to an auxiliary dynamo which supplies a pressure one-half as great as that of the main dynamo4 ,the auxiliary dynamo is usually belt driven by the main dynamo1 and acts as a dynamo when the load is greater on the negative side of the circuit1 and as a motor when the excess of load is on the positive side4 ,three ,wire ,compensator ,system1 in which two auxiliary dynamos ,a and ,b called compensators or equalizers1 are coupled together and connected to the system as shown in fig4 #gif4 ,each compensator generates one-half as much pressure as the main dynamo ,d1 and serves to equalize the pressure and the load1 the compensator on the lightly loaded side operating as a motor and driving the other as a dynamo4 ,when the system is exactly balanced1 both compensators run as motors under no load1 therefore1 consume very little energy4 ,in this arrangement only one booster ,e1 is required for both sides of the system1 as the compensators are connected to the outside wires at a point beyond the boosters1 and therefore1 sub-divide the increased difference of pressure equally between the two sides of the system4 ,illustration3 ,,fig4 #gig4--,three wire double dynamo system having two separate windings on the same core and separate commutators ,a and ,b as shown4 ,extension of the ,three ,wire ,principle4--,in order to attain still greater economy in copper1 the principles of the three wire system may be extended to include four1 five1 six1 and seven wire systems4 ,the comparative weights of copper required by such systems are as follows3 ,two wire system #a4jjj ,three all wires of equal size 4#cgj ,three neutral wire one-half size 4#cac ,four all wires of equal size 4#bbb ,five 4#aef ,seven 4#jif ,the four wire system requires about two-ninths as much copper1 and the seven wire system about one-tenth as much copper1 as an equivalent two wire system2 but neither is desirable1 as their operation involves too much inconvenience1 too many unavoidable complications1 and create a possibility of accident1 which more than offsets the saving in copper4 ,illustration3 ,,fig4 #gih4--;,diagram showing dynamotor connections when used as an equalizer in the three wire system4 ,,dm1 dynamotor2 ,g1 generator side2 ,m1 motor side4 ,the ,five ,wire ,system4--,this system is employed advantageously in many places in ,england and ,europe1 but has not as yet been introduced to any extent in ,america4 ,it is very probable that in the future the three wire #ddj volt system will be selected in preference to the five wire system4 ,dynamotor4--,this is a combination of dynamo and motor on the same shaft1 one receiving current and the other delivering current1 usually of different voltage1 the motor being employed to drive the dynamo with a pressure either higher or lower than that received at the motor terminals4 ,the dynamotor in the direct current circuit corresponds to the transformer in the alternating current circuit4 ,illustration3 ,,fig4 #gii4--;,diagram showing connections of balancing set in three wire one dynamo system4 ,the set consists of a motor and dynamo connected1 and its operation is practically the same as a dynamotor4 ,ques4 ,how is the dynamotor used as an equalizer in the three wire system8 ,ans4 ,when thus used1 the machine is connected as in fig4 #gih4 ,when both sides of the system are balanced1 there will be no current in the neutral lead ,n1 and a small current will pass through the two armature windings of the dynamotor in series1 both armatures acting as motors4 ,if the load on one side of the system become larger than the load on the other side1 there will be a greater drop in the leads connected to the overloaded side and consequently a lower voltage will exist over the larger load than exists over the smaller load4 ,the armature winding of the dynamotor connected to the higher voltage will act as a dynamo1 whose pressure will tend to raise the voltage of the more heavily loaded side4 ,the direction of the currents in an unbalanced three wire system that is being supplied with energy from a main dynamo is shown in the figure4 ,the commutator at ,g is connected to the dynamo winding of the dynamotor and is supplying current to the upper or larger load1 and the lower commutator is connected to the motor winding of the dynamotor and is taking current from the lightly loaded side4 ,motor-,dynamo or ,balancing ,set4--,a balancing set or balancer consists of a motor mechanically connected to a dynamo used to balance a three wire system4 ,the operation of such a combination is practically the same as the dynamotor just described4 ,the balancer is connected as shown in fig4 #gii4 ,illustration3 ,,fig4 #hjj4--;,holzer-,cabot type ,m motor-dynamo set4 ,this combination is known as a booster1 and is used to raise or lower the voltage on feeders4 ,the motor is series wound and connected in series with one leg of the feeder4 ,thus1 the voltage which the booster will add to the line will be directly in proportion to the current flowing in the feeder4 ,the regulation is therefore automatic4 ,when an unbalanced load comes on1 the voltage on the lightly loaded side rises and on the heavily loaded side drops4 ,the machine on the light side then takes power from the line and runs as a motor driving the machine on the heavy side as a dynamo1 supplying the extra current for that side4 ,this action tends to bring the voltage back to normal and gives good regulation4 ,in some cases the field of each machine is connected to the opposite side of the system which gives a quicker action4 ,this regulation is automatic and the set takes care of unbalanced loads in either direction without adjustment4 ,balancing ,coils4--,another method of balancing a three wire system which does away with any additional rotating machines makes use of balance coils4 ,ques4 ,describe the type of dynamo used with balancing coils8 ,illustration3 ,,fig4 #hja4--;,diagram showing connections of balancing coil system4 ,the dynamo used in this system is provided with both commutator and collector rings4 ,ans4 ,the regular two wire dynamo is used supplying power to the outside wires1 but there are collector rings connected to the armature4 ,these rings are much lighter than they would be for a converter as they carry only about of the dynamo load4 ,these rings being light are usually placed at the end of the commutator and are connected directly to the commutator bars4 ,ques4 ,how are the balancing coils constructed8 ,ans4 ,they are built of standard transformer parts1 and are placed in cases similar to those of ordinary small transformers4 ,illustration3 ,,figs #hjb and #hjc4--;,distribution by dynamo-motor sets4 ,fig4 #hjb1 sets in parallel2 fig4 #hjc1 sets in series4 ,in fig4 #hjb1 current produced by the main dynamo ,g1 is carried to the machines by the conductors ,a and ,b to which the motor portions ,m are connected in parallel4 ,these motors are provided with shunt wound field coils which may be connected to the primary or to the secondary circuit1 consequently the machines run at a practically constant speed4 ,the dynamo portions ,d of the transformers are connected to the secondary circuits which supply the lamps1 etc41 ,l1 as indicated4 ,the field magnets of these dynamos may also be fed by the main circuit ,,ab1 or they may be self-excited by shunt or compound winding4 ,in fig4 #hjc1 the motors ,m are all connected in series with the main dynamo ,g1 and the dynamo elements ,d of the transformers1 connected to the lamps1 etc41 ,l4 ,if the current be kept constant 7the dynamo ,g having a regulator like a series arc dynamo71 and the motors ,m are simple series wound machines1 they will exert a certain torque1 or turning effort1 which will be constant4 ,it follows1 therefore1 that if the dynamos ,d be also series wound1 each will generate a certain current which will be constant4 ,if lamps or other devices1 designed for that particular current1 be connected in series on the secondary circuits1 the dynamos ,d will always maintain that current1 no matter how many lamps there may be4 ,when lamps are added1 the resistance of the local circuit is raised1 and the current in it decreases1 so that the dynamo increases its speed until it generates sufficient pressure to produce practically the same current as before4 ,hence this constitutes a system which is self-regulating1 when lamps1 etc41 are cut in or out of the secondary circuits4 ,no harm results even if the secondary be short circuited1 since only the normal current can be generated4 ,but if the secondary circuit be opened1 then the machine will race1 and probably injure itself by centrifugal force1 because the torque of the motor ,m has its full value1 and there is no load upon the dynamos ,d4 ,to guard against this danger1 some automatic device should be provided to short circuit the field or armature of the motor when its speed or reverse voltage rises above a certain point4 ,the coil has a straight continuous winding1 both ends and a connection from the middle point of the winding being brought out of the case4 ,ques4 ,how are the coils connected to the dynamo8 ,ans4 ,two coils are used and are connected to the collector rings as shown in fig4 #hja1 one coil across each phase4 ,the connections from the middle points of the coils are connected together and to the neutral wire of the system4 ,illustration3 ,,fig4 #hjd4--;,diagram to show correctness of balancing coil connection4 ,in the figure1 ,,ae1 ,,bf1 ,,cg1 and ,,dh represent the balance coil and its connection for different positions of the armature of a bipolar machine4 ,ques4 ,what is the action of the coils in equalizing the load8 ,ans4 ,on balanced load1 the coils take a small alternating exciting current from the collector rings as any transformer does when connected to an alternating current line with its secondary open4 ,when an unbalanced load comes on1 the current in the neutral divides1 half going to each coil4 ,this enters the coil at the middle point and half flows each way through the coil and the slip rings into the armature winding4 ,the unbalanced current is thus fed back directly into the dynamo armature continuously4 ,the coils are small and can be placed back of the switchboard or below the floor1 as they require no attention4 ,the current flowing to each slip ring is #be of the direct current in the neutral wire with the small exciting current taken by the coil added4 ,the coils are usually built to take care of current in the neutral equal to #be of full load current of the dynamo with a voltage regulation not to exceed #b per cent4 ,ques4 ,upon what does the operation of the balancing coil system depend8 ,ans4 ,it depends on the following points3 ,first1 the impedance#a of the coils keeps the exciting current which they take from the collector rings down to a small value as it is alternating current4 ,at the same time the current from the neutral wire flows through the four half coils in parallel1 and being direct current is impeded only by the ohmic resistance of the coils1 which is low1 giving only a slight loss in the coils4 ,the common point to which the neutral wire is connected must at all times be neutral to the - and direct current brushes4 #a ,,note4--,the term impedance means the total opposition in an electric circuit to the flow of an alternating current1 being made up of the actual or ohmic resistance and the apparent resistance due to self-induction1 or if the circuit contain also capacity1 the resultant apparent resistance due to self-induction and capacity4 ,that this common point is at all times neutral is readily shown4 ,referring to fig4 #hjd1 let ,,ae1 ,,bf1 ,,cg and ,,dh represent the balance coil and its connection for different positions of the armature of a bipolar machine4 ,let ,o be the tap to the middle point of the winding4 ,take the instant when the balance coil taps are directly under the direct current brushes as shown at position ,,ae4 ,it is evident that since the point ,o is the middle point of the coil1 it is neutral between ,a and ,e4 ,when the armature turns so that the balance coils take the position ,,bf1 the voltage drop between ,a and ,e may be divided into #d parts1 ,,ab1 ,,bo1 ,,of and ,,fe4 ,as in the first instance1 ,o is neutral between the ends of the coil1 and the voltage drop over ,,of equals that over ,,ob4 ,since the space ,,ab includes the same number of armature coils as space ,,fe and they are in fields of equal strength1 the voltages across the two spaces will be equal1 and the voltage over ,,ab equals that over ,,fe4 ,then adding equals3 ,,ab ,,bo ,,fe ,,fo and ,o is neutral between ,a and ,e as in the first case4 ,in the same way it can be shown that ,o is neutral between the direct current brushes for any position of the balance coil taps4 ,one coil will operate the system1 but two coils1 giving four points spaced #ij electrical degrees apart1 give better distribution of the current to the armature winding and better regulation of the voltage4 ,boosters4--,a booster may be defined as1 a dynamo inserted in a circuit at a point when it is necessary to change the voltage4 ,a booster is generally driven by a motor1 the two armatures being directly coupled1 although boosters are sometimes driven from the engine or line shaft4 ,illustration3 ,,fig4 #hje4--;,crocker ,wheeler motor-dynamo set4 ,there are numerous cases where such a combination is useful for furnishing a circuit with a voltage different from that of the main plant or with a voltage that can be varied independently4 ,for storage battery charging and electrolytic work1 where constant current is desirable1 it forms a simple means of voltage regulation4 ,where a circuit of special voltage is required1 the set not only supplies current at the desired pressure1 but insulates the special circuit1 which may be subject to more severe requirements than the main system4 ,the advantage of the three wire distribution can be obtained from any two wire dynamo by means of a small rotary balancer or balancing transformer1 which consists of two direct current machines of the same voltage1 mechanically connected together with their armatures in series4 ,multiple voltage systems for speed regulation can also be obtained by a similar arrangement4 ,ques4 ,explain the use of a booster8 ,ans4 ,when a number of feeders run out from a station1 the longest and those carrying the heaviest loads will have so much drop on the line that the pressure at distant points is too low4 ,it is therefore necessary to raise the pressure to compensate for the drop and this is done by inserting a booster in the circuit4 ,it would not be economical to raise the voltage on all the lines by supplying current from the main dynamo at higher pressure1 hence the voltage is raised only on the lines which need it by means of the booster working in series with the main dynamo4 ,illustration3 ,,fig4 #hjf4--;,diagram showing use of auxiliary bus bar4 ,in order to avoid the necessity for boosters1 some stations have an extra bus bar1 which is kept at a higher pressure than the main bus1 and to this are connected the feeders that have an extra large drop4 ,ques4 ,for what other service are boosters employed8 ,ans4 ,they are used in connection with storage battery plants for the purpose of raising the voltage of the bus bars to the pressure necessary for charging storage batteries4 ,ques4 ,what is an auxiliary bus bar8 ,ans4 ,an extra bus bar which is kept at higher pressure than the main bar4 ,ques4 ,what is the object of an auxiliary bus bar8 ,ans4 ,it is used in place of a booster as shown in fig4 #hjf4 ,one or more dynamos maintain the pressure between the auxiliary bar and the common negative bar4 ,the feeders which need boosting are connected to the common negative bar and the auxiliary bar as shown4 ,,chapter ,,xxxvii ,,wires ,,and ,,wire ,,calculations ,the wireman who is called upon to plan and install a system of wiring will find it necessary first to have a knowledge of the various kinds of wire so as to select the one best suited for the work1 and to be able to make simple calculations in order to determine the proper sizes of wire for the various circuits4 ,wires are generally made of circular cross section4 ,the process of manufacture consists in drawing the material through steel dies1 when its properties permit this treatment4 ,in the case of some substances1 as for instance1 tin and lead1 difficulties arise in the drawing process1 and these are therefore squirted4 ,the metals most extensively used for wires are copper and iron2 ,german silver1 tin and lead are also employed1 but only at points where it is desirable to have a comparatively high resistance in the circuit4 ,copper ,wire4--,copper is used in nearly all cases of wiring because it combines high electrical conductivity with good mechanical qualities and reasonable price4 ,in conductivity it is only surpassed by silver1 but the cost of the latter of course prohibits its use for wiring purposes4 ,copper wire is used for electric light and power lines1 for most telephone and some telegraph lines1 and for all cases where low resistance is required at moderate cost4 ,hard drawn copper wire is ductile1 and has a high tensile strength2 these properties allow it to be bent around corners and drawn through tubes without injury4 ,pure annealed copper has a specific gravity of #h4hi at #fj ,fahr4 ,one cubic inch weighs 4#cb pound2 its melting point is about #b1ajj ,fahr4 ,good hard drawn copper has a tensile strength of about three times its own weight per mile length4 ,thus1 a number #aj ,b4 ,s4 gauge copper wire1 weighing #aff lbs4 per mile1 will have a breaking strength equal to approximately #c #aff #dih lbs4 ,iron ,wire4--,this kind of wire is largely used for telegraph and telephone lines1 although it is rapidly being replaced by copper in long lines4 ,there are three grades of iron wire3 #a4 ,extra best best 7,e4 ,b4 ,b47 which has the highest conductivity and is the nearest to being uniform1 in quality1 being both tough and pliable2 #b4 ,best best 7,b4 ,b471 which varies more in quality1 is not so tough1 and is lower in conductivity4 ,it is frequently sold as ,e4 ,b4 ,b42 #c4 ,best 7,b471 which is the poorest grade made1 being more brittle1 and lowest in conductivity4 ,iron wire should be well galvanized4 ,german ,silver ,wire4--,german silver is an alloy consisting of #ah to #cj nickel1 and the balance about four parts copper to one part zinc4 ,it is very largely used as a resistance material in making resistance coils1 and is sold in the form of wire1 and strip4 ,the resistance of this wire varies with its composition4 ,the resistance of the #ah alloy at #be ,c4 is #ah times that of copper1 and of the #cj alloy about #bh times that of copper4 ,the safe carrying capacity of the wire in spirals in open air for continuous duty is such that the circular mils per ampere varies from about #a1ejj in ,no4 #aj wire to about #dge in ,no4 #cj4 ,for intermittent duty the capacity is twice as great4 ,standard of ,copper ,wire ,resistance4--,matthiessen's standard for resistance of copper wire is as follows3 ,a hard drawn copper wire one meter long1 weighing one gramme1 has a resistance of 4#adfi ,b4 ,a4 unit at #cb ,fahr4 ,relative conducting power3 silver1 #ajj2 hard or un-annealed copper1 #ii4ie2 soft or annealed copper1 #ajb4ba4 ,a committee of the ,am4 ,inst4 ,electrical ,engineers recommends the following form of ,matthiessen's standard1 taking #h4hi as the specific gravity of pure copper3 ,a soft copper wire one meter long and one millimeter in diameter has an electrical resistance of 4#jbjeg ,b4 ,a4 unit at #j;,c4#b ,from this the resistance of a soft copper wire one foot long and 4#jja in4 in diameter 7mil-foot7 is #i4gb ,b4 ,a4 units at #j;,c4 #b ,,note4--,the international ohm ,b4 ,a4 ohm #a 4#ihff4 ,the ,b4 ,a4 ohm ,international ohm #a #a4jacf4 ,hence1 to reduce ,british ,association ohms to ,international ohms1 divide by #a4jacf4 or multiply by 4#ihff4 ,for every degree ,fahr41 the resistance of copper wire increases 4#bbbb4 ,thus a piece of copper wire having a resistance of #aj ohms at #cb1 would have a resistance of #aa4aa ohms at #hb4 ,relative ,conductivity of ,different ,metals and ,alloys4 7,according to ,lazare ,weiler47 ,pure silver #ajj ,pure copper #ajj ,alloy1 copper1 silver #hf4fe ,telephonic siliceous bronze #ce ,pure zinc #bi4i ,brass with #ce zinc #ba4e ,swedish iron #af ,pure platinum #aj4f ,copper with #aj nickel #aj4f ,pure lead #h4hh ,pure nickel #g4hi ,phosphor-bronze1 #aj tin #c4hh ,conductors4--,copper is used more than any other metal for transmitting electrical energy1 and for interior wiring it is used exclusively4 ,copper conductors should be of the highest commercial conductivity1 not less than #ig4 ,for conductors up to sizes as large as ,no4 #h ,b4 ,s4 gauge1 single conductors may be used1 but for larger sizes the necessary conductivity should be obtained by conductors made up of strands of smaller wires4 ,the size of these strands depend upon the size of the conductors and the conditions under which they are to be used4 ,where conductors are very large 7as for instance dynamo leads71 and where it is essential that they should be as flexible as possible1 strands as small as ,no4 #bj or #bb ,b4 ,s4 gauge may be used4 ,conductors for flexible cords1 pendants1 fixtures1 etc41 should also consist of very fine strands1 so that they may be perfectly pliable and flexible4 ,the individual strands for instance1 for a ,no4 #af ,b4 ,s4 gauge flexible cord should be as fine as ,no4 #cj4 ,illustration3 ,,fig4 #hjg4--;,elevator cable for annunciators4 ,this type of cable is designed for connecting the movable elevator car with the signal buttons upon the different floors1 and is constructed so as to secure strength and flexibility4 ,covered ,conductors4--,for most conditions of service1 wires are protected with an insulating covering4 ,wires used in interior circuits should have a covering which shall act both as an electrical insulator and as a mechanical protection4 ,in some instances1 however1 the insulating qualities are of secondary importance4 ,the various forms of covering now in use commercially for wires are3 #a4 ,rubber2 #b4 ,weather proof2 #c4 ,slow burning2 #d4 ,slow burning weather proof2 #e4 ,armoured4 ,rubber ,covered ,conductors4--,this class of conductor consists of a tinned copper wire with a rubber covering1 protected by an outside braiding of cotton saturated with a preservative compound4 ,ques4 ,what are the advantages of rubber insulation for conductors8 ,ans4 ,it is waterproof1 flexible1 fairly strong1 and has high insulating qualities4 ,illustration3 ,,fig4 #hjh4--,rubber insulated telephone and telegraph wires4 ,the inner coat of rubber should be free from sulphur or other substances liable to corrode the copper4 ,ques4 ,what are the disadvantages of rubber insulation8 ,ans4 ,it deteriorates more or less rapidly and is quickly injured by temperatures above #adj ,fahr4 ,ques4 ,for what service are rubber covered conductors adapted8 ,ans4 ,for interior wiring4 ,ques4 ,is pure rubber used8 ,ans4 ,no4 ,the covering should be made from a compound containing from #bj to #ce per cent4 of pure rubber4 ,it would be difficult to place pure rubber on a wire1 and moreover a covering made of pure rubber would not be durable and would deteriorate very rapidly1 particularly at temperatures above #abj ,fahr4 ,accordingly1 it is mixed with other materials1 such as ,french chalk1 silicate of magnesia1 sulphur1 red lead1 etc4 ,weather ,proof ,conductors4--,in this class of conductor1 the wire is protected from the weather by a waterproof covering1 consisting usually of braided cotton of two or three thicknesses saturated with a moisture resisting insulating compound4 ,ques4 ,where are weather proof conductors used8 ,ans4 ,in places subject to dampness1 such as cellars1 tunnels1 open sheds1 breweries1 etc4 ,illustration3 ,,fig4 #hji4--,twisted weather proof wires4 ,the insulation consists of two or three thicknesses of braided cotton saturated with a moisture resisting insulating compound4 ,ques4 ,what are the advantages of weather proof conductors8 ,ans4 ,the insulation is cheap1 very durable1 and does not deteriorate unless exposed to high temperatures such as will melt the compound4 ,ques4 ,state the disadvantages4 ,ans4 ,the covering is more or less inflammable and is not very efficient as an insulator4 ,ques4 ,what precaution should be taken in using weather proof conductors8 ,ans4 ,on account of the inflammable character of the covering1 care should be taken in wiring at points where any considerable number of conductors are brought together1 or where there is much woodwork or other combustible material4 ,ques4 ,for what use are weather proof conductors especially adapted8 ,ans4 ,for outside wiring where moisture is certain and where fireproof quality is not necessary4 ,obviously conductors of this class should not be used in conduits1 nor in fact1 in any way except exposed on glass or porcelain insulators4 ,slow ,burning ,wire4--,this class of conductor is defined as3 one that will not carry fire4 ,the covering consists of layers of cotton or other thread1 all the interstices of which are filled with the fireproofing compound1 or of material having equivalent fire resisting and insulating properties4 ,the outer layer is braided and specially designed to withstand abrasion4 ,the thickness of insulation must not be less than that required for slow burning weather proof wire and the outer surface must be finished smooth and hard4--,underwriters' requirements4 ,illustration3 ,,fig4 #haj4--,slow burning wire1 formerly known as ,underwriter's ,wire4 ,the insulation is triple braided1 saturated with a white fireproof compound4 ,solid conductor4 ,ques4 ,where should slow burning wires be used8 ,ans4 ,in hot dry places1 where ordinary insulations would be injured1 and where wires are bunched1 as on the back of a large switchboard or in a wire tower4 ,a slow burning covering is considered good enough when the wires are entirely on insulating supports4 ,its main object is to prevent the copper conductors coming into contact with each other or anything else4 ,ques4 ,what must be done before using weather proof wire8 ,ans4 ,permission to use the wire must first be obtained from the local ,inspection ,department4 ,slow ,burning ,weather ,proof ,wire4--,the covering of this type wire is a combination of the underwriters and weather proof insulations4 ,the fireproof coating comprises a little more than half of the total covering4 ,when the fireproof coating is placed on the outside1 the wire is called slow burning weather proof4 ,illustration3 ,,fig4 #haa4--,slow burning weather proof wire4 ,the insulation is composed of two braids thoroughly saturated with a fire proof composition1 over which is a highly polished weather proof third braid4 ,this wire was formerly known as fire and weather proof wire4 ,ques4 ,how does slow burning weather proof wire compare with weather proof wire8 ,ans4 ,it is less inflammable and less subject to softening under heat4 ,ques4 ,where should slow burning weather proof wire be used8 ,ans4 ,in places where the wires are to be run exposed and where moisture resisting quality is desired1 also where at the same time it is desirable to avoid an excess of inflammable covering4 ,ques4 ,how should it be installed8 ,ans4 ,it should be set on glass or porcelain insulators4 ,miscellaneous ,insulated ,conductors ,illustration3 ,,fig4 #hab4--;,armoured submarine cable4 ,this type of cable is insulated with a rubber compound containing not less than #cj of pure ,para rubber4 ,the following specifications have been adapted by various telegraph companies and the ,united ,states ,government for general use4 ---------------------------------------- ---------------------------------------- ---------------------------------------- --------------- ,no4 of ,gauge of ,no4 of ,gauge of ,outside ,weight ,conductors ,conductors ,armour ,armour ,wires ,diameter per #a1jjj 7,b4 ,s47 ,wires ,b4 ,w4 ,g4 7inch7 ,feet ---------------------------------------- ---------------------------------------- ---------------------------------------- --------------- #a #ad #ab #h #a1aej #b #ad #af #h #a-ca_/cb #a1fge #c #ad #ad #f #a #b1djj #d #ad #af #f #a-e_/af #b1gej #e #ad #ai #f #a #c1ajj #f #ad #ba #f #a #c1ejj #g #ad #ba #f #a #c1fjj #aj #ad #bb #d #a #d1fjj ---------------------------------------- ---------------------------------------- ---------------------------------------- --------------- ,,note4--,the above specifications refer only to river and harbor cables4 ,ocean cables are of an entirely different character1 and consist of shore end1 intermediate and deep sea types4 ,illustration3 ,,fig4 #hac4--;,gas engine ignition cable4 ,this is a special cable made to stand the hard service necessary on automobiles4 ,the conductor is composed of #cf strands of ,no4 #bg tinned copper wire1 equal to ,no4 #ad in capacity1 which gives it necessary flexibility4 ,about this conductor are woven two layers of cotton thread4 ,over this are woven1 in opposite directions1 several layers of specially prepared tape which has been given two coatings of fine insulating varnish4 ,two strong braids of cotton form the outside covering1 and each of these different braids is passed through a bath of insulating liquid and baked in a steam heated oven4 ,with three layers of tape the cable will stand a test of #ah1jjj to #bj1jjj volts1 and with five layers1 #cj1jjj volts4 ,illustration3 ,,fig4 #had4--,paper insulated lead encased telephone cable4 ,ques4 ,for what service is slow burning weather proof wire not suited8 ,ans4 ,it is not adapted to outside work4 ,safe ,carrying ,capacity of ,wire4--,all wires will heat when a current of electricity passes through them4 ,the greater the current or the smaller the wire1 the greater will be the heating effect4 ,large wires are heated comparatively more than small wires because the latter have a relatively greater radiating surface4 ,illustration3 ,,fig4 #hae4--,pothead wires4 ,the standard wire for pothead work is either ,no4 #ai1 #bj or #bb ,b4 ,s4 gauge1 either single conductor or twisted pair1 insulated to a diameter of #c_/cb inch over rubber1 without any outer braid or protection4 ,in the case of twisted pairs one conductor is usually made of a differently colored rubber than the other1 so as to distinguish between them4 ,the temperature of a wire increases approximately as the square of the current1 and inversely as the cube of the diameter of the wire4 ,the elevation in temperature of a wire carrying a current represents so much lost energy4 ,from these considerations it must be clear that it is important not to overload conductors in order to secure efficient working1 and to avoid risk of fire on inside installations4 ,the ,board of ,underwriters specifies that the carrying capacity of a conductor is safe when the wire will conduct a certain current without becoming painfully hot4 ,in the following table of carrying capacity1 prepared by the underwriters1 a wire is assumed to have a safe carrying capacity when its temperature is not increased by the given current over #cj ,fahr4 above that of the surrounding air4 ,,safe ,,carrying ,,capacities ,,of ,,wires 7,maximum amperes allowed by the ,underwriters47 ---------------------------------------- ---------------------------------------- ------------- ,brown ,rubber ,other and insulation insulations ,sharpe ,circular mils ------------ ------------ ,gauge ,amperes ,amperes ---------------------------------------- ---------------------------------------- ------------- #ah #a1fbd #c #e #af #b1ehc #f #h #ad #d1ajg #ab #af #ab #f1ecj #ag #bc #aj #aj1chj #bd #cb #h #af1eaj #cc #df #f #bf1bej #df #fe #e #cc1ajj #ed #gg #d #da1gdj #fe #ib #c #eb1fcj #gf #aaj #b #ff1cgj #ij #aca #a #hc1fij #ajg #aef #j #aje1ejj #abg #ahe #jj #acc1ajj #aej #bbj #jjj #afg1hjj #agg #bfb #jjjj #baa1fjj #baj #cab #bjj1jjj #bjj #cjj #cjj1jjj #bgj #djj #djj1jjj #ccj #ejj #ejj1jjj #cij #eij #fjj1jjj #dej #fhj #gjj1jjj #ejj #gfj #hjj1jjj #eej #hdj #ijj1jjj #fjj #ibj #a1jjj1jjj #fej #a1jjj #a1ajj1jjj #fij #a1jhj #a1bjj1jjj #gcj #a1aej #a1cjj1jjj #ggj #a1bbj #a1djj1jjj #haj #a1bij #a1ejj1jjj #hej #a1cfj #a1fjj1jjj #hij #a1dcj #a1gjj1jjj #icj #a1dij #a1hjj1jjj #igj #a1eej #a1ijj1jjj #a1jaj #a1faj #b1jjj1jjj #a1jej #a1fgj ---------------------------------------- ---------------------------------------- ------------- ,the lower limit is specified for rubber covered wires to prevent gradual deterioration of the high insulations by the heat of the wires1 but not from fear of igniting the insulation4 ,the question of drop is not taken into consideration in the table on page #gca4 ,the carrying capacity of ,nos4 #af and #ah ,b4 ,s4 gauge wire is given1 but no smaller than ,no4 #ad is to be used1 except as allowed under rules for fixture wiring4--,underwriters' ,rules4 ,circular ,mils4--,the unit of measurement in measuring the cross sectional area of wires is the circular mil2 it is the area of a circle one mil 74#jja in47 in diameter4 ,the area of a wire in circular mils is equal to the square of the diameter in mils4 ,illustration3 ,,fig4 #haf4--;,diagram illustrating circular mils4 ,the circular mil is used as a unit of cross sectional area in measuring wires4 ,it is equal to the area of a circle 4#jja in4 diameter2 its value is 4#jjjjjjghed square inch4 ,in the figure the sum of the areas of the nine small circles equals the area of the large circle4 ,this is evident from the following3 ,take the diameter of the small circles as unity1 then the diameter of the large circle is three4 ,hence1 the sum of the area of the small circles 7 #a7 #i 4#ghed #i #g4jfhf2 area of the large circle #c 4#ghed #i #g4jfhf4 ,therefore since the area of the large circle equals the sum of the areas of the small circles1 the area of a wire in circular mils is equal to the square of its diameter expressed in mils4 ,thus a wire #b mils in diameter 74#jjb in47 has a cross sectional area of #b #b circular mils4 ,accordingly to obtain the area of a wire in circular mils1 measure its diameter with a micrometer which reads directly in mils or thousandths of an inch1 and square the reading4 ,the circular mil 7abbreviated ,c4,m47 applies to all round conductors1 and has a value of 4#ghed times that of the square mil1 that is1 #a circular mil 4#ghed square mil4 ,if the diameter be expressed as a fraction of an inch1 as for instance in41 the circular mil area may be found as follows3 ,reduce the fraction to the decimal of an inch1 multiply the result by #a1jjj to express the diameter in mils1 and square the diameter so expressed1 thus3 #a1jjj #c 4#ccc4 4#ccc #a1jjj #ccc mils2 #ccc #ccc #aaj1hhi circular mils4 ,the diameter of any wire may be found when its circular mil area is known by extracting the square root of the circular mil area4 ,square ,mils4--,for measuring conductors of square or rectangular cross section1 such as bus bars1 copper ribbon1 etc41 the square mil is used4 ,a square mil is the area of a square whose sides are one mil 74#jja in4 long7 and is equal to 4#jja 4#jja 4#jjjjja square inch4 ,illustration3 ,,fig4 #hag4--;,diagram illustrating square mils4 ,a square mil is a unit of area employed in measuring the areas of cross sections of square or rectangular conductors4 ,it is equal to 4#jjjjja square inch4 ,one square mil equals #a4bgcb circular mils4 ,the figure shows an area of nine square mils2 this is equal to #i #a4bgcb #aa4dehh circular mils4 ,,example4--,a copper ribbon for a field coil measures inch by inch4 ,what is its area in square mils8 ,what is its area in circular mils8 4#fbe in41 or #fbe mils2 4#abe in41 or #abe mils4 ,area in square mils #fbe #abe #gh1abe4 ,area in circular mils #gh1abe 4#ghed or #gh4abe #a4bgcb #ii1dfi4 ,mil ,foot4--,this unit is used as a basis for computing the resistance of any given wire4 ,a mil foot means a volume one mil in diameter and one foot long4 ,the resistance of a wire of commercially pure copper one mil in diameter and one foot long is taken as a standard in calculating the resistance of wires1 and has been found to be equal to #aj4gi ohms at #ge ,fahr4 ,the calculation is made according to the following rule3 ,the resistance of a copper wire is equal to its length in feet1 multiplied by the resistance of one mil foot 7#aj4gi ohms7 and divided by the number of circular mils1 or the square of its diameter4 ,expressed as a formula3 length of wire in ft4 #aj4gi resistance in ohms ---------------------------------------- -------------------- 7#a7 circular mils ,,example4 ,what is the resistance of a copper wire #a1ejj feet long and having a transverse area of #aj1cha circular mils8 ,substituting these values in formula 7#a7 #a1ejj #aj4gi resistance ---------------------------------------- #a4eei ohms4 #aj1cha ,the transverse area of a copper wire is found by multiplying the resistance of a mil foot 7#aj4gi7 by its length in feet and dividing the result by its resistance in ohms4 ,this is obtained directly from the formula 7#a7 by solving the equation for circular mils1 thus3 length of wire in ft4 #aj4gi circular mils ---------------------------------------- --------------------- 7#b7 resistance in ohms ,,example4 ,what is the circular mil area of a wire #a1ejj feet long and having a resistance of #a4eei ohms8 ,substituting the values in equation 7#b7 #a1ejj #aj4gi circular mils ------------------------- #aj1cha #a4eei ,illustration3 ,,figs4 #hah and #hai4--;,diagrams illustrating the meaning of the term lamp foot1 and how to apply it in calculating a circuit4 ,as defined1 one #af candle power lamp at a distance of one foot from the fuse block or point of supply is called a lamp foot2 this is equivalent to one #h candle power lamp at a distance of #b feet1 or one #cb candle power lamp one-half foot from the fuse block4 ,in fig4 #hai1 there are four #h candle power lamps1 and the distance to center of distribution is #aj feet4 ,the circuit then contains #d #b #aj #bj lamp feet4 ,lamp ,foot4--,this unit facilitates laying out wiring and calculating the drop4 ,a lamp foot is defined as one #af candle power lamp at a distance of one foot from the point of supply4 ,accordingly the number of lamp feet in any circuit is equal to the number of #af candle power lamps 7or equivalent in other sizes7 in the circuit multiplied by the distance in feet from the fuse block to the center of distribution4 ,when no point is specified1 the feet are always measured from the supply point to the center of distribution4 ,when other than #af c4p4 lamps are in the circuit they must be reduced to #af c4p4 lamps4 ,thus two #h c4p4 lamps would be counted one #af c4p4 lamp1 one #cb c4p4 lamp would be counted two #af c4p4 lamps1 etc4 ,ampere ,foot4--,from the foregoing explanation of lamp foot1 the significance of ampere foot is easily understood--the two terms are in fact self-defining4 ,an ampere foot may be defined as the product of one ampere multiplied by one foot4 ,the unit ampere foot is used in figuring motor circuits or currents designed to carry a mixed load4 ,illustration3 ,,fig4 #hbj4--,the center of distribution of a circuit coincides with the geometrical center of the group of lamps when the lamps are of uniform size and spaced equal distances apart4 ,the center of distribution is here indicated by the dotted line ,a ,b4 ,the ampere feet of a main are found by multiplying the maximum load in amperes by the distance from the fuse block to the electrical center of the load4 ,thus if the center of distribution be #ej feet from the fuse block and the maximum load is #i amperes1 the number of ampere feet is equal to #i #ej #dej4 ,electrical ,center of ,distribution4--,the electrical center of a circuit depends upon the distances between the lamps and the fuse block2 also the relative sizes of the lamps4 ,it may be defined as the sum of the lamp feet for each section divided by the number of #af candle power lamps in the circuit4 ,if the lamps be of uniform capacity1 and placed at equal distances apart1 the center of distribution will coincide with the geometrical center of the group of lamps4 ,however1 if the lamps vary in size1 and be irregularly spaced1 the electrical center will not coincide with the geometrical center unless the lamps be symmetrically arranged so as to compensate for the difference in sizes and spacing4 ,illustration3 ,,fig4 #hba4--;,diagram of an irregular circuit illustrating method of finding the center of distribution4 ,rule3 ,divide the sum of the lamp feet for each section by the number of #af candle power lamps or equivalent in the circuit2 the quotient gives the distance in feet from the fuse block to the center of distribution4 ,in such cases1 as shown in fig4 #hba1 the electrical center can be determined by adding together the lamp feet of the several sections ,a1 ,b1 ,c1 etc41 of the main and dividing the result by the #af c4p4 units4 ,thus the lamp feet of ,section ,a #aj lamps #aj feet #ajj ,b #i #e #de ,c #g #f #db ,d #f #d #bd ,e #e #e #be ,f #d #aj #dj ,g #b #e #aj ----- which added together gives a total of #bhf lamp feet4 ,this when divided by the ten #af c4p4 units comprising four #af c4p4 lamps and three #cb c4p4 lamps1 gives a little over #bh feet as the distance from the fuse block to the center of distribution1 the position of which is shown by the line ,m ,n in fig4 #hba1 while that of the geometrical center is shown by the line ,k ,l4 ,when the center of distribution is at a considerable distance from the supply circuit1 and it becomes advisable to divide the wiring into two distinct elements--a feeder and one or more mains1 the junction of the feeder and the mains should be located at the electrical center of the mains whenever possible4 ,when this is done1 it is obvious that the wire size of only one half the main needs to be calculated1 as both halves of the main are identical4 ,illustration3 ,,fig4 #hbb4--;,brown and ,sharpe 7,b4 ,s471 or ,american ,standard wire gauge4 ,this gauge was adopted by the brass manufacturers ,jan41 #aheh4 ,the cut is full size1 and therefore1 shows the actual sizes corresponding to the gauge numbers4 ,wire ,gauges4--,for the purpose of facilitating the measurement of wire1 a number of gauges have been designed by various wire manufacturing concerns4 ,the principal gauges used in the ,united ,states are the ,american or ,brown ,sharp's gauge2 the ,english standard or ,birmingham gauge2 ,washburn ,moen's standard gauge2 ,imperial wire gauge2 ,stubs' steel wire gauge1 and the ,u4 ,s4 ,standard wire gauge4 ,the several gauges are here given with explanation of their use4 ,the ,american ,standard or ,brown and ,sharp's ,gauge4--,this gauge is commonly designated as ,a4 ,w4 ,g4 or ,b4 ,s41 and has been adopted by brass manufacturers and is used mostly in measuring brass1 copper1 silver1 ,german silver1 and gold in both wire and plate4 ,birmingham or ,stub's ,wire ,gauge 7,b4 ,w4 ,g474--,old ,english ,standard and ,iron ,wire ,gauge4 ,birmingham or ,stubs' ,iron ,wire ,gauge is not the same as ,stubs' ,steel ,wire ,gauge4 ,a table of ,stub's ,steel ,wire ,gauge is given on page #gda4 ,illustration3 ,,fig4 #hbc4--,micrometer screw gauge4 ,it consists essentially of a screw whose thread is accurately turned to a pitch of some convenient fraction of an inch or centimetre4 ,when the screw is screwed home1 the surfaces of ,a and ,b meet1 and the instrument should then read zero on both the straight and the circular scale4 ,if this be not so1 there is a zero error which must be either allowed for1 or corrected by means of the screw provided for that purpose4 ,if the former course be adopted1 the reading of the instrument is taken when the faces ,a and ,b are in contact1 and this number added to or subtracted from the final reading according to whether the error makes the wire apparently smaller or greater than its real size4 ,the surfaces ,a and ,b are now screwed apart and then1 after the wire to be measured 7which should be clean and straight7 has been introduced between them1 they are screwed together to lightly grip the wire4 ,if the gauge be screwed up too tightly the value of the measurement is destroyed1 since a copper wire can easily be crushed1 and in addition the accurate screw may be permanently damaged4 ,to avoid the possibility of this happening1 screw gauges are provided with a ratchet which prevents an excessive force being applied to the screw4 ,if the pitch of the screw in the gauge be #jth of an inch1 and the circular scale consist of #ej divisions1 then for each revolution of the screw1 the surface ,b will travel a distance equal to the pitch1 that is #jth of an inch4 ,the graduations on an instrument of this kind are generally th of an inch on the straight scale1 with shorter lines to mark the half divisions4 ,the thickness of a wire on the straight scale can therefore be read to the nearest #jth inch4 ,each division of the circular scale represents #a_/ejth of a revolution of the screw1 which corresponds to a change in distance between ,a and ,b1 of #a_/ej of #a_/bj #a_/a1jjj in4 ,if then the reading on the straight scale be #a and on the circular scale #ce1 the distance between ,a and ,b is 4#a 4#jce 4#ace inch4 ,washburn and ,moen's ,standard ,wire ,gauge4--,commonly designated as ,w4 ,m4 ,g4 has been adopted by the ,u4 ,s4 ,steel ,corporation in making their wire4 ,new ,british ,standard 7,n4 ,b4 ,s474--,british ,imperial ,english ,legal ,standard and ,standard ,wire ,gauge1 and is variously abbreviated by ,s4 ,w4 ,g4 and ,i4 ,w4 ,g4 ,roebling ,gauge4--,washburn ,moen1 ,american ,steel ,wire ,co4's ,iron ,wire ,gauge4 ,illustration3 ,,figs4 #hbd and #hbe4--,u4 ,s4 wireman's calculating gauge2 views showing both sides4 ,on the side shown in fig4 #hbd1 set the required number of feet on the small circle opposite the required number of amperes on the large circle1 then set the small pointer at the required voltage and loss4 ,then on the other side 7fig4 #hbe7 the large pointer will indicate the required size of wire in ,b4 ,s4 gauge1 and will also indicate the safe carrying capacity1 while the wire may be gauged by slot ,a 7fig4 #hbd74 ,u4 ,s4 ,standard ,wire ,gauge4--,this gauge is used for measuring sheet and plate iron1 and steel1 by the ,u4 ,s4 ,government in assessing duties1 and in making requisitions for supplies4 ,old ,english ,standard ,wire ,gauge4--,the old ,english gauge is the same as the ,birmingham or ,stubs' standard gauge1 commonly designated as ,b4 ,w4 ,g4 ,it is used chiefly for measuring sheet iron and steel1 also soft steel and iron wire4 ,london ,gauge4--,old ,english 7not ,old ,english ,standard74 ,from the foregoing it is seen that great confusion exists with such a multiplicity of gauges and emphasizes the importance of specifying the gauge and of knowing what gauge to use4 ,in using the gauges known as ,stubs' ,gauges1 there should be constantly borne in mind the difference between the ,stubs' ,iron ,wire ,gauge and the ,stubs' ,steel ,wire ,gauge4 ,the ,stubs' ,iron ,wire ,gauge is the one commonly known as the ,english ,standard ,wire1 or ,birmingham ,gauge and designates the ,stubs' soft wire sizes4 ,the ,stubs' ,steel ,wire ,gauge is the one that is used in measuring drawn steel wire or drill rods of ,stubs' make and is also used by many makers of ,american drill rods4 ,,stubs' ,,steel ,,wire ,,gauge ---------------------------------------- ---------------------------------------- ----------------------------------- ,size of ,size of ,size of ,size of ,letter4 ,letter ,no4 of ,number ,no4 of ,number ,no4 of ,number in ,wire in ,wire in ,wire in ,decimals4,gauge4,decimals4,gauge4,decim als4,gauge4,decimals4 ---------------------------------------- ---------------------------------------- ----------------------------------- ,z 4#dac #a 4#bbg #bh 4#aci #ee 4#jej ,y 4#djd #b 4#bai #bi 4#acd #ef 4#jde ,x 4#cig #c 4#bab #cj 4#abg #eg 4#jdb ,w 4#chf #d 4#bjg #ca 4#abj #eh 4#jda ,v 4#cgg #e 4#bjd #cb 4#aae #ei 4#jdj ,u 4#cfh #f 4#bja #cc 4#aab #fj 4#jci ,t 4#ceh #g 4#aii #cd 4#aaj #fa 4#jch ,s 4#cdh #h 4#aig #ce 4#ajh #fb 4#jcg ,r 4#cci #i 4#aid #cf 4#ajf #fc 4#jcf ,q 4#ccb #aj 4#aia #cg 4#ajc #fd 4#jce ,p 4#cbc #aa 4#ahh #ch 4#aja #fe 4#jcc ,o 4#caf #ab 4#ahe #ci 4#jii #ff 4#jcb ,n 4#cjb #ac 4#ahb #dj 4#jig #fg 4#jca ,m 4#bie #ad 4#ahj #da 4#jie #fh 4#jcj ,l 4#bij #ae 4#agh #db 4#jib #fi 4#jbi ,k 4#bha #af 4#age #dc 4#jhh #gj 4#jbg ,j 4#bgg #ag 4#agb #dd 4#jhe #ga 4#jbf ,i 4#bgb #ah 4#afh #de 4#jha #gb 4#jbd ,h 4#bff #ai 4#afd #df 4#jgi #gc 4#jbc ,g 4#bfa #bj 4#afa #dg 4#jgg #gd 4#jbb ,f 4#beg #ba 4#aeg #dh 4#jge #ge 4#jbj ,e 4#bej #bb 4#aee #di 4#jgb #gf 4#jah ,d 4#bdf #bc 4#aec #ej 4#jfi #gg 4#jaf ,c 4#bdb #bd 4#aea #ea 4#jff #gh 4#jae ,b 4#bch #be 4#adh #eb 4#jfc #gi 4#jad ,a 4#bcd #bf 4#adf #ec 4#jeh #hj 4#jac #bg 4#adc #ed 4#jee ---------------------------------------- ---------------------------------------- ----------------------------------- ,the following table gives the diameters1 in decimal parts of an inch1 of the various sizes of wire corresponding to the number of gauge numbers of the different standard wire gauges used in the ,united ,states4 ,,table ,,of ,,various ,,wire ,,gauges ,in decimal parts of an inch ---------------------------------------- ---------------------------------------- ---------------------------------------- -- ,number ,ameri- ,birming- ,wash- ,tren- ,g4,w4 ,old ,brit- of can1 or ham1 or burn ton ,pren- ,eng- ish ,wire ,brown ,stubs ,moen ,iron tiss1 lish1 ,stan- ,gauge ,sharpe 7,b4,w4,g47 ,mfg4 ,co41 ,co41 ,holy- ,from dard 7,b4,s47 ,worces- ,tren- oke1 ,brass 7,s4,w4- ter1 ton1 ,mass4 ,mfrs' ,g47 ,mass4 ,n4,j4 ,list ---------------------------------------- ---------------------------------------- ---------------------------------------- -- #jjjjjjj 4#ejj #jjjjjj 4#dfj 4#dfd #jjjjj 4#dcj 4#dej 4#dcb #jjjj 4#dfjjj 4#ded 4#cic 4#djj 4#djj #jjj 4#djifd 4#dbe 4#cfb 4#cfj 4#cehf 4#cgb #jj 4#cfdhj 4#chj 4#cca 4#ccj 4#cbhb 4#cdh #j 4#cbdhf 4#cdj 4#cjg 4#cje 4#biid 4#cbd #a 4#bhicj 4#cjj 4#bhc 4#bhe 4#bggg 4#cjj #b 4#begfc 4#bhd 4#bfc 4#bfe 4#beia 4#bgf #c 4#bbidb 4#bei 4#bdd 4#bde 4#bdja 4#beb #d 4#bjdca 4#bch 4#bbe 4#bbe 4#bbcj 4#bcb #e 4#ahaid 4#bbj 4#bjg 4#bje 4#bjdg 4#bab #f 4#afbjb 4#bjc 4#aib 4#aij 4#ahhe 4#aib #g 4#addbh 4#ahj 4#agg 4#age 4#ageh 4#agf #h 4#abhdi 4#afe 4#afb 4#afj 4#afje 4#afj #i 4#aaddc 4#adh 4#adh 4#ade 4#adga 4#add #aj 4#ajahi 4#acd 4#ace 4#acj 4#acea 4#abh #aa 4#jijgdb 4#abj 4#abj 4#aage 4#abje 4#aaf #ab 4#jhjhjh 4#aji 4#aje 4#ajej 4#ajfe 4#ajd #ac 4#jgaifa 4#jie 4#jibj 4#jibe 4#jibh 4#jibj #ad 4#jfdjhd 4#jhc 4#jhjj 4#jhjj 4#jhaf 4#jhcjj 4#jhjj #ae 4#jegjfh 4#jgb 4#jgbj 4#jgjj 4#jgbf 4#jgbjj 4#jgbj #af 4#jejhbj 4#jfe 4#jfcj 4#jfaj 4#jfbg 4#jfejj 4#jfdj #ag 4#jdebeg 4#jeh 4#jedj 4#jebe 4#jedf 4#jehjj 4#jefj #ah 4#jdjcjc 4#jdi 4#jdgj 4#jdej 4#jdgh 4#jdijj 4#jdhj #ai 4#jcehij 4#jdb 4#jdaj 4#jdjj 4#jdaa 4#jdjjj 4#jdjj #bj 4#jcaifa 4#jce 4#jcej 4#jcej 4#jcea 4#jcejj 4#jcfj #ba 4#jbhdfb 4#jcb 4#jcbj 4#jcaj 4#jcba 4#jcaej 4#jcbj #bb 4#jbecdg 4#jbh 4#jbhj 4#jbhj 4#jbij 4#jbiej 4#jbhj #bc 4#jbbega 4#jbe 4#jbej 4#jbej 4#jbfa 4#jbgjj 4#jbdj #bd 4#jbjajj 4#jbb 4#jbcj 4#jbbe 4#jbca 4#jbejj 4#jbbj #be 4#jagijj 4#jbj 4#jbjj 4#jbjj 4#jbab 4#jbcjj 4#jbjj #bf 4#jaeidj 4#jah 4#jahj 4#jahj 4#jaid 4#jbjej 4#jahj #bg 4#jadaie 4#jaf 4#jagj 4#jagj 4#jahb 4#jahge 4#jafd #bh 4#jabfda 4#jad 4#jafj 4#jafj 4#jagj 4#jafej 4#jadh #bi 4#jaabeg 4#jac 4#jaej 4#jaej 4#jafc 4#jaeej 4#jacf #cj 4#jajjbe 4#jab 4#jadj 4#jadj 4#jaef 4#jacge 4#jabd #ca 4#jjhibh 4#jaj 4#jacj 4#jacj 4#jadf 4#jabbe 4#jaaf #cb 4#jjgiej 4#jji 4#jabj 4#jabj 4#jacf 4#jaabe 4#jajh #cc 4#jjgjhj 4#jjh 4#jaaj 4#jaaj 4#jacj 4#jajbe 4#jajj #cd 4#jjfcje 4#jjg 4#jajj 4#jajj 4#jaah 4#jjiej 4#jjib #ce 4#jjefae 4#jje 4#jjie 4#jjie 4#jaji 4#jjijj 4#jjhd #cf 4#jjejjj 4#jjd 4#jjij 4#jjij 4#jajj 4#jjgej 4#jjgf #cg 4#jjddec 4#jjhe 4#jjhe 4#jjie 4#jjfej 4#jjfh #ch 4#jjcife 4#jjhj 4#jjhj 4#jjij 4#jjege 4#jjff #ci 4#jjceca 4#jjge 4#jjge 4#jjhc 4#jjejj 4#jjeb #dj 4#jjcade 4#jjgj 4#jjgj 4#jjgh 4#jjdej 4#jjdh #da 4#jjdd #db 4#jjdj ---------------------------------------- ---------------------------------------- ---------------------------------------- -- ,,note4--,the sizes of wire are ordinarily expressed by an arbitrary series of numbers4 ,unfortunately there are several independent numbering methods1 so that it is always necessary to specify the method or wire gauge used4 ,the above table gives the numbers and diameters in decimal parts of an inch for the various wire gauges in general use4 ,wiring ,terms4--,the various members of a complex wiring installation are designated feeders1 sub-feeders1 mains1 branches1 and taps4 ,a feeder is a stretch of wiring to which no connection is made except at its two ends4 ,a sub-feeder is of the same class as a feeder1 but is distinguished either by being one of two or more connecting links between the end of a single feeder and several distributing mains1 or by constituting an extension of a feeder4 ,illustration3 ,,fig4 #hbf4 ,circuit diagram illustrating names of the various parts4 ,a circuit may consist of the following parts as defined in the accompanying text3 #a1 feeder1 #b1 sub-feeders1 #c1 mains1 #d1 branches1 #e1 taps4 ,it is well to clearly distinguish between these divisions because the terms are constantly used in wiring4 ,a main is a stretch of wiring supplied from one or more feeders or sub-feeders and distributing current to a number of taps1 or else to a number of branches4 ,a branch distributes current among a number of lamps1 etc4 ,a tap almost invariably delivers current to a single lamp or other device4 ,reference to fig4 #hbf will make these definitions clearer4 ,this diagram is intended merely to illustrate the above definitions and does not represent any special plan of wiring4 ,illustration3 ,,figs4 #hbg and #hbh4 ,simplest forms of circuit1 consisting of a main with one or more lamps at the end4 ,the smallest size wire allowed 7,no4 #ad ,b4,s4 gauge7 will generally be found amply large for such circuits4 ,note carefully the difference between a main and a branch by comparison with fig4 #hbf4 ,a main begins from a fuse block1 while a branch is an offset from a main without any fuse block4 ,the simplest possible wiring installation is one in which a single lamp or compact cluster of lamps is located at the end of a main1 as shown in figs4 #hbg and #hbh4 ,in such cases calculations are almost always unnecessary1 for the reason that ,no4 #ad wire1 the smallest size allowed by the underwriters1 will supply several lamps at a long distance 7as interior wiring goes7 with a very moderate drop4 ,for example1 if the three lamps shown at the end of the main in fig4 #hbh1 be of #af candle power each1 and the voltage of the supply circuit be #aaj volts1 a main of ,no4 #ad wire would supply the lamps at a distance of #ace feet from the fuse block with a drop of only #a per cent4 ,when the lamps are strung along the main1 however1 as in fig4 #hbf1 it is sometimes necessary to choose the size of wire with regard to the drop1 and in order to do this the main must be measured for either ampere feet or lamp feet4 ,wire ,calculations4--,the problem of calculating the size of wire will be presented here in as simple a form as possible1 with explanation of the various steps so that any one can understand how the formula is derived4 ,in determining the size of wire1 there are four known factors which enter into the calculation1 viz43 #a4 ,length of circuit in feet2 #b4 ,maximum current in amperes2 #c4 ,drop or volts lost in the circuit1 in of the impressed voltage2 #d4 ,heating effect of the current4 ,the calculation is based on the mil foot1 which as previously explained1 is a foot of copper wire one mil in diameter and whose resistance is equal to #aj4gi ohms at #ge ,fahr4 ,illustration3 ,,fig4 #hbi4--,wiring for lights requiring unusually long feeders4 ,the first step is to find an expression for the resistance of the wire which may be later substituted in ,ohm's law formula4 ,accordingly1 the resistance of any conductor is equal to its length in feet multiplied by its resistance per mil foot and the product divided by its area in circular mils1 thus3 length in feet resistance per mil foot resistance in ohms ---------------------------------------- ---------------------------------------- -- circular mils feet #aj4h or ohms ------------------------- 7#a7 circular mils 7calling the resistance per mil foot #aj4h instead of #aj4gi to facilitate calculation74 ,,lamp ,,table ,,for ,,rubber ,,covered ,,wires ,showing the maximum number of #af candle power #aaj to #bdj volt lamps in parallel that may be carried by the various sizes of wire without violating the underwriters' rules4 ---------------------------------------- ---------------------------------------- --------------------------------------- ,wire size ,amperes#c4a-watt lamps#c4e-watt lamps4 #d-watt lamps4 ,b4 ,s4 ---------------------------------------- ---------------------------------------- ----- gauge ,at #aaj #bbj ,at #aaj #bbj #bbj #bcj #bdj volts ,v4 volts ,v4 ,v4 ,v4 ,v4 ---------------------------------------- ---------------------------------------- ---------------------------------------- #jjjj #baj #dfb #ibd #dab #hbe #gbb #ged #ghg #jjj #agg #chi #ggh #cdg #fie #fjh #fcf #ffc #jj #aej #ccj #ffj #bid #ehi #eae #eci #efb #j #abg #bgi #eeh #bdi #dii #dcf #def #dgf #a #ajg #bce #dgj #baj #dbj #cfg #chd #dja #b #ij #aig #cif #agf #cec #cji #cbc #ccg #c #gf #afg #ccd #adi #bih #bfa #bgc #bhe #d #fe #adc #bhf #abg #bee #bbc #bcc #bdc #e #ed #aah #bcg #ajf #bab #ahe #aid #bjb #f #df #aja #bjb #ij #ahj #aeh #afe #agb #h #cc #gb #ade #fd #abi #aac #aah #abc #aj #bd #eb #aje #dg #id #hb #hf #ij #ab #ag #cg #gd #cc #ff #eh #fa #fc #ad #ab #bf #eb #bc #dg #da #dc #de #afc #f #ac 44 #aa 44 #bj #ba #bb ---------------------------------------- ---------------------------------------- ---------------------------------------- #c ,this size can be used only in the shape of flexible cord4 ,now1 according to ,ohm's law1 volts amperes ohms 7#b7 hence1 substituting in 7#b7 the value for the resistance in ohms1 as obtained in 7#a73 feet #aj4h volts amperes ------------------------- circular mils or using the usual symbols feet #aj4h ,e ,i ------------------------- 7#c7 circular mils or expressed in words1 formula 7#c7 means that the volts lost or drop between the beginning and end of a circuit is equal to the current flowing through the circuit multiplied by the product of the conductors' length in feet multiplied by the resistance of one mil foot of wire1 divided by the area of the conductor in circular mils4 ,,lamp ,,table ,,for ,,weather ,,proof ,,wires ,showing the maximum number of #af candle power #abj to #bdj volt lamps in parallel that may be carried by various sizes of weather proof wire without violating the underwriters' rules4 ---------------------------------------- ---------------------------------------- ---------------------------------------- - ,wire ,amperes #c4a-watt lamps4#ce-watt lamps4 #d-watt lamps4 size ---------------------------------------- ---------------------------------------- ---------- ,b4 ,s4 #aaj #bbj #aaj #bbj #bbj #bcj #bdj gauge ,v4 ,v4 ,v4 ,v4 ,v4 ,v4 ,v4 ---------------------------------------- ---------------------------------------- ------------------------------------- #jjjj #cab #fhf #acgb #fab #abbe #ajgb #aaba #aagj #jjj #bfb #egf #aaeb #ead #ajbi #ijj #ida #ihb #jj #bbj #dhd #ifh #dcb #hfd #gef #gij #hbe #j #ahe #djg #had #cfc #gbf #fcf #ffe #fic #a #aef #cdc #fhf #cjf #fab #ecf #efj #ehe #b #aca #bhh #egf #beg #ead #dej #dgj #dia #c #aaj #bdb #dhd #baf #dcb #cgh #cie #dab #d #ib #bjb #djd #ahj #cfa #caf #ccj #cde #e #gg #afi #cch #aea #cjb #bfd #bgf #bhh #f #fe #adc #bhf #abg #bee #bbc #bcc #bdc #h #df #aja #bjb #ij #ahj #aeh #afe #agb #aj #cb #gj #adj #fb #abe #aaj #aae #abj #ab #bc #ej #aja #de #ij #gi #hb #hf #ad #af #ce #gj #ca #fb #ee #eg #fj ---------------------------------------- ---------------------------------------- ------------------------------------- ,now1 since the length of the circuit is given as the run or distance one way1 that is1 one half the total length of wire in the circuit1 formula 7#c7 must be multiplied by #b to get the total drop1 that is3 feet #aj4h ,x #b ,i feet #ba4f ,e ,i ----------------------------- ------------------------------- 7#d7 circular mils circular mills ,solving the last equation for the unknown quantity1 the following equation is obtained for size of wire3 ,illustration3 ,,figs4 #hcj and #hca4--,symmetrical and unsymmetrical distribution4 ,when a main is supplied by a feeder1 the junction of the two1 if practicable1 is located at the electrical center of the main1 as indicated in fig4 #hcj1 so that the distribution is symmetrical1 that is1 the ampere feet each way from the junction are the same4 ,this is nearly always practicable in surface wiring1 and when it is practiced it is only necessary to calculate the wire size for one-half of the main1 as the other half is identical4 ,in fig4 #hcj there are four lamps on each side of the junction1 ,j2 the center of each group is at a distance1 ,m1 so that the lamp feet in each half of the main are #e ,m4 ,the lamp feet of the feeder would be #aj ,n1 ,n being the distance from the feeder fuse block to the junction1 ,j4 ,in concealed work1 however1 it does not always happen that a feeder can be made to join a main at its electrical center2 when this is not practicable1 each end of the main should be figured separately4 ,in fig4 #hca1 for instance1 the main has five lamps on one side and two on the other1 and the distances from the junction to the centers of the two groups are at unequal distances ,s and ,s'4 ,if the distance ,s be #ad feet1 and the lamps1 #af c4 p41 the lamp feet in the left hand main equals #e #ad #gj1 while in the main to the right1 taking ,s' at #aj feet1 there are only #b #aj #bj lamp feet4 ,hence what appears to be one continuous main in this case would have to be treated as two mains1 and each part figured separately4 ,i feet #ba4f amperes feet #ba4f circular mils ------------------------------- ---------------------------------------- -- 7#e7 ,e drop ,the following practical example is given to illustrate the application of the formula just obtained3 ,,example4--,what size wire should be used on a #bej volt circuit to transmit a current of #bjj amperes a distance of #cej feet to a center of distribution with a loss of three per cent4 under full load8 ,the volts lost or drop is equal to #bej 4#jc #g4e volts4 ,,properties ,,of ,,copper ,,wire ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------------------------- ,number ,diameter ,area in ,weight in pounds ,resistance at #fh ,fahr4 of gauge in circular ---------------------------------------- ---------------------------------------- ---------------------------- ,b4 ,s4 mils mils #a1jjj feet mile feet per #a1jjj feet mile pound ---------------------------------------- ---------------------------------------- ---------------------------------------- ----------------------------------- #jjjj #dfj #baa1fjj #fdj4e #c1cha #a4efa 4#jdhic 4#behc #jjj #dji4f #afg1hjj #ejh #b1fhb #a4ifi 4#jfagj 4#cbeh #jj #cfd4h #acc1ajj #djb4h #b1abg #b4dhb 4#jgghj 4#dajh #j #cbd4i #aje1ejj #cai4e #a1fhg #c4acj 4#jihaa 4#eahj #a #bhi4c #hc1fij #bec4c #a1ccg #c4idg 4#abcgj 4#feca #b #beg4f #ff1cgj #bjj4i #a1jfb #d4igg 4#aefj 4#hbcg #c #bbi4d #eb1fcj #aei4c #hda4a #f4bgf 4#aifg #a4jchf #d #bjd4c #da1gdj #abf4d #ffg4d #g4iad 4#bdhj #a4cjid #e #aha4i #cc1ajj #ajj4b #ebi4j #i4ihj 4#cabh #a4feaf #f #afb4j #bf1bej #gi4df #dai4e #ab4ehj 4#cidd #b4jhbd #g #add4c #bj1hbj #fc4jb #ccb4g #ae4hg 4#digc #b4fbeg #h #abh4e #af1eaj #di4ih #bfc4i #bj4ja 4#fbga #c4caaa #i #aad4d #ac1jij #ci4fc #bji4b #be4bc 4#gijh #d4aged #aj #aja4i #aj1chj #ca4ac #aff4j #ca4hb 4#iigb #e4bfeb #aa #ij4gd #h1bcd #bd4ic #aca4f #dj4ab #a4beg #f4fcgj #ab #hj4ha #f1ecj #ai4gg #ajd4d #ej4ei #a4ehf #h4cgd #ac #ga4if #e1agh #ae4fh #hb4gi #fc4gi #b4jjj #aj4efj #ad #fd4jh #d1ajg #ab4dc #fe4fc #hj4dd #b4eba #ac4caa #ae #eg4jg #c1beg #i4heh #eb4jeaja4d #c4agi #af4ghe #af #ej4hb #b1ehc #g4hah #da4bhabg4i #d4jji #ba4afh #ag #de4bf #b1jdh #f4bjj #cb4gdafa4c #e4jee #bf4fij #ah #dj4cj #a1fbd #d4iag #be4ifbjc4d #f4cgd #cc4fee #ai #ce4hi #a1bhh #c4hii #bj4eibef4e #h4jch #db4ddj #bj #ca4if #a1jbb #c4jib #af4cccbc4d #aj4ad #ec4edj ---------------------------------------- ---------------------------------------- ---------------------------------------- ----------------------------------- ,substituting the given value in formula 7#e7 #cej #bjj #ba4f circular mils ------------------------------------ #bja1fjj4 #g4e ,diameter #b #bja1fjj #ddi circular mils or 4#ddi in4 ,from the table 7on page #gca or on page #gdb7 the nearest 7larger7 size of wire is #jjjj ,b4 ,s4 gauge4#d #d ,,caution4--,the size thus obtained should be compared with the table of carrying capacity of wires as given on page #gca to see if the wires would have to carry more than the allowable current4 ,,wiring ,,table ,,for ,,light ,,and ,,power ,,circuits ,,volts ,,percentage ,,of ,,loss #bjjj #a4g #a4e #a4d #a4b #a4a #a4j #j4ge #j4e #ajjj #c4d #b4i #b4g #b4d #b4b #b4j #a4e #a4j #ejj #f4e #e4g #f4b #d4h #d4c #c4i #b4i #b4j #bbj #ac4g #ab4j #aa4j #aj4c #i4c #h4c #f4e #d4d #aaj -- -- #bj4j #ah4e #ag4j #ae4d #ab4j #h4d #eb -- -- -- -- -- -- #bb4d #af4a ,,actual ,,volts ,,lost ,carrying ,capacity ,size #ce #cj #bg4e #be #bb4e #bj #ae #aj ,amperes4 ,b4 ,s4 #cjj #jjjj #cdehjj #bifdjj #bgagjj #bdgjjj #bbbcjj #aigfjj #adhbjj #ihhjj #bde #jjj #bgddjj #bcebjj #baefjj #aifjjj #agfdjj #aefhjj #aagfjj #ghdjj #bae #jj #bagebe #ahfdej #agjiab #aeecge #acihcg #abdcjj #icbbe #fbaej #aij #j #agbeej #adgijj #aceege #abcbej #aajibe #ihfjj #gciej #dicjj #afj #a #acfhej #aagcjj #ajgebe #iggej #hgige #ghbjj #ehfej #ciajj #ace #b #ajhejj #icjjj #hebej #ggejj #figej #fbjjj #dfejj #cajjj #aae #c #hfajj #gchjj #fgfej #faejj #eecej #dibjj #cfijj #bdfjj #ajj #d #fhbej #ehejj #ecfbe #dhgej #dchge #cijjj #bibej #aiejj #ij #e #edbej #dfejj #dbfbe #chgej #cdhge #cajjj #bcbej #aeejj #hj #f #dcjej #cfijj #cchbe #cjgej #bgfge #bdfjj #ahdej #abcjj #fj #h #bfife #bcacj #babjb #aibge #agcdg #aedbj #aaefe #ggaj #dj #aj #afige #adeej #acccg #ababe #ajiab #igjj #gbge #dhej #cj #ab #ajfge #iaej #hchh #gfbe #fhfb #fajj #dege #cjej #bb #ad #fgbj #egfj #ebhj #dhjj #dcbj #chdj #bhhj #aibj #ee #af #dbce #cfcj #ccbh #cjbe #bgbc #bdbj #ahae #abaj ---------------------------------------- ---------------------------------------- ---------------------------------------- ----------------------- ,,volts ,,percentage ,,of ,,loss #bjjj #j4de #j4d #j4ce #j4c #j4be #j4b #j4ae #j4a #j4je #ajjj #j4i #j4h #j4g #j4f #j4e #j4d #j4c #j4b #j4a #ejj #a4h #a4f #a4d #a4b #a4j #j4h #j4f #j4d #j4b #bbj #c4i #c4e #c4a #b4g #b4b #a4h #a4d #j4i #j4de #aaj #g4f #f4h #f4j #e4b #d4d #c4e #b4g #a4h #j4i #eb #ad4g #ac4c #aa4h #aj4c #h4h #g4a #e4e #c4g #a4i ,,actual ,,volts ,,lost ,carrying ,capacity ,size #i #h #g #f #e #d #c #b #a ,amperes4 ,b4 ,s4 #cjj #jjjj #hhibj #gijdj #fiafj #eibhj #didjj #ciebj #bifdj #aigfj #ihhj #bde #jjj #gjefj #fbgbj #edhhj #dgjdj #cibjj #cacfj #bcebj #aefhj #ghdj #bae #jj #eeice #digbj #dceje #cgbij #cajge #bdhfj #ahfde #abdcj #fbae #aij #j #ddcgj #ciddj #cdeaj #biehj #bdfej #aigbj #adgij #ihfj #dicj #afj #a #ceaij #cabhj #bgcgj #bcdfj #aieej #aefdj #aagcj #ghbj #ciaj #ace #b #bgijj #bdhjj #bagjj #ahfjj #aeejj #abdjj #icjj #fbjj #cajj #aae #c #bbadj #aifhj #agbbj #adgfj #abcjj #ihdj #gchj #dibj #bdfj #ajj #d #ageej #aefjj #acfej #aagjj #igej #ghjj #ehej #cijj #aiej #ij #e #aciej #abdjj #ajhej #icjj #ggej #fbjj #dfej #cajj #aeej #hj #f #aajgj #ihdj #hfaj #gchj #faej #dibj #cfij #bdfj #abcj #fj #h #fici #fafh #ecig #dfbf #chee #cjhd #bcac #aedb #gga #dj #aj #dcfe #chhj #ccie #biaj #bdbe #aidj #adee #igj #dhf #cj #ab #bgde #bddj #bace #ahcj #aebe #abbj #iae #faj #cje #bb #ad #agbh #aecf #acdd #aaeb #ifj #gfh #egf #chd #aib #ee #af #ajhi #ifh #hdg #gbf #fje #dhd #cfc #bdb #aba ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------- #e ,,note4--,in case a larger loss than any given in the table is required1 proceed as follows3--,divide the ampere feet by #aj and then refer to column of ,actual ,volts ,lost divided by #aj1 from which the size of wire is found as before4 ,,rule4--,multiply current in amperes by single distance and refer to the nearest corresponding number under column of actual volts lost1 to find size of wire4 ,it should also be noted that the underwriters prohibit the use of wire smaller than ,no4 #ad ,b4 ,s4 gauge1 except as allowed for fixture work and pendant cord4 ,,table ,,of ,,wire ,,equivalents ,,gauge ,,number ,,of ,,wires ,b4 ,s4 #b #d #h #af #cb #fd #abh #bef #eab #ajbd #bjdh #djif #haib #afchd #jjjj #j #c #f #i #ab #ae #ah #ba #bd #bg #cj #cc #cf #ci #jjj #a #d #g #aj #ac #af #ai #bb #be #bh #ca #cd #cg #dj #jj #b #e #h #aa #ad #ag #bj #bc #bf #bi #cb #ce #ch #jf #j #c #f #i #ab #ae #ah #ba #bd #bg #cj #cc #cf #ci #ag #a #d #g #aj #ac #af #ai #bb #be #bh #ca #cd #cg #dj #bh #b #e #h #aa #ad #ag #bj #bc #bf #bi #cb #ce #chci #df #c #f #i #ab #ae #ah #ba #bd #bg #cj #cc #cf #cidaj #eg #d #g #aj #ac #af #ai #bb #be #bh #ca #cd #cg #djeaa #fh #e #h #aa #ad #ag #bj #bc #bf #bi #cb #ce #chfab #gi #f #i #ab #ae #ah #ba #bd #bg #cj #cc #cf #cigac #haj #g #aj #ac #af #ai #bb #be #bh #ca #cd #cg #djhad #iaa #h #aa #ad #ag #bj #bc #bf #bi #cb #ce #chiae #ajab #i #ab #ae #ah #ba #bd #bg #cj #cc #cf #ciajaf #aaac #aj #ac #af #ai #bb #be #bh #ca #cd #cg #djaaag #abad #aa #ad #ag #bj #bc #bf #bi #cb #ce #chabah #acae #ab #ae #ah #ba #bd #bg #cj #cc #cf #ciacai #adaf #ac #af #ai #bb #be #bh #ca #cd #cg #djadbj #aeag #ad #ag #bj #bc #bf #bi #cb #ce #chaeba #afah #ae #ah #ba #bd #bg #cj #cc #cf #ciafbb #agai #af #ai #bb #be #bh #ca #cd #cg #djagbc #ahbj #ag #bj #bc #bf #bi #cb #ce #chahbd #aiba #ah #ba #bd #bg #cj #cc #cf #ciaibe #bjbb #ai #bb #be #bh #ca #cd #cg #djbjbf #babc #bj #bc #bf #bi #cb #ce #chbabg #bbbd #ba #bd #bg #cj #cc #cf #cibbbh #bcbe #bb #be #bh #ca #cd #cg #djbcbi #bdbf #bc #bf #bi #cb #ce #chbdcj #bebg #bd #bg #cj #cc #cf #cibeca #bfbh #be #bh #ca #cd #cg #djbfcb #bgbi #bf #bi #cb #ce #chbgcc #bhcj #bg #cj #cc #cf #cibhcd #bica #bh #ca #cd #cg #djbice #cjcb #bi #cb #ce #chcjcf #cacc #cj #cc #cf #cicacg #cbcd #ca #cd #cg #djcbch #ccce #cb #ce #chccci #cdcf #cc #cf #cicddj #cecg #cd #cg #djcfci #ce #chcgci #cf #cichdj #cg #dj ,ques4 ,if the calculated size of wire be larger than any in the table how is the required area obtained8 ,ans4 ,by using two or more smaller wires in parallel1 whose combined area is equal to the required area4 ,to facilitate finding the equivalent sizes the above table of wire equivalents has been prepared4 ,ques4 ,how is the table of wire equivalents used8 ,ans4 ,to use the table1 find in the vertical column at left the size of conductor desired2 then follow along horizontally until the size of wire that is desired to use for the strands1 and the corresponding number at top of column will give the number of strands of that size wire required4 ,illustration3 ,,fig4 #hcb4--;,break down switch for use on three wire circuit1 enabling it to be operated break down fashion with the two outers connected together and the neutral wire serving as one side of the resultant two wire circuit4 ,such circuits must be figured as two wire installations of one half the three wire voltage4 ,the size of the neutral wire of a three wire circuit depends on conditions of operation4 ,three wire circuits for occasional two wire working1 must have a neutral wire whose cross section is equal to the combined cross sections of the two outer wires4 ,this plan is useful for buildings supplied from a central station1 as it will be satisfactory for two wire operation in emergencies1 and for three wire1 two phase or three phase distribution should the central station ultimately be changed over to either of those alternating current systems4 ,the expense for the extra copper in the beginning will not be nearly so great as that entailed by a change in the wiring later on should developments require it4 ,it is permissible1 however1 to make the cross section of the neutral wire smaller than that of each outer wire1 if one be reasonably sure that there will never be any changes such as those just mentioned1 and if the drop in the two outer wires do not exceed #a per cent4 ,under such conditions1 it will be found a very good rule to calculate the neutral wire of a principal feeder for a maximum unbalancing of #be per cent1 that is1 a condition under which the current in one outer wire will be #ge per cent of the current in the other one1 the current in the neutral being #be per cent of that in the heavier loaded outer wire4 ,ques4 ,what is the significance of the zig-zag line8 ,ans4 ,the figures below this line give the gauge numbers of two wires which will have the same conductivity as the corresponding conductor in left hand column4 ,,table ,,of ,,cable ,,capacities ,illustration3 ,,fig4 #hcc4--;,diagram showing capacities of cables for both open and concealed work as allowed by the underwriters4 ,incandescent ,lamps on #ffj ,watt ,circuits4--,the standard incandescent lamp is rated as equivalent to the light given by #af candles1 and may consume1 according to type and make1 from #ej to #ef watts1 or from #c4a to #c4e watts per candle power4 ,therefore1 a #ffj watt circuit will carry thirteen #af candle power #di4f watt lamps1 or eleven #ef watt lamps4 ,illustration3 ,,fig4 #hcd4--;,diagram showing symmetrical and unsymmetrical distribution4 ,the two #e lamp centers are located at equal distances from the distributing pocket or cabinet1 ,p1 so that the sub-feeders1 ,a and ,a'1 have equal values of lamp feet4 ,the sub-feeders1 ,b1 ,b'1 have equal lengths1 but as one supplies #aj lamps1 and the other #af1 the lamp feet are different1 and each sub-feeder must therefore be figured separately4 ,the main1 ,g1 should be considered as a part of the sub-feeder1 ,b1 in order to avoid the necessity for a fuse at the junction of the two4 ,as it is symmetrically divided1 only one-half of it would be considered4 ,thus1 if the sub-feeder1 ,b1 were #ej feet long1 and the main1 ,g1 #cj feet long1 ,b would have #af #ej #hjj lamp feet and one-half of the main would have #h #ae #abj lamp feet 7assuming all #af c4 p4 lamps74 ,hence #hjj #abj #ibj lamp feet should be taken as the load length and the proper size wire used for that figure1 making the sub-feeder1 ,b1 of the same size as the main1 ,g4 ,the same procedure applies to the sub-feeder ,b' and main ,g'2 also to the sub-feeder1 ,e1 and the main1 ,f4 ,the proper sizes of wire for the different circuits is easily found from the lamp feet table1 after having calculated the lamp feet assigned the drop4 ,illustration3 ,,figs4 #hce and #hcf4--,the tree and modified tree systems of wiring4 ,the tree system consists of a feeder reducing in size and supplying mains for each floor1 the general arrangement resembling the trunk and branches of a tree4 ,since fuses must be inserted on each floor where the size of the feeder is reduced1 the system requires a large number of joints1 and in the event of a fuse blowing it could not be quickly located4 ,the tree system is not to be recommended1 as it results in considerable drop1 and at full load the lamps nearest the point of supply will either burn too brightly or those more remote will not give the rated candle power4 ,in the modified tree system1 fig4 #hcf1 the size of the feeder is not reduced4 ,with this arrangement the losses are considerably reduced owing to the much smaller losses on the feeder between those centers farthest away from the point of supply4 ,the proper size of wire for a #ffj watt circuit will depend upon the voltage for which the lamps are made4 ,for example3 a #af candle power lamp which consumes #ef watts on #aaj volt circuit will take1 #ef #aaj 4#e or ampere of current1 while the same lamp1 if made for #bbj volts1 will take only #ee #bbj 4#be or ampere4 ,therefore1 eleven #af candle power #ef watt lamps will require a current of #e amperes at #aaj volts1 or #b amperes at #bbj volts4 ,according to the laws of resistance1 the resistance of a round wire is inversely proportional to the square of the diameter1 and if the circuit be taken at #ajj feet1 and the allowable percentage of drop at #a volt1 then according to formula1 7#e7 on page #gdh1 the wire required for a circuit carrying eleven #af candle power #ef watt #aaj volt lamps1 will have a cross sectional area of1 #e4e #ajj #ba4f -------------------------------- #aa1hhj circular mils4 #a while the same number of lamps on a #bbj volt circuit will require wire having a cross sectional area of1 #b4ge #ajj #ba4f --------------------------------- #e1idj circular mils4 #a ,in order to conform to the underwriters' requirements1 ,no4 #h4 ,b4 ,s4 gauge1 wire must be used for the circuit carrying the #aaj volt lamps1 while ,no4 #ab1 ,b4 ,s4 wire1 would be sufficient for the #bbj volt circuit4 ,in the case shown in fig4 #hbi1 the branch circuits ,a and ,b are identical1 each supplying four #af candle power lamps requiring #c4e watts per candle power at #aaj volts or carrying a load of #d #af #c4e #bbd watts1 #bbd #aaj #b amperes4 ,illustration3 ,,fig4 #hcg4--;,distribution with sub-feeders 7multi-center distribution74 ,the feeder connects at a central point1 ,a1 with several sub-feeders which run to distributing centers1 as at ,b1 ,c1 ,d1 and ,e4 ,with this arrangement1 compound wound dynamos may be so designed that the pressure at ,a will remain nearly uniform for all loads4 ,if1 for instance1 the wiring be proportioned for #b drop1 the dynamos may be over compounded to that extent1 and the even illumination will compensate for the extra cost in the installation4 ,the distance from the feeder junction or cut out to the electrical center of each branch circuit is #ab4e feet4 ,the compact area of distribution permits the reduction of the loss of volts to #a per cent1 or #aaj 4#ja #a4a volts drop4 ,then substituting in formula 7#e7 on page #gdh the values for amperes1 feet and drop as obtained above #b #be #ba4f ------------------------- #iha circular mils1 #a4a or a value far below that of even ,no4 #ah wire1 ,b4 ,s4 gauge 7see table on page #gca71 but the smallest wire allowed by the underwriters for the mains ,a and ,b is ,no4 #ad1 ,b4 ,s4 gauge4 ,in calculating the size of wire for the feeders the total load must be considered4 ,this is equal to eight #af candle power lamps1 requiring #c4e watts per candle power at #aaj volts #hafc4e #ddh watts #d amperes4 ,the distance from the entrance cut out to the feeder cut out is #bjj feet4 ,the drop should not be greater than #a4e per cent4 or #aaja4e #a4f volts4 ,then1 #dbjjba4f -------------------- #aj1hjj circular mils #a4f a value which indicates that ,no4 #h wire1 ,b4 ,s4 gauge1 must be used for the feeders in order to keep the drop within the limit of predetermined value4 ,,table ,,for ,,taps1 ,,bridges ,,or ,,other ,,wires ,,at ,,negligible ,,drop ---------------------------------------- ---------------------------------------- ---------------------------------------- -------------------------- ,wire ,nos4 #j #a #b #c #d #e #f #g #h #aj #ab #adafah ---------------------------------------- ---------------------------------------- ---------------------------------------- -------------------------- ,lamp ,feet#eb v4 #cjj #bfjbjjafjacjajj #hj #fe #ej #ch #bdae #i #f #aajv4#a1bhja1jhehfjfhjefjdcecdebhjbbjaf jajjfjdjbe ---------------------------------------- ---------------------------------------- ---------------------------------------- -------------------------- ,,note4--,in using this table1 it is only necessary to calculate the lamp feet of the tap and take the size of wire corresponding to the nearest greater number of lamp feet in the table4 ,the lamp feet specified by this table should not be exceeded by more than #aj per cent4 ,thus1 if a tap measure #ajh lamp feet1 in #aaj volt lamps1 ,no4 #ab wire would be used4 ,but if it measure #aae lamp feet1 it would be advisable to use ,no1 #aj wire4 ,constant ,voltage ,arc ,lamp ,circuits4--,the branch conductor should have a carrying capacity about fifty per cent4 greater than the normal current required by the lamp1 so as to provide for the heavy current required when the lamp is started4 ,the underwriters prohibit the use of any size wire under ,no4 #ab for parallel connected arc light circuits4 ,constant ,current ,series ,arc ,lamp ,circuits4--,the wiring for series connected arc lamps should never be concealed nor encased unless requested by the electrical inspector4 ,for all interior wiring of this class1 approved rubber covered wire should be used1 and the wire should always be rigidly supported on porcelain or glass insulators which will hold the wires at a distance of at least one inch from the surface wired over4 ,the wires on all circuits up to #gej volts1 should be kept at least #d inches from each other1 and #h inches apart on circuits of over #gej volts4 ,no wires carrying a current having a pressure exceeding #c1ejj volts should be carried into or over any building except central stations and sub-stations4 ,illustration3 ,,fig4 #hch4--;,diagram showing bridge wiring4 ,this method is used in the case of two parallel mains where one feeder is ample for both4 ,the feeder is run to a central point as shown and connected to the two mains by a so called bridge4 ,the arrangement clearly gives good distribution and effects a saving in copper and labor1 for if the bridge were omitted1 two feeders would be necessary4 ,wire ,calculations for ,motors4--,the proper size of wire for a motor may be readily determined by means of the following formula3 ,h4,p4 #gdf ,d #ba4f circular mils ---------------------------------------- - 7#f7 ,e ,l ,k in which ,h4,p4 horse power of motor2 #gdf watts per ,h4,p42 ,d length of motor circuit from fuse block to motor2 #ba4f ohms per foot run in circuit where wires are one mil in diameter2 ,e voltage at the motor2 ,l drop in percentage of the voltage at the motor2 ,k efficiency of the motor expressed as a decimal4 ,the average values for ,k are about as follows3 #a ,h4,p41 4#ge2 #c ,h4,p41 4#hj2 #e ,h4,p41 4#hj2 #aj ,h4,p4 and over1 #ij per cent4 ,illustration3 ,,figs4 #hci and #hdj4--,wrong and right methods of loop wiring4 ,in general1 when a large percentage of loss is allowed with lamps at short distances1 the size of wire1 calculated simply in accordance with the resistance rules1 will be found too small to carry the current safely4 ,this fact is often overlooked1 and even though wires may have been correctly calculated for a uniform percentage of loss1 they will become painfully hot simply because the table of carrying capacity was not consulted4 ,the cross connection of mains wherever possible1 for the purpose of equalizing the pressure1 will also often reduce the heating effects of the current4 ,an example of this is shown in the above figures4 ,a circle of lights was wired as in fig4 #hci1 and after the current had been turned on1 the wires of the circle became hot1 and there was quite a perceptible difference of candle power between the lights near ,a and those near ,b4 ,investigation disclosed the fact that the loop1 contrary to instructions1 had been left open4 ,a few inches of wire as shown in dotted lines remedied the fault4 ,a better arrangement1 however1 is shown in fig4 #hdj4 ,,example4--,what is the proper size of wire for a #aj ,h4,p4 motor1 run at #bbj volts1 allowable drop #b per cent4 on #bjj foot circuit4 ,substituting the given values in the formula on page #geh3 #aj #gdf #bjj #ba4f ,circular mils ---------------------------------------- - #cf1iia4 #bbj #d4d 4#i ,the nearest larger value to this result1 in the table of carrying capacities of copper wire 7page #gca71 is #da1gdj1 corresponding to ,no4 #d wire1 ,b4 ,s4 gauge4 ,in all cases the size of the wire thus formed should be compared with that allowed by the underwriters for full load current of motor1 plus #be per cent4 of that current1 and if the size calculated happen to be smaller than the allowable size1 it should be increased to the latter1 otherwise it will not pass inspection4 ,,table ,,of ,,amperes ,,per ,,motor ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------------------------- ,h4,p4 ,per ,cent4 ,eff4 ,watts ,input #ej ,volts #ajj ,volts #bbj ,volts #ejj ,volts #gj #hjj #af #g #d #b #a #gj #afjj #cb #ae #g #c #c #ge #bihj #fj #bg #ad #f #e #hj #dffj #ic #db #ba #i #g #he #fehj #acb #fj #cj #ac #aj #he #hghj #agf #hj #dj #ah #ae #he #acbjj #bfd #abj #fj #bf #bj #he #agfjj #ceb #afj #hj #ce #be #he #baijj #dch #aii #ajj #dd #cj #ij #bdijj #dih #bbf #aac #ej #dj #ij #ccbjj #ffd #cja #aea #ff #ej #ij #dadjj #hbh #cgf #ahh #hc #fj #ij #digjj #iid #deb #bbf #ii #gj #ij #ehjjj #aafj #ebg #bfd #aaf #hj #ij #ffcjj #accj #fjh #cjb #acc #ij #ij #gdfjj #adij #fgh #cci #adi #ajj #ij #hbijj #affj #gee #cgg #aff #abj #ij #iiejj #aiij #ije #dec #aii #aej #ij #abdjjj #bdhj #aacj #efd #bdh ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------------------------- ,,table ,,of ,,amperes ,,per ,,dynamo ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------------------------- ,appx4 ,appx4 ,k4,w4 #abe ,vs4 #bej ,vs4 #ejj ,vs4 ,h4,p4 ,k4,w4 #abe ,vs4 #bej ,vs4 #ejj ,vs4 ,h4,p4 #a4 #h #d #b #a4c #cj4 #bdj #abj #fj #dj4 #b4 #af #h #d #b4g #cg4e #cjj #aej #ge #ej4 #c4 #bd #ab #f #d4j #dj4 #cbj #afj #hj #ec4 #e4 #dj #bj #aj #f4g #ej4 #djj #bjj #ajj #fg4 #g4e #fj #cj #ae #aj4 #fj4 #dhj #bdj #abj #hj4 #aj4 #hj #dj #bj #ac4 #ge4 #fjj #cjj #aej #ajj4 #ab4e #ajj #ej #be #ag4 #ajj4 #hjj #djj #bjj #acd4 #ae4 #abj #fj #cj #bj4 #abe4 #ajjj #ejj #bej #afg4 #bj4 #afj #hj #dj #bg4 #aej4 #abjj #fjj #cjj #bja4 #be4 #bjj #ajj #ej #cd4 #bjj4 #afjj #hjj #djj #bfh4 ---------------------------------------- ---------------------------------------- ---------------------------------------- ------------------------------------- ,to determine the current required for a motor1 as for instance1 the #aj ,h4 ,p4 motor under consideration1 multiply the horsepower by #gdf1 and divide the product by the voltage of the motor multiplied by its efficiency as follows3 7#aj #gdf7 7#bbj 4#ij7 #cg4f amperes4 ,this value increased by #be per cent4 of itself 7#cg4f 4#be #i4d amp47 is equal to #cg4f plus #i4d #dg amperes4 ,in the table of carrying capacities of copper wire 7page #gca71 #df amperes is given as the allowable carrying capacity of ,no4 #f1 ,b4 ,s4 gauge1 rubber covered wire2 therefore ,no4 #e wire must be used4 ,calculations for ,three ,wire ,circuit4--,in all cases of interior conduit work1 and in most cases of inside open work1 the main feeders from a three wire source of supply are installed on the three wire plan1 and the sub-feeders and distributing mains1 on the two wire plan1 except where the application of the method necessitates the use of unwieldy sizes4 ,in laying out sub-feeders and mains1 the total load1 under normal operating conditions1 should be divided as nearly as possible into two equal parts1 and one part connected on each side of the neutral part of the entrance cut out1 or the neutral bus bar of the switch board or panel board in an isolated plant1 thus making the load on each side of the neutral wire of the feeder as near equal as possible4 ,fig4 #hda shows a three wire panel board with connection for #ab mains2 those shown in solid lines as ,a1 ,b1 ,c1 etc41 being connected between the neutral wire and the negative wire of the feeder1 and those shown by dotted lines as ,g1 ,h1 ,i1 etc41 being connected between the neutral wire and the positive wire of the feeder4 ,the total load consists of ninety-one #af candle power lamps1 which are so distributed that the positive wire of the feeder carries the current for #df lamps1 and the negative wire1 #de lamps1 the neutral wire carrying the difference or current for #a lamp4 ,the proper size of wire for the mains may be calculated as already explained1 but in calculating the outer wires of the three wire feeder1 the neutral wire should be disregarded and the outer wires connected as a two wire circuit carrying the total load of #ia lamps at the over all pressure of #bbj volts4 ,,example4--,ninety-one #af candle power lamps consuming #c4a watts per candle power at a pressure of #aaj volts1 will require a current of #af #c4a #ia ------------------------- #da amperes4 #aaj ,the distance from the entrance cut out to the main or feeder switch is #bjj feet1 then for a #b per cent4 drop1 or a loss of #aaj4jbb4b volts1 the cross sectional area of the wire will be1 #da amperes #bjj feet #ba4f ---------------------------------------- ---------------- #hj1eji circular mils4 #b4b volts ,illustration3 ,,fig4 #hda4--,three wire circuit panel board with connections for #ab mains4 ,the wires shown in solid lines as ,a1 ,b1 ,c1 etc41 are connected between the neutral wire and the negative wire of the feeder1 and those shown by dotted lines1 as ,g1 ,h1 ,i1 etc41 are connected between the neutral wire and the positive wire of the feeder4 ,the joint resistance of the lamps on a three wire system1 however1 would be four times greater than on a two wire system2 consequently the resistance of the outer wires of the feeder in this case will be four times greater for the same percentage of loss1 and the cross sectional area of each of the outer wires will be1 #hj1ejidbj1abg circular mils4 ,according to the underwriters' rules1 this value compels the use of ,no4 #f ,b4 ,s4 gauge wire4 ,if the lamp voltage1 #aaj volts1 be used1 the two wire formula 7#e7 given on page #gdh must be modified to1 amperes feet #ba4f circular mils ---------------------------------------- - drop #d but if an over all voltage1 7that is1 the voltage between the outer wires71 of #bbj volts be used1 the two wire formula does not require any modification4 ,the proper size of wire may also be calculated by means of the formula drop ---------------------------------------- ------- resistance per foot 4 4 4 4 7#a7 #b distance amperes ,example4--,if in calculating a three wire feeder1 the over all voltage be #bbj volts1 the drop #d4d volts1 twice the distance #djj feet1 and the current #bj4e amperes1 then1 #d4d volts ---------------------------------------- --------- 4#jjjecfe ohms per foot4 #djj feet #bj4e amperes ,in the table of the properties of copper wire which gives the resistance of various sizes of wire1 it will be noted that at all of the given temperatures ,no4 #h wire has a resistance greater than the value just calculated1 therefore1 ,no4 #f ,b4 ,s4 gauge wire should be used for the outer wires of the feeder4 ,in the table the resistance is given per #a1jjj feet1 hence it is only necessary to move the decimal point to obtain the resistance per foot4 ,if the calculation be based on the lamp voltage1 #aaj volts1 the formula 7#a7 must be modified to drop #d ---------------------------------------- -------- resistance 4 4 4 47#b7 #b distance amperes ,in this case1 drop #b4b volts1 #b distance #djj feet1 and current #da amperes1 then1 #b4b volts #d #h4h ---------------------------------------- ---------------- 4#jjecfd ohms4 #djj feet #da amp4 #af1djj ,size of the ,neutral ,wire4--,in three wire circuits1 the size of the neutral wire will depend to a great extent upon operating conditions4 ,in the case of installations which occasionally have to be worked as two wire systems1 the cross section of the neutral wire should be equal to the combined cross section of the two outer wires4 ,for interior wiring which must pass inspection1 the neutral wire must always be twice the size of one of the outside wires4 ,however1 for general distribution1 if it be reasonably sure that the system will always be worked three wire and that the drop in the two outer wires does not exceed #a per cent41 the cross section of the neutral wire may be made smaller than that of one of the outer wires4 ,in such a case the size of the neutral wire may be calculated for a maximum unbalancing of #be per cent41 when the current in one of the outer wires is #ge per cent4 of the current in the other outer wire4 ,for instance1 suppose that in a balanced system1 the total load on each of the outer wires of a feeder be #baa amperes1 and that on account of certain operating conditions1 this load has to be divided unequally so as to put #bdb amperes on one of the outer wires1 and #aha amperes on the other outer wire4 ,in this case the neutral wire will carry #fj amperes1 or #be per cent4 of the current carried by the heavier outer wire4 ,if the drop in the outer wires exceed #a per cent41 the cross section of the neutral wire will have to be equal to or larger than that of each of the outer wires1 otherwise the drop in the neutral wire will exceed volt with an unbalancing of #be per cent4 ,,chapter ,,xxxviii ,,inside ,,wiring ,the term wiring is commonly understood to mean the methods employed in laying the conductors used for the transmission and distribution of electrical energy for lighting1 power1 and other purposes4 ,interior wiring1 comprises the various methods of installing the conductors from the entrance devices in the walls or other parts of the buildings to the lamps1 motors1 and other electrical apparatus within the buildings4 ,the different methods of interior wiring may be conveniently grouped into the following general classes3 #a4 ,open or exposed wiring2 #b4 ,wires run in mouldings2 #c4 ,concealed knob and tube wiring2 #d4 ,rigid conduit wiring2 #e4 ,flexible conduit wiring2 #f4 ,armoured cable wiring4 ,open or ,exposed ,wiring4--,this method of wiring possesses the advantages of being cheap1 durable and accessible4 ,it is used a great deal in factories1 mills and buildings where the unsightly appearance of the wires exposed on the walls or ceilings is of no consequence4 ,ques4 ,what kinds of wires are suitable for this method of wiring8 ,ans4 ,either rubber covered or slow burning weather proof wire4 ,rubber insulation should always be used where the wire is in a damp place1 such as a cellar1 and either weather proof or rubber insulation may be used to protect it against corrosive vapors4 ,illustration3 ,,figs4 #hdb to #hdd4--,open or exposed wiring4 ,fig4 #hdb1 wires passing through beams4 ,the holes are bored at an angle and wire run through in zig-zag course4 ,porcelain tubes are used where the wire passes through beams2 fig4 #hdc1 cleat work across beams1 the cleats are carried by boards attached to the beams2 fig4 #hdd1 method of carrying wires on cleats around beams4 ,ques4 ,how are the wires installed8 ,ans4 ,they are laid on some cornice1 wainscoting1 beam1 or other architectural feature suitable for the purpose1 by means of porcelain knobs and cleats1 as shown in figs4 #hdb to #hdd4 ,porcelain knobs should preferably be of the two piece type 7fig4 #hfc7 in which the wire is carried between the upper and lower portions rather than being tied to a one piece knob with a tie wire as in fig4 #hfj4 ,various porcelain knobs and cleats are shown in figs4 #hfj to #hff4 ,ques4 ,what are the disadvantages of open wiring8 ,ans4 ,the wiring is not sufficiently protected from moisture1 and the effects of fire which will destroy the insulation of the wires2 it is also liable to mechanical injury4 ,illustration3 ,,figs4 #hde to #hdg4--,splicing4 ,figs4 #hde and #hdf1 making a wire splice1 and the twist completed2 fig4 #hdg1 a wrapped joint on large wire4 ,splicing of wires or joining a branch to a main wire should always be made by twisting the wires together or twisting one wire around the other1 so that the joint will be mechanically strong enough to carry all strain which may come upon it1 without any soldering4 ,the joint should then be carefully tinned and soldered in order to give good electrical contact and to avoid corrosion along the contact surface4 ,where wires are too large to be twisted together1 the ends are given a short bend and the two wires wrapped firmly together with a smaller bare copper wire1 after which the joint is thoroughly tinned and soldered1 preferably by pouring hot solder over the joint4 ,the joint is then insulated by wrapping it with two layers of pure rubber1 and three layers of tape1 sufficient to make the insulation thickness equal to that of the wire1 after which the whole joint should be painted with water proof paint4 ,ques4 ,how far apart should the wires be placed8 ,ans4 ,when installed in dry places and for pressures below #cjj volts1 the insulators should separate the wires #b inches from each other and inch from the surface along which they pass4 ,for voltages from #cjj to #ejj1 the wires should be separated four inches from each other and one inch from the surface along which they pass4 ,if the wiring be in a damp place1 the wires should be at least one inch from the surface4 ,illustration3 ,,figs4 #hdh to #hej4--;,crossing of wires4 ,where wires cross each other1 tubes should be used except in case of large stiff wires as in fig4 #hdh2 here one wire may be bent down and carried under the other2 fig4 #hdi1 short bushing strung on the wire--this method is usually unsatisfactory1 especially where a large number of wires cross each other2 fig4 #hej1 wires crossing each other through tubes4 ,flexible tubing1 such as circular loom may be used in crossing wires in dry locations4 ,insulators should always be provided where wires cross to support the wires1 thus preventing the upper wires sagging and touching those below4 ,illustration3 ,,figs4 #hea to #hec4--,methods of wiring across pipes4 ,the wires should preferably run over rather than under the pipes4 ,fig4 #hea shows crossing with circular loom1 and fig4 #heb1 one in which a tube is used4 ,both of these methods are satisfactory in the case of gas pipes1 but for steam pipes or water pipes which are liable to leak or sweat and drip moisture1 the crossing should be above as shown in fig4 #hec4 ,on side walls where vertical wires run across horizontal water pipes1 the latter should be enclosed and the moisture deflected to one side4 ,ques4 ,how should wires be protected when run vertically on walls8 ,ans4 ,they should be boxed in or run in a pipe as shown in fig4 #hed1 the covering extending #f feet above the floor4 ,when placed inside a box there should be a clearance of at least one inch around the wires2 the box should be closed at the end as shown1 and the wires protected where they enter the top with bushings4 ,when the wires are placed in a pipe they should be first encased in a piece of flexible tubing that will extend from the insulator below the end of the pipe to the first one above it4 ,illustration3 ,fig4 #hed4--,methods employed in open wiring when run vertically on walls4 ,either a box casing or iron pipe should be used to protect the wires4 ,the covering need only extend six feet above the floor4 ,ques4 ,what kind of incandescent lamp receptacle or wall socket is best adapted to exposed wiring8 ,ans4 ,one which does not have exposed contact ears1 an approved form being shown in fig4 #hei4 ,practical ,points ,relating to ,exposed ,wiring4--,some of the principal points which should be remembered in this connection1 together with the methods which may be applied to special cases1 may be briefly stated as follows3 #a4 ,in interior wiring no wires smaller than ,no4 #ad ,b4 ,s4 gauge should be used1 except as allowed by the underwriters1 and no more than #ffj watts should be allowed to a circuit4 #b4 ,tie wires should have an insulation equal to that of the conductors which they secure4 #c4 ,in all cases1 whether the wires be run on knobs1 split insulators1 or cleats1 the wires should be supported at intervals of at least #d feet1 and if exposed to mechanical injury1 the supporters should be placed at closer intervals4 #d4 ,wires run on bare ceilings of low basements1 especially where they are liable to injury1 should be protected by two wooden guard strips as shown in fig4 #heh4 ,the protective strips should be at least inch in thickness and slightly higher than the knobs1 insulators1 or cleats4 ,the two circuit wires should not be run closer than #f inches apart1 and wires run near water tanks must be rubber covered so as to render them moisture proof4 #e4 ,cleats should be used for the wiring of stores1 offices1 or buildings having flat ceilings1 provided the wiring is installed in dry locations4 #f4 ,when the installation is exposed to dampness or acid fumes such as those developed in stables1 bakeries1 etc41 the wires should run on knobs or split insulators1 and should be rubber covered4 ,illustration3 ,figs4 #hee to #heg4--,methods of carrying wires through floors4 ,in passing through floors 7or walls7 the wires often come in contact with concealed pipes or other grounded material1 hence the only way they can be properly protected is by making the bushing continuous4 ,this may consist of continuous porcelain tubes as shown in fig4 #hee1 or short bushings may be arranged in iron pipes as in fig4 #hef4 ,the method followed in case of an offset in the wall is shown in fig4 #heg4 ,sometimes the floor can be taken up and an iron conduit1 properly bent1 put in place1 the wires being reinforced with flexible tubing4 ,another method is to attach the wires to insulators2 in this case the floor must not be put down until the wiring has been examined by the inspector4 #g4 ,when wires are run at right angles to beams which are more than #d feet apart1 a running board should be used and the wires cleated to it as shown in fig4 #hdc4 ,it is desirable1 however1 to avoid the use of running boards1 whenever possible by running the wires parallel with the beams1 thus reducing the cost of insulation4 #h4 ,in factories or other buildings of open mill construction1 mains of ,no4 #h ,b4 ,s4 gauge or larger wire1 where they are not exposed to injury1 may be placed about #f inches apart and run from timber to timber1 not breaking around1 and may be supported at each timber only4 ,illustration3 ,fig4 #heh4--,method of protecting exposed wiring on low ceilings by two guard strips4 ,illustration3 ,fig4 #hei4--,receptacle suitable for use with open wiring1 the requirement being that the contact ears should not be exposed4 #i4 ,the best location for feeders is on the walls4 ,in dry buildings the fire and weather proof wire can be used with safety2 but covered wire must be used on buildings subject to any form of dampness4 ,in all cases where feeders are run on the walls1 they should be protected from mechanical injury by boxings at least #f feet high on each floor4 ,if floor switches be used1 they may be mounted on the front of the boxing4 ,in such cases1 the holes in the boxing through which the wires pass to the switches should be provided with porcelain bushings4 #aj4 ,the rosettes1 receptacles1 sockets1 snap switches1 etc41 used in connection with exposed wiring should conform in all respects to the standards specified by the underwriters4 ,illustration3 ,,fig4 #hfj to #hff4--,various porcelain knobs and cleats4 ,in open work various forms of these devices are used4 ,illustration3 ,,fig4 #hfg4--,porcelain tube for entrance of wire into a building4 ,there must be a drip loop outside to drain off water1 and the hole through which the conductor passes must be bushed with a non-combustible1 non-absorptive insulating tube slanting downward toward the outside4 ,the object of the inclination is to allow any water that might enter the tube to gravitate to the drip loop4 ,illustration3 ,,fig4 #hfh4--;,interior bushing4 ,wires must be separated from contact with walls1 floors1 timbers or partitions through which they may pass by non-combustible1 non-absorptive1 insulating tubes1 such as glass or porcelain1 except at outlets where approved flexible tubing is required4 ,bushings must be long enough to bush the entire length of the hole in one continuous piece1 or else the hole must first be bushed by a continuous water proof tube4 ,this tube may be a conductor1 such as iron pipe1 but in that case an insulating bushing must be pushed into each end of it1 extending far enough to keep the wire out of contact with the pipe4 ,wires ,run in ,mouldings4--,wooden mouldings are extensively used in connection with the wiring of stores1 factories and buildings4 ,the advantages of this type of construction are3 simplicity1 cheapness1 and accessibility1 and when the moulding is run straight and accurately mitred it makes a neat job4 ,any class of wooden moulding wiring1 however1 is not sufficiently impervious to moisture to render it suitable for use in damp places1 and it is liable to be crushed or punctured4 ,furthermore1 it is naturally very combustible4 ,these difficulties are overcome to a certain extent by impregnating the moulding with some kind of moisture repellant1 or by coating it both inside and out with water proof paint4 ,hardwood moulding should be used wherever possible1 but soft wood moulding usually conforms much better to the wall line4 ,illustration3 ,,fig4 #hfi4--,standard wooden moulding for encasing wires4 ,wooden moulding must not be used in concealed or damp places1 nor be placed directly against a brick wall where sweating may introduce moisture that may ultimately cause a short circuit4 ,wooden moulding for concealing electrical conductors is prohibited by ordinances in some cities4 ,ques4 ,for what conditions is wiring in mouldings suitable8 ,ans4 ,it is adapted to installations in which the wires have to be laid after the completion of the buildings4 ,ques4 ,describe the moulding usually employed4 ,ans4 ,it is made of hardwood in two pieces1 a backing and cap1 so constructed as to thoroughly encase the wire4 ,it should provide a one-half inch tongue between the conductors and a solid backing which should not be less than three-eighths of an inch in thickness under the grooves2 it should be able to give suitable protection from abrasion4 ,the inside of the moulding and the cap must have at least two coats of waterproof material1 or else the whole moulding must be impregnated with moisture repellant4 ,only one conductor is placed in a groove4 ,the backing is secured to the walls or ceilings by means of wire nails4 ,the wires are then laid in the grooves and the capping put in place and fastened by small brads4 ,the wires should be continuous1 and only rubber covered wire should be employed4 ,wooden moulding is made in a great variety of size and design4 ,the general appearance of this type of moulding being shown in fig4 #hfi4 ,ques4 ,what other kind of moulding is used8 ,illustration3 ,,figs4 #hgj to #hgb4--,metal moulding4 ,an approved form consists1 as shown1 of two pieces3 base 7fig4 #hgj71 and cap 7fig4 #hga71 so formed as to snap together1 the cap snapping over the base as in fig4 #hgb4 ,the entire moulding should be galvanized or coated with a rust preventive4 ,when the base is held in place by screws or bolts from the inside surface1 depressions must be provided so that the heads of the screws will be flush with the surface of the moulding4 ,ans4 ,metal moulding1 as shown in figs4 #hgj to #hgb4 ,metal moulding is permitted on circuits requiring not more than #ffj watts and where the pressure is not over #cjj volts4 ,special fittings must be used with this class of moulding so that it is continuous both mechanically and electrically4 ,the moulding should be grounded4 ,the installation rules are practically the same as those governing conduit work4 ,ques4 ,what is a kick box8 ,illustration3 ,,fig4 #hgc4--,kick box2 a device used to protect wires encased in porcelain tubes where they pass through floors4 ,ans4 ,a fitting1 as shown in fig4 #hgc1 for protecting wires at the points where they enter or emerge from the floor4 ,ques4 ,how is moulding work installed on brick or plaster walls which are liable to dampness8 ,ans4 ,a backing board must be put on before the moulding is used4 ,ques4 ,how should moulding be placed on a ceiling with respect to appearance8 ,ans4 ,the appearance is improved if the moulding be carried through to the side of the room1 even if part of it be not used4 ,this will give a neat and finished appearance to the ceiling as shown in fig4 #hgd4 ,moulding should always be run in as inconspicuous position as possible1 and if it be necessary to run it on the open ceiling1 it should be arranged so as to form regular panels4 ,often it can be run so as to take the place of a picture moulding or as a part of the baseboard so that it becomes merely a part of the wooden trim of the building2 and in certain cases it should be made of material to match the rest of the trim4 ,illustration3 ,,fig4 #hgd4--,treatment of moulding work on ceilings4 ,all installations should be planned out so as to conform to symmetrical designs1 as far as practicable with the proper distribution of the lights1 etc41 and all runs finished off1 whenever necessary1 by dead mouldings continued to the walls to improve the appearance4 ,in the figure the sectioned portions show the location of the dead moulding4 ,sometimes1 especially in the wiring of private houses the use of special moulding is necessary4 ,in such cases the shape and kind of wood should match that of the finish or trim of the room1 and the receptacles should be stained to match the moulding4 ,when the moulding is run along the walls1 the capping may be made to match the trim or the picture moulding already in place1 thus giving an apparently concealed job4 ,in this kind of work the feeders can be run through the spaces between the walls1 and if flexible tubes such as circular loom or flexiduct be used1 no splice box will be necessary where the system of wiring changes and single braided rubber wire may be used throughout4 ,ques4 ,what is the usual character of moulding work8 ,ans4 ,usually1 a certain part of the work will be run as concealed1 that is1 inside the partitions1 the wires being fished from the moulding to the outlet4 ,practical ,points ,relating to ,wiring in ,mouldings4--,the following practical points will be found useful in the satisfactory execution of any class of wiring with wooden moulding3 #a4 ,wooden moulding should never be concealed1 and should not be used in damp places or in buildings subject to acid fumes1 such as ice houses1 breweries1 or stables1 etc4 #b4 ,wooden moulding selected for use should be formed of good straight stock and free from knots1 knot holes and other imperfections4 ,the saving effected in the lower cost of second hand moulding does not compensate for the additional cost increase in its working4 #c4 ,when wooden moulding is used in connection with solid pipe or flexible tube conduit1 an iron box or conduitlet must be installed where the system of wiring changes1 as shown in fig4 #hge4 ,the pipe conduit is secured to the box by means of lock nuts1 with porcelain bushings or flexible tubes protecting the wires4 ,in all cases the loom should run up to the moulding4 ,illustration3 ,,fig4 #hge4--,method of tapping outlets for feeder circuits when wiring with wooden moulding4 ,arc ,light ,wiring4--,all wiring for high voltage arc lighting circuits should be done with rubber covered wire4 ,the wires should be arranged to enter and leave the building through an approved double contact service switch which should close the main circuit and disconnect the wires in the building when turned off and be so constructed that they will be automatic in their action1 not stopping between points when started and to prevent arcing between points under any circumstances1 and should indicate plainly whether the current is on or off4 ,never use snap switches for arc lighting circuits4 ,all arc light wiring of this class should be in plain sight and never enclosed1 except when required1 and should be supported on porcelain or glass insulators which separate the wires at least one inch from the surface wired over4 ,the wires should be kept rigidly at least eight inches apart1 except1 of course1 within the lamp1 hanger board or cut out box or switch4 ,on side walls1 the wiring should be protected from mechanical injury by a substantial boxing1 retaining an air space of one inch around the conductors1 closed at the top 7the wires passing through bushed holes7 and extending not less than seven feet from the floor4 ,when crossing floor timbers in cellars or in rooms1 where they are liable to be injured1 wires should be attached by their insulating supports to the under side of a wooden strip not less than one-half an inch in thickness4 ,arc ,lamps on ,low ,pressure ,service4--,for this service there should be a cut out for each lamp or series of lamps4 ,the branch conductors for such lamps should have a carrying capacity about #ej per cent4 in excess of the normal current required by the lamp or lamps to provide for the extra current required when the lamps are started or should a carbon become stuck without over fusing the wires4 ,if any resistance coils be necessary for adjustment or regulation1 they should be enclosed in non-combustible material and be treated as sources of heat2 it is preferable that such resistance coils be placed within the metal framework of the lamp itself4 ,incandescent lamps should never be used for resistance devices4 ,these lamps should be provided with globes and spark arresters1 as in the case of arc lamps on high voltage series circuits1 except when the closed arc lamps are used4 #d4 ,wooden moulding should never be run in elevator shafts1 or shafts of any kind1 and should never be run on the inner side of the outside walls of the buildings1 as these locations are usually subject to dampness4 #e4 ,in laying out feeders it is usually cheaper to use iron conduit in a shaft1 than to run moulding through the floor timbers4 #f4 ,when tapping outlets for feeder circuits1 an iron outlet box with cover should be used1 as shown in fig4 #hhf4 ,the one splice box is held up to the outlet box already installed by means of two long screws1 and the loom is run right up to the moulding so as to leave no exposed wire4 ,illustration3 ,,fig4 #hgf4--;,circular fixture block for outlet from moulding work on ceiling4 #g4 ,wherever fixture outlets are installed1 a circular fixture block as shown in fig4 #hgf should be used1 to give a good support for the fixture and to make a neat backing for the fixture canopy4 ,the wires should be brought through the fixture without cutting and disfiguring the canopy4 ,concealed ,knob and ,tube ,wiring4--,this method of wiring should be discouraged as far as possible1 as it is subject to mechanical injury1 is liable to interference from rats1 mice1 etc4 ,as the wires run according to this method are liable to sag against beams1 laths1 etc41 or are likely to be covered by shavings or other inflammable building material1 a fire could easily result if the wires become overheated or short circuited4 ,illustration3 ,,fig4 #hgg4--;,concealed knob and tube wiring4 ,the wires are carried on porcelain knobs attached to the beams4 ,if run perpendicular to the beams1 holes are bored in the latter and porcelain tubes with a shoulder at one end1 inserted in the holes through which the wires pass4 ,the knobs should support the wires at least one inch from the surface over which they run1 and should not be spaced further than #d feet apart4 ,the wires should be attached with tie wires having an insulation equal to that of the conductor which it secures to the knob4 ,the use of split knobs does away with the necessity of using tie wires4 ,the conductors must be at least #e inches apart and it is better to support them on separate beams when possible4 ,each wire must be encased in a piece of flexible tube at all switches1 outlets1 etc41 and this piece of tubing should be sufficiently long to extend from the last insulator and project at least one inch beyond the outlet4 ,concealed knob and tube wiring is still allowed by the ,underwriters1 although many vigorous attempts have been made to have it abolished4 ,each of these attempts has met with strong opposition from electric light companies and contractors1 especially in small villages and towns the argument being that it is the cheapest method of wiring1 and if forbidden1 many places which are wired according to this method would not be wired at all1 and the use of electricity would therefore be much restricted1 if not entirely dispensed with in such communities4 ,this argument1 however1 is only a temporary makeshift obstruction against progress1 and in the near future1 no doubt1 concealed knob and tube wiring will be forbidden by the underwriters4 ,illustration3 ,,figs4 #hgh to #hhj4--,methods of making fixture outlets in concealed knob and tube wiring4 ,a cleat consisting of a piece of board at least in4 thick1 should be nailed between the joists or studs into which the wood screws supporting the electrolier can be secured4 ,holes are then bored through the cleat1 through which the flexible tubing can pass4 ,with a combination gas and electric fixture as shown in fig4 #hgi1 no cleat is necessary1 because the gas pipe supports the fixture4 ,the flexible tubing should be wired to the gas pipe1 to prevent displacement by artisans who have occasion to work around the outlet4 ,ques4 ,describe the method of concealed knob and tube wiring4 ,ans4 ,it consists in running the wires concealed between the floor beams and studs of a building1 knobs being used to support the wires when run parallel to the beams or studs1 and porcelain tubes1 when run at right angles through the beams1 or studs as shown in fig4 #hgg4 ,in this method of wiring1 usually nothing need be disturbed on the first floor as the various outlets can be reached from the basement and from the second floor4 ,illustration3 ,,fig4 #hha and #hhb4--;,arrangement of switch and receptacle outlets in knob and tube wiring4 ,in wiring for switches1 flexible tubing must be used on the conductor ends from the last porcelain support1 as shown1 the same as on conductor ends for other outlets4 ,a pressed steel switch box should be used to encase each flush switch mechanism1 even though it already be encased in porcelain4 ,a in4 wood cleat or cleats are arranged to support the switch box4 ,these wooden cleats should not be set out flush with the outer edges of the studs1 but should be set about in4 back1 as illustrated1 to allow a space in which the plaster can take a grip4 ,for instance1 if it be necessary to make an outlet for the center fixture in the parlor1 a strip of flooring can be removed from the floor above so as to expose the beams4 ,then the wireman can bore two holes through each of the beams1 insert porcelain tubes therein1 slip the wires through the outlet and replace the strip of flooring4 ,various simple methods may be employed for carrying the wires to the outlets on the side walls4 ,for example3 a small hole can be made in the wall1 and the wire may be dropped through the spaces between the walls1 or they may be pulled up from the basement by means of a cord lowered with a weight attached to its end4 ,outlets for switches and base receptacles may be provided for1 in a similar manner4 ,illustration3 ,,figs4 #hhc and #hhd4--;,elevation and sectional view showing arrangement of switch outlet in concealed knob and tube wiring4 ,illustration3 ,,fig4 #hhe4--;,arrangement of surface switch in concealed knob and tube wiring4 ,for a surface snap switch outlet1 an iron box is not necessary1 but a in4 cleat must be installed to hold the tubing in place and to provide a proper support for the screws that hold the switch4 ,in wiring old buildings where supporting cleats were not provided back of the plaster1 a in4 wooden block or plate should be installed on the surface1 to which the switch can be attached4 ,ques4 ,what are the advantages of concealed knob and tube wiring8 ,ans4 ,its cheapness1 especially in wiring completed buildings1 and the absence of any wires or casings on the walls or ceilings4 ,ques4 ,what kind of wire must be used8 ,ans4 ,wire having an approved rubber insulating covering4 ,illustration3 ,,figs4 #hhf to #hhh4--,switch boxes for concealed knob and tube wiring4 ,these are for flush switches and are formed from sheet steel4 ,a single switch box can be expanded for any number of switches1 by using the proper number of spacers4 ,single and double switch boxes can be supplied already assembled and are used where feasible1 because it is cheaper to buy them this way than to assemble them4 ,holes partially punched1 which can be knocked out with a hammer blow1 are provided in the sides and back through which the flexible conduit wire protection can be extended4 ,rigid ,conduit ,wiring4--,the installation of wires in conduits not only affords protection from mechanical injury1 but also reduces the liability of a short circuit or ground on the wires producing an arc which would set fire to the surrounding material2 the conduit being of sufficient thickness to blow a fuse before the arc can burn through the conduit4 ,ques4 ,describe the unlined type of conduit4 ,ans4 ,it consists of an iron or steel pipe1 similar in size1 thickness1 and in every other way to gas pipe1 except that special precautions are taken to free it inside from scale or any irregularities2 it is then coated inside with enamel1 outside it is sometimes enameled and sometimes galvanized4 ,ques4 ,describe the lined type of conduit4 ,ans4 ,it usually consists of a plain iron pipe lined with a tube of paper which has been treated with an asphaltic or similar compound2 this paper tube is cemented or fastened to the inside of the iron pipe so that it forms practically an integral part of the same4 ,ques4 ,what are the advantages of unlined conduit8 ,ans4 ,it is cheaper1 because having no lining a smaller size of conduit can be used for any given size of conductor2 it is also cheaper to install1 as it can be bent1 threaded1 and cut more readily than the lined conduit4 ,wires may be more easily inserted and withdrawn as the inside is smoother than that of the lined conduit4 ,,note4--,conduits for inside wiring which are subject to inspection1 must have an inside diameter of not less than inch4 ,they must be continuous from outlet to outlet or to junction bores1 and must properly enter and be secured to all fittings1 and the entire system be mechanically secured in position4 ,in case of service connections and main wires1 this involves running each conduit continuously into a main cut out cabinet or gutter surrounding the panel board as the case may be4 ,conduits must first be installed without the conductors1 and be equipped at every outlet with an approved outlet box or plate4 ,outlet plates must not be used where it is practicable to install outlet bores4 ,the outlet box or plate must be so installed that it will be flush with the finished surface1 and if this surface be broken1 it shall be repaired so that it will not show any gaps or open spaces around the edge of the outlet box or plate4 ,in buildings already constructed where the conditions are such that neither outlet box nor plate can be installed1 these appliances may be omitted by special permission1 providing the conduit ends are bushed and secured4 ,it is suggested that outlet boxes and fittings having conductive coatings be used in order to secure better electrical contact at all points throughout the conduit system4 ,metal conduits where they enter junction boxes1 and at all other outlets1 etc41 must be provided with approved bushings or fastening plates1 fitted so as to protect wire from abrasion1 except when such protection is obtained by the use of approved nipples1 properly fitted in boxes or devices4 ,conduits must have the metal of the conduit permanently and effectually grounded4 ,conduits and gas pipes must be securely fastened in metal outlet boxes so as to secure good electrical connections4 ,if conduit1 couplings1 outlet boxes or fittings having protective coating of insulating material1 such as enamel1 be used1 such coating must be thoroughly removed from threads of both couplings and conduit and from surfaces of boxes and fittings where the conduit is secured in order to obtain requisite good connection4 ,where boxes used for centers of distribution do not afford good electrical connection1 the conduits must be joined around them by suitable bond wires4 ,where sections of metal conduit are installed without being fastened to the metal structure of buildings or grounded metal piping1 they must be bonded together and joined to a permanent and efficient ground connection4 ,junction boxes must always be installed in such a manner as to be accessible4 ,all elbows or bends must be so made that the conduit or lining of same will not be injured4 ,the radius of the curve of the inner edge of any elbow must not be less than three and one-half inches4 ,must have not more than the equivalent of four quarter bends from outlet to outlet1 the bends at the outlets not being counted4 ,illustration3 ,,fig4 #hhi4--;,conduit box showing arrangement for combination side outlet with open cover4 ,outlet or junction boxes are of two general types3 #a1 those which are made for a particular position and have a given number of outlets1 and #b1 those which have a variable number of outlets which are plugged with metal discs in such a manner that the latter can be knocked out by a slight blow of a hammer4 ,the illustration shows a universal plugged steel conduit box1 which can be used as a straight electric1 or combination gas and electric1 ceiling or side wall outlet1 or for flush rotary or push button switches1 or for flush receptacles4 ,when rigid conduits are used1 they are screwed to the outlets by means of lock nuts and washers4 ,in the case of flexible conduits1 the entering ends of the conduits are provided with clamp bushings which are secured to the outlet by means of lock nuts4 ,all outlet boxes are fitted with covers of various designs1 which permit their use for various types of construction such as ceiling and wall work in lath or plaster1 fireproofing ceiling work1 etc41 while many designs of outlet plates and receptacle plates may be obtained from the supply houses to satisfy the requirement of any special case4 ,ques4 ,what are the disadvantages of the unlined conduit8 ,ans4 ,the ,underwriters require the use of double braided conductors instead of single braided which are allowed for lined conduits4 ,ques4 ,where may unlined conduits be used8 ,ans4 ,in buildings where the conduit is not liable to corrosive action4 ,flexible ,conduit ,wiring4--,flexible conduits are used to advantage in many cases where rigid conduits would not be desirable4 ,it is especially adapted to completed buildings where it is desired to install the wiring by fishing without greatly disturbing the walls1 floors1 or ceilings4 ,illustration3 ,,figs4 #hij and #hia4--;,greenfield flexible steel conduit2 fig4 #hij single strip type2 fig4 #hia double strip type4 ,the former 7fig4 #hij7 is formed with a single strip of galvanized steel1 interlocked and gasketed in such a manner as to be suitable for concrete construction4 ,the double strip type 7fig4 #hia7 is constructed of a concave and convex steel strip1 spirally wound upon each other in such a manner as to interlock their concave surfaces4 ,thus the convex surfaces of the two strips form respectively the outer and inner surfaces of the conduit4 ,this construction insures a smooth interior surface1 thus reducing the possibility of friction in the drawing in of conductors4 ,a gasket is provided between the inner and outer strips rendering the conduit moisture proof4 ,this form of flexible conduit is especially adapted to use where the wiring is installed after completion of building1 because it is very flexible4 ,ques4 ,how is a flexible conduit installed by fishing8 ,ans4 ,it is fished under floors1 in partitions between the floor and ceiling1 by making pockets in the floors1 walls or ceilings1 say every #ae or #bj feet1 and fishing through first a stiff metal wire called a snake1 and then attaching the conduit to same and pulling the conduit in place from pocket to pocket4 ,illustration3 ,,fig4 #hib4--;,insulating joint4 ,this fitting is used in fixture work4 ,the part ,a screws on to the gas pipe and ,b to the fixture4 ,the parts are separated by insulating material ,e1 and the outside of the joint is covered with moulded insulation ,d4 ,in connecting fixtures to the wiring1 all wires should be kept away from the gas pipe above the joint1 but they may be bunched in below the insulating joint after the wires have been spliced1 soldered1 and taped4 ,it is important to protect the gas pipe at this point4 ,insulating joints should be tested before being used4 ,illustration3 ,,fig4 #hic4--;,canopy insulator4 ,this fitting should be installed wherever there are metal ceilings against which the canopies of fixtures might come4 ,the canopy is the brass cup shaped piece used at the top of fixtures to cover the joint1 and is simply an insulating ring placed between the canopy and the ceiling4 ,it is in contact with the fixture2 hence1 it is important that it be insulated from metal ceilings1 or else all the benefits derived from an insulating joint will be lost4 ,ques4 ,how is the conduit fished on vertical runs8 ,ans4 ,a chain or weighted string is used which is dropped from the outlet to the floor and its lower end located by sound of the chain end or weight striking the floor4 ,illustration3 ,,fig4 #hid4--,section of flooring illustrating use of fishing hook4 ,in fishing wires1 punch a hole through the plastering at the required position1 being careful that there is no studding at that place4 ,use a brad awl and cut the hole large enough to permit running of the wires4 ,with a short length of small brass spring wire1 push through the opening a few inches of number #ai double jack chain such as is used for general fishing purposes1 first having connected the end of the chain with a piece of heavy linen thread4 ,run out the thread between the laths and the outside wall until the chain touches the floor beneath2 move the thread and locate the chain by the sound2 bore a hole through the baseboard or floor1 as the case may be1 toward the chain4 ,use a two or three foot ,german twist gimlet4 ,with a small brass spring wire bent at the end in the shape of a hook1 fish for the chain and draw it out4 ,at the other end of the thread attach the wire and draw it through with the thread4 ,passing under the floor bore a second hole through the floor as near the other as possible4 ,run into this a piece of snake or fishing wire with a hook at the end1 until it comes to an obstruction4 ,locate the obstruction by sound4 ,in running wires under the flooring first carefully examine all parts and find the direction in which the beams and timbers run1 and run the wires parallel with these4 ,after locating the end of the fishing wire see if the obstruction be a timber2 if so1 find the center and bore from the middle diagonally through it in the direction of the fishing wire4 ,drop the jack chain and thread through the hole2 fish for it and draw it through hole number #b2 attach the insulated wire and draw it back4 ,starting hole number #c1 bore hole number #d diagonally through the timber in the direction in which the wire is to be run1 making holes #c and #d form an inverted ,v through the timber4 ,run the fishing wire through hole number #d until it meets an obstruction4 ,if at the end of the room1 bore through the floor1 drop the chain1 fish it out1 attach wire and draw it home4 ,putty up holes after having finished the work1 in case of hard finish1 plug them up with wood4 ,in lightly built houses it is often found easier to take off the moulding above the baseboard and run the wire under it4 ,in such cases care should be taken to break off the old nails1 as any attempt to drive them out would cause a bad break4 ,in closets and around chimneys it is usually found easy to work4 ,a mouse or lead weight attached to a string may often be dropped from the attic to the cellar ceiling through the space outside the chimney4 ,ques4 ,what is the difference between flexible conduit and flexible tubing8 ,ans4 ,flexible conduits are made of metal while flexible tubing is non-metallic4 ,ques4 ,describe a flexible conduit4 ,ans4 ,it is a continuous flexible steel tube composed of convex and concave metal strips1 wound spirally upon each other in such a way as to interlock their concave surfaces4 ,ques4 ,what are the advantages of this form of flexible conduit8 ,ans4 ,it possesses considerable strength and can be obtained in long lengths 7#ej to #bjj feet72 elbow fittings are not required as the conduit may be bent to almost any radius4 ,the fissures of the conduit provide some ventilation2 this is an advantage in some places and a disadvantage in others4 ,illustration3 ,,figs4 #hie to #hig4--;,greenfield flexible steel conduit and fish plug1 showing method of insertion4 ,fish plugs are made for inch1 inch1 and inch conduit and are useful in drawing in the conduit in finished buildings where it is desired to fish it under doors or in partitions4 ,after the conduit has been cut off square in the special vise1 the fish plug may be screwed into the tube and the fish wire or drawing-in line should then be attached to the eyelet on the end of the plug4 ,ques4 ,in what places are flexible conduits not desirable8 ,ans4 ,in damp places4 ,ques4 ,why8 ,ans4 ,because of the fissures4 ,practical ,points ,relating to ,inside ,conduit ,wiring4--,the following instructions apply to the installation of wiring in both rigid and flexible conduit3 #a4 ,all conduits should be made continuous from one junction or outlet box to another1 or to the various fixtures4 ,a conduit installation is made a complete system by the use of outlets1 outlet boxes1 switch or junction boxes1 and panel boxes with doors and locks1 which serve to thoroughly protect the circuit at all points4 ,illustration3 ,,figs4 #hih to #ija4--,pull boxes and their use in conduit work4 ,a pull box is a convenient device used for the purpose of avoiding the disadvantages of having too many bends in one continuous line of conduit2 too many bends will give trouble when the conductors are drawn in4 ,pull boxes are also useful in places where the arrangement of the conduit is such that trouble would be experienced in bending it to a fit1 and also in the case of conduits which are first run on a side wall and then have to be carried across the ceiling at right angles to the wall4 ,fig4 #hih shows an example of objectionable bends1 and fig4 #hii1 the method of overcoming the difficulty by the use of a pull box4 ,it is evident that it would be impossible to make some of these bends so as to permit the drawing in of the conductors4 ,this difficulty is overcome1 as shown1 by placing a pull box on the wall1 with its top close to the ceiling4 ,a board ,b1 having the proper size holes for the conduits is fastened to the front of the box and close to the ceiling4 ,after the conductors have been drawn into the conduits along the wall as far as the pull box1 they can be readily pulled away from the box through the holes in the board into the corresponding conduit on the ceiling4 ,fig4 #ija1 shows the use of a pull box in a case where it is necessary to run conduit through partitions at right angles to each other4 ,pull boxes can be designed to suit any condition liable to occur in practice1 and when properly used will always save much time and labor4 ,locknuts should be placed on the ends of all conduits1 both inside and outside the pull box in order to prevent their being displaced when drawing in the conductors4 ,after all the conductors have been drawn into the conduit1 all the outlets should be plugged up with wood or fibre plugs made in parts to fit around the wires and cables1 and the outlets given a coating of some compound which will render the whole system air tight and moisture proof4 ,a final test should then be made to ascertain that there are no grounds on the different parts of the wiring1 and that the insulation comes up to the requirements of the underwriters4 ,the metal of all conduits1 and the sheathing of steel armoured cables should be effectually and permanently grounded4 #b4 ,in the installation of interior conduit wiring1 the tubes are usually put in place as soon as the partitions of the buildings have been constructed4 ,in non-fireproof buildings1 the tubes are usually supported from the underside of the floor beams1 but in fireproof buildings they are placed on top of the floor beams and under the floor as in fig4 #ijb4 #c4 ,when conduit is used in damp places1 lead encased wires should be used1 and the wires drawn in very carefully so as to prevent any injury to the casings4 #d4 ,for wiring installations in buildings constructed entirely of reinforced concrete1 the preliminary work should be laid out during the progress of the building operations so as to avoid1 as much as possible1 the necessity of drilling holes in the finished concrete work4 ,illustration3 ,,fig4 #ijb4--,method of installing conduits in fire proof buildings4 ,the installation of the conduit includes the placing of all outlet boxes1 and when this has been completed1 the lathing or plastering work is executed1 and after that is finished1 the wire is pulled into the tubes1 and the receptacles1 switches1 etc41 put in position4 ,the work of pulling in the wires may be greatly facilitated by the use of pull boxes as shown in figs4 #hii and #ija4 #e4 ,for concealed wiring1 the location of all the outlets should be marked by sheet iron tubes large enough to hold the conduits4 ,these tubes should be properly plugged1 and set in the false work before the concrete is poured in4 ,in a similar manner1 threaded pieces of conduit of the proper size1 should be placed in the false work for risers4 #f4 ,for exposed wiring on concrete walls and ceilings1 suitable cast iron supports should be set in the moulds at regular intervals4 ,when liberally used1 these supports will also serve as good supports for other pipes4 #g4 ,where a conduit line terminates on the outside of a building some suitable fitting such as a pipe cap should be used1 as shown in fig4 #ijc1 to prevent the entrance of moisture into the conduit system4 ,a variety of devices suitable for this purpose are available at supply houses2 but those having porcelain covers which spread the wires the proper distance apart are the most satisfactory4 #h4 ,where it is desirable or necessary to continue open wiring from conduits1 or where the character of the wiring makes it necessary to bring the wires over from the conduit1 as in an arc lamp1 neat and safe work can be done by use of a suitable form of condulet as shown in fig4 #ijd4 ,illustration3 ,,fig4 #ijc4--,service entrance to interior conduit system2 showing method of preventing moisture reaching the interior of the conduit system4 ,illustration3 ,,fig4 #ijd4--,outlet to arc lamp from conduit by use of condulet4 ,the wires are brought out from the conduit system at a distance of #b inches apart4 ,conduits are made in a great variety of design with interchangeable porcelain covers which render them adaptable to almost all cases requiring the installation of outlet boxes4 #i4 ,where a conduit line terminates in a switch or panel box1 the lining or casing of the panels should be of iron1 and the conduit firmly secured to it so as to make good electrical contact4 ,vertical lines of conduit should be fastened to the wall or other supports in such a manner as to prevent the weight of the conduit coming on the panel box1 and each length of conduit installed should be fastened so as to bear only its own weight4 ,the best method of fastening conduit to brick walls is by the use of expansion bolts and screws4 ,in the case of fire brick ceilings or other plastered walls1 toggle bolts should be used4 ,when conduits are run on wooden or iron beams1 various kinds of pipe hanger may be employed4 #aj4 ,there are numerous devices on the market for bending conduit for the making of elbows1 offsets1 etc41 but the majority possess the disadvantage that the conduit must be taken to them to be bent4 ,in the case of the smaller sizes1 this difficulty is avoided by the use of some form of conduit bender such as shown in figs4 #iaj and #iaa4 ,illustration3 ,,figs4 #ije to #iji4--,sprague multilet covers4 ,fig4 #ije1 six wire porcelain cover2 #ijf1 ,p ,s4 rec4 cover2 #ijg1 cover for five ampere snap switch2 #ijh1 ,g4 ,e4 and ,p4 ,s4 rec4 cover2 #iji1 cover for ten ampere snap switch4 #aa4 ,in all cases1 the interior diameter of the conduit installed should be amply sufficient to permit of the wires being drawn in easily1 thus providing a substantial raceway for the conductors4 ,the practice of pulling wires through conduit by means of a block and tackle is very objectionable4 ,it is evident that if the wires be pulled in by the application of much force the insulation is very liable to become damaged2 furthermore1 much difficulty will be experienced in pulling them out again1 especially in warm places where the heat tends to soften the lining of the conduit1 and also the rubber covering of the wire4 ,powdered soapstone put in the pipe while the wires are being drawn in will lessen the friction and permit the wire to go in more readily4 ,illustration3 ,,fig4 #iaj4--,ordinary form of hickey or conduit bender4 ,it consists of a piece of one inch steam pipe about three feet long with a one-inch cast iron tee screwed onto one end of the pipe4 ,this device is used as follows3 the conduit to be bent is placed on the floor and the tee slipped over it4 ,the workman then places one foot on the conduit close to the tee1 and pulls the handle of the bender towards him4 ,as the bending progresses1 the workman should take care to continually move the bender away from himself1 to prevent the buckling of the conduit4 ,illustration3 ,,fig4 #iaa4--;,commercial form of hickey or conduit bender4 ,illustration3 ,,figs4 #iab and #iac4--,methods of bending large conduits4 ,a substantial support is necessary which may consist1 as in fig4 #iab1 of two pieces of #b #d studding ,a and ,b securely fastened to an upright4 ,the conduit is placed under the block ,a and over the block ,b1 and then bent by a downward pressure exerted at ,c1 the conduit in the meantime being gradually advanced in the direction ,d to give a curve of the required radius4 ,the method shown in fig4 #iac1 may be used wherever a ring ,a can be attached to a beam or girder by means of clamps or otherwise to serve as a support4 ,in this case the conduit is slipped through the ring and placed on the top of blocking ,b4 ,the bending is accomplished by means of a block and tackle rigged to an overhead beam as shown4 ,where ring supports cannot be arranged1 the application of frame bending methods give the most satisfactory results4 ,armoured ,cable ,wiring4--,where a conduit system cannot be conveniently installed1 armoured cable is used4 ,armoured cable is made by winding steel strips over the insulated conductors1 the latter being permanently retained inside the steel casing4 ,armoured cable is manufactured in long lengths1 the actual lengths being determined by convenience in handling4 ,illustration3 ,,figs4 #iad and #iae4--;,greenfield flexible steel armoured conductors4 ,the armour is composed of convex and concave galvanized metal strips1 wound spirally upon each other and over the insulated conductors4 ,a gasket is placed between the inner and outer metal strips1 thus further rendering the conductor moisture proof4 ,,fig4 #iaf4--;,greenfield flexible steel armoured lead covered conductors for use in wet places1 such as breweries1 packing houses1 cold storage buildings1 coal breakers and the like1 and for underground construction1 in which classes of work these materials are being extensively and satisfactorily used4 ,ques4 ,what are the features of armoured cable8 ,ans4 ,it is flexible and the conductors are well protected from mechanical injury4 ,while this form of wiring has not the advantage of the conduit system--namely1 that the wires can be withdrawn and new wires inserted without disturbing the building in any way whatever--yet it has many of the advantages of the flexible steel conduit1 and it has some additional advantages of its own4 ,for example1 in a building already erected1 this cable can be fished between the floors and in the partition walls1 where it would be impossible to install either rigid conduit or flexible steel conduit without disturbing the floors or walls to an extent that would be objectionable4 ,illustration3 ,,figs4 #iag to #ibj4--;,greenfield flexible conduit tools4 ,special tools are necessary for installing this type of conduit4 ,fig4 #iag1 universal reamer2 fig4 #iah1 bushing tool2 fig4 #iai1 cable armour cutter2 fig4 #ibj1 vice for holding conduit4 ,to remove cable armours1 clamp the conductor firmly in the armour cutter and with a pair of cutting pliers back the armour off1 one strip at a time1 to the point of contact with the cutting edge of the tool4 ,the vise for holding conduit takes all sizes4 ,the conduit can be cut with an ordinary hacksaw4 ,to protect the insulation against any possible injury while the wire is being drawn in1 a soft metal bushing should be inserted in the end of the tube and secured permanently thereto by means of the bushing tool4 ,the bushing provided for this purpose has an outside thread1 which permits its being screwed into the end of the tube and then expanded by the use of the tool4 ,the tool should always be used after the bushing has been screwed into the pipe1 then the bushing tool should be inserted4 ,ques4 ,how should armoured cable be installed8 ,ans4 ,it should be continuous from outlet to outlet1 without being spliced and installed on the loop system4 ,outlet boxes should be installed at all outlets1 although1 where this is impossible1 outlet plates may be used under certain conditions4 ,clamps should be provided at all outlets1 switch boxes1 junction boxes1 etc41 to hold the cable in place1 and also to serve as a means of grounding the steel sheathing4 ,ques4 ,is armoured cable wiring expensive8 ,ans4 ,it is less expensive than the rigid conduit or the flexible steel conduit1 but more expensive than cleat wiring or knob and tube wiring1 and is strongly recommended in preference to the latter4 ,,chapter ,,xxxix ,,outside ,,wiring ,in the equipment of lighting and power plants1 the cost of the outside wiring represents a considerable proportion of the total investment1 sometimes costing more than the engines1 boilers and dynamos4 ,a thorough knowledge of outside wiring is therefore necessary to properly proportion and install the wires so that the system will prove economical and safe4 ,materials for ,outside ,conductors4--,copper wire is now considered to be the most suitable material not only for the transmission of current for electric light and power purposes1 but also for telegraph and telephone lines1 in place of the iron wire formerly employed4 ,hard drawn copper wire is used in outside construction1 because its tensile strength ranges from #fj1jjj to #gj1jjj pounds or about twice that of soft copper4 ,this is desirable to withstand the stresses to which the wire is subjected which1 in the case of long spans1 are considerable4 ,the table on the next page gives the tensile strength1 in pounds per square inch of cross section1 hard drawn copper wire of various sizes ,b4 ,s4 gauge4 ,the metal aluminum possesses certain advantages as a material for overhead wires4 ,its conductivity is about 4#f that of copper4 ,the specific gravity of aluminum is about #b4g1 while that of copper is #h4hi1 so that a given volume of copper will weigh #c4c times more than an equal volume of aluminum1 and copper wire of given length and resistance would be about twice as heavy as an aluminum wire of equal length and resistance4 ,there are several disadvantages1 such as1 low tensile strength1 high electro-positive quality of the metal1 higher electrostatic capacity1 etc4 ,,tensile ,,strength ,,of ,,copper ,,wire ---------------------------------------- ---------------------------------------- ---------------------------------------- -- ,size of wire ,tensile ,size of wire ,tensile ,b4 ,s4 gauge strength1 lbs4 ,b4 ,s4 gauge strength1 lbs4 ---------------------------------------- ---------------------------------------- ---------------------------------------- -- #jjjj #iiga #i #fag #jjj #gijg #aj #dhi #jj #fbga #aa #chh #j #digc #ab #cjg #a #cidc #ac #bdd #b #cabg #ad #aic #c #bdhj #ae #aec #d #aifg #af #acc #e #aeei #ag #ig #f #abcg #ah #gg #g #ihj #ai #fa #h #ggh #bj #dh ---------------------------------------- ---------------------------------------- ---------------------------------------- -- ,pole ,lines4--,in the majority of cases overhead conductors are supported by wooden poles4 ,in tropical countries1 however1 such as ,india1 ,central ,america1 etc41 where wood is rapidly destroyed by the ravages of white ants and other insects1 iron poles are almost exclusively used for telegraph1 telephone1 and other electric transmission lines4 ,the form of iron pole generally adopted consists of tapering shells of sheet iron of convenient length1 riveted together at their ends and set into cast iron base plates which are buried in the ground4 ,illustration3 ,,figs4 #iba to #ibi4--,pole construction tools4 ,fig4 #iba1 long handled digging shovel2 fig4 #ibb1 digging bar2 fig4 #ibc1 crow and digging bar2 fig4 #ibd1 tamping and digging bar2 fig4 #ibe1 wood handle tamping bar2 fig4 #ibf1 slick digging tool2 fig4 #ibg1 post hole augur2 fig4 #ibh1 carrying hook2 fig4 #ibi1 tamping pick4 ,wooden ,poles4--,on account of their size and straightness1 various species of northern pine1 cedar and cypress are especially suitable for large poles4 ,chestnut1 which can be readily sawed and hewed is a very good material for smaller poles4 ,sawed redwood is extensively used in ,california4 ,preservation of ,wooden ,poles4--,the preservation of wooden poles employed in line work is a matter of importance4 ,decay of the pole at or near the soil line is caused primarily by various forms of bacteria or fungi1 and in some cases by insects4 ,bacteria and fungi attack either dead or living timber4 ,in the case of dead timber1 such as that of poles1 they attack the walls of the cells and cause the familiar rot or decay which eventually destroys the usefulness of the pole4 ,it is well known that the rapid multiplication or action of the bacteria and the growth of the fungi are induced by a certain per cent4 of moisture and the heat of the sun1 that is1 the portion of the pole at or near the soil line is alternately moistened and dried4 ,therefore1 in order to protect it against this action1 it is necessary to sterilize the pole by the application of an antiseptic which will penetrate the pores of the wood4 ,preservation ,processes4--,there are several processes which may be successfully employed for the preservation of poles or other exposed timber4 ,the best known of these are the creosoting1 burnettizing1 kyanizing1 carbolizing1 and vulcanizing processes4 ,in ,england1 creosoted poles showed no sign of decay at the end of #ce years of service4 ,in the ,united ,states they have an average life of #bb years4 ,in ,europe impregnation with copper sulphate has been extensively used1 but this impregnation must take place within a few days after cutting down the tree4 ,uniformly good results have been obtained by impregnation with corrosive sublimate1 involving simply immersion in the liquid from ten to fourteen days4 ,german authorities state that the average life of such poles is about #ag years1 compared with #ad years for natural or untreated poles4 ,the application of pitch and tar oftentimes results in more harm than good4 ,it is authoritatively stated1 however1 that in ,europe wooden poles are effectively protected by painting them with tar up to about #b feet above1 and down to about #a feet below the soil line4 ,the painted parts of the pole are then covered with a cloth which after being nailed to the pole1 is also painted with tar4 ,finally a zinc plated sheet of iron painted on both sides with tar1 is placed around the cloth and tightened to the pole4 ,the saving due to the use of sterilized poles is #dj per cent4 of the cost of unsterilized poles4 ,the comparison is made on the following basis3 ,cost of pole1 #e each2 sterilizing1 #a4be2 renewal of sterilized pole in #bd years1 unsterilized pole1 in #ab years4 ,illustration3 ,,figs4 #icj to #icb4--,pole line construction tools4 ,fig4 #icj1 split wooden handle post hole auger2 fig4 #ica1 cant hook2 fig4 #icb4 socket peavey4 ,methods of ,setting ,wooden ,poles in ,unsuitable ,soil4--,in places where salt is plentiful and cheap1 such as the ,great ,salt ,lake region in ,utah1 it has been found that the liberal use of salt mixed with the dirt filling tamped in around the foot of the pole is very effectual in preventing decay below the soil line4 ,where poles have to be planted in low1 swampy ground1 or where the climatic conditions are such that timber decays rapidly1 it has been found advantageous to place the poles in concrete settings4 ,this method is extensively employed in various parts of the ,southern ,states1 square poles being placed in settings about #g feet deep and #c feet square4 ,in very soft ground the employment of a concrete setting is sometimes impracticable4 ,in such cases piles are driven deep into the soil1 and the pole bolted to the part of the pile extending above the ground4 ,reinforced ,concrete ,poles4--,the strongest point in favor of concrete poles is their durability4 ,untreated wooden telephone and telegraph poles have to be replaced by new poles about every six or seven years1 depending on the percentage of moisture in the soil1 the drier the soil1 the longer being the life of the pole4 ,concrete poles are not affected by soil conditions1 and if properly made will last indefinitely4 ,illustration3 ,,figs4 #icc to #ice4--;,glass insulator and insulator pin and bracket4 ,the insulator here shown is of the pony double petticoat type4 ,insulator pins are used with cross arms1 brackets are attached direct to the pole4 ,one form of reinforced concrete pole consists of a skeleton frame work of four corrugated iron rods covered with ordinary concrete4 ,the pole is octagonal in shape1 #cj feet long1 and provided with mortises for cross arms1 the latter being fastened in place by means of iron bolts4 ,it is stated that they are less expensive than pine poles1 and that each pole can be manufactured at the point on the line at which it is to be installed or planted4 ,in ,canada1 reinforced concrete poles are made square on account of the ease of making1 and also on account of the steel economy permitted thereby4 ,all poles are made at the point of erection4 ,they are moulded in wooden forms1 in a horizontal position1 the top side being left open and finished with a trowel4 ,the concrete is composed of one part of ,portland cement1 two parts clean sharp sand1 and four parts broken stone4 ,a #ce foot pole for ordinary line work weighs about #b tons and a #ej foot pole about #e tons4 ,cross ,arms4--,the familiar cross arms for stringing wires are usually attached to the poles before they are erected4 ,they are commonly made from yellow pine wood1 generally #c x #d inches1 and are freely coated with good mineral paint as a preservative4 ,attachment is made to the pole by cutting a gain one inch deep and of sufficient breadth to allow the longest side of the cross arm to fit accurately4 ,it is then secured in place by a lag screw1 with a square head1 so that it may be driven into place with a wrench4 ,illustration3 ,,fig4 #icf4--;,cross arm which carries the insulator pins4 ,the standard cross arm is #c x #d inches1 double painted1 and bored for #a inch pins and two inch bolt holes4 ,telephone arms are #b x #c inch1 bored for #a inch pins and two inch bolts4 ,the cross arm is further secured to the pole with braces4 ,these are flat strips of wrought iron or low carbon steel1 #cj inches long1 inch thick and #a inches wide1 according to standard specifications4 ,holes are bored at points one inch from either end1 one for attaching to the pole1 the other for attaching to the cross arm2 two braces forming a triangle with the cross arm for the base and with the apex at the point of connection to the pole4 ,like all other iron work used on pole lines1 the braces are carefully galvanized1 so as to stand three immersions of one minute each in a saturated solution of copper sulphate without showing copper deposits1 the color being black at the completion of the test4 ,before the cross arm is set in place the gain is carefully painted with white lead4 ,as it is important that cross arms on a line of poles1 particularly when there are several on each pole1 should be at equal distances from the ground as well as being uniformly spaced1 it is necessary that some measuring instrument should be used to accomplish this4 ,such an instrument is the ordinary template1 which is a length of board carrying a pointed block at one end1 to correspond exactly with the top of the pole1 and also cross cleats nailed at precisely the same intervals below it as it is proposed attaching the cross arms4 ,the template1 laid upon a pole1 shows where to cut the gains4 ,in planting the poles it is customary to so arrange them that the cross arms on alternate poles shall face in opposite directions1 for the purpose of equalizing the strain on the line4 ,on curves1 however1 all cross arms are placed on the side of the pole facing the middle of the curve4 ,ques4 ,what provision is made for attachment of the wires8 ,ans4 ,the cross arms are bored with holes for the insertion of the insulator pins1 which are made of locust wood and threaded at the upper end to receive the glass insulator4 ,the cross arm is made of such a length as to accommodate the number of pins to be inserted4 ,an arm for two pins is made three feet long1 according to the standard usually followed1 with holes for the pins at center points three inches from either end and a space of #bh inches between them in the center4 ,ques4 ,how must electric light and power wires be placed when wired on telephone or telegraph poles8 ,ans4 ,they must not be put on the same cross arm with the telegraph1 telephone1 or similar wires1 and when placed on the same pole with such wires the distance between the two inside pins of each cross arm must not be less than twenty-six inches4 ,illustration3 ,,fig4 #icg4--,portable platform with rigging as used by linemen in wiring and making repairs4 ,poles for ,light and ,power ,wires4--,in selecting the style of pole necessary for a certain class of work1 the conditions and circumstances should be considered4 ,poles may be divided into three classes1 the size of wire to be carried being one of the important considerations4 ,first ,class4--,main line of poles should range in length of from #cj to #ce feet with #f inch tops4 ,the height of trees1 of course will have to be considered in many cases4 ,second ,class4--,town lighting by arc lights4 ,all poles should have at least #f inch tops4 ,the corner poles should have #f inch tops1 and wherever the cross arms are placed on a pole at different angles1 the pole should have at least a #f inch top4 ,a #cj foot pole is sufficiently long for the main line1 but it would be advisable to place #ce foot poles on corners4 ,third ,class4--,where heavy wire1 such as ,no4 #jj1 is used for feeder wire1 the poles should have at least #g inch tops4 ,where mains are run on the same pole line the strain is somewhat lessened1 and poles of smaller size will answer4 ,cull ,poles4--,all poles that are smaller at the top than the sizes agreed upon1 are troubled with dry rot1 large knots and bumps1 have more than one bend1 or have a sweep of over twelve inches1 should certainly be classed as cull poles4 ,specifications for electric light and power work should be1 and in many cases are1 much more severe than those required by telegraph lines4 ,a cull pole1 one of good material1 is the best thing for a guy stub1 and is frequently used for this purpose4 ,a cedar pole is always preferable to any other1 owing to the fact that it is very light in comparison to other timber1 and is strong1 durable1 and very long lived4 ,pole ,setting4--,in erecting poles1 it seems to be the universal opinion of the best posted construction men that a pole should be set at least five feet in the ground1 and six inches additional for every five feet additional length above thirty-five feet2 also additional depths on corners4 ,wherever there is much moisture in the ground1 it is of much value to paint or smear the butt ends of the pole with pitch or tar1 allowing this to extend about two feet above the level of the ground4 ,this protects the pole from rot at the base4 ,the weakest part of the pole is just where it enters the ground4 ,never set poles further than #abe feet apart2 #aaj feet is good practice4 ,painting4--,when poles are to be painted1 a dark olive green color should be chosen1 in order that they may be as inconspicuous as possible4 ,one coat of paint should be applied before pole is set1 and one after pole is set4 ,tops should be pointed to shed water4 ,spacing the ,poles4--,in general1 the spacing of poles1 like their dimensions1 is regulated by the weight of the lines they are designed to carry--the heavier the lines the greater the number of poles4 ,the spacing of poles also depends on their liability to injury from storms and wind in any given locality1 and the nature of the service4 ,poles for a telephone line may be spaced twenty to fifty to the mile--that is1 from about #bfj to #ajj feet apart4 ,illustration3 ,,figs4 #ich to #ida4--,pole line construction tools4 ,fig4 #ich1 pike pole2 fig4 #ici1 raising fork2 fig4 #idj1 mule pole support2 fig4 #ida1 jenny pole support4 ,erecting the ,poles4--,since each pole on a properly constructed line is sawed to the right length and carefully shaped before it is finally inserted in the ground1 it is necessary that the holes be dug to as nearly the required depth as possible4 ,holes for poles are dug very little wider than their diameter at the butt1 and the depth is usually computed according to the nature of the soil and the weight of the proposed line4 ,excavation1 while sometimes accomplished with patent post hole augers1 or even dynamite1 is usually done with a long handled digging shovel1 and the earth removed with a spoon shovel1 such as is shown in fig4 #iba4 ,illustration3 ,,fig4 #idb4--;,guy anchor log in position4 ,illustration3 ,,fig4 #idc4--,stombaugh guy anchor4 ,it is made of cast iron and can be screwed into the ground like an auger4 ,wherever required by the nature of the soil1 a grouting or foundation of loose stones is formed in the bottom of the hole1 and1 in marshy or springy ground1 a base of concrete and cement is laid1 with filling of the same material around the pole1 when raised4 ,ques4 ,how are the poles transported to the holes8 ,ans4 ,they are rolled or carried on hooks similar to those used for carrying blocks of ice1 except for a long handle for lifting the load at either side4 ,illustration3 ,,fig4 #idd4--,method of raising a pole4 ,when the pole has been properly placed1 it is seized by several linemen4 ,as soon as the top of the pole is raised high enough to permit the pikes to be thrust into the pole1 it is then raised to a vertical position4 ,at about #ej the butt end slides into the hole4 ,the earth is then filled in around the pole and firmly tamped down4 ,eight or ten poles are about as many as can be set by the average gang in a day4 ,ques4 ,how are the poles raised and placed in the holes8 ,ans4 ,a piece of timber is inserted in the hole as a slide to prevent crumbling of the earth as the pole is slid into place4 ,the end is raised by hand sufficiently to allow the dead man1 or pole hoist1 to be placed beneath1 and this is moved along regularly as the pole is lifted with pike poles1 until it slides into place through the force of gravity4 ,illustration3 ,,fig4 #ide4--,method of pulling an anchor into place before the guy wire is fastened to the top of the pole1 thus obviating the liability of pulling the pole out of plumb4 ,this accomplished1 the pole is held in a perpendicular position by pikes in the hands of assistants1 or planted in the ground around it1 while the earth is carefully shoveled into the hole and thoroughly packed down with a tamper4 ,guys for ,poles4--,where poles are subject to severe strains which might throw them down and break the wires1 guy cables are largely employed1 these being attached near the top and secured either to the base of the next pole1 to a suitable guy stub or post1 or to a guy anchor1 which is buried about eight feet in the earth and held down by stones and concrete4 ,ques4 ,under what conditions is it necessary to guy poles8 ,ans4 ,they are guyed at corners in order to thoroughly secure the poles so that no strain may come on the cornerwise span4 ,it is also necessary to guy a line where it is to be deflected from a straight path1 as when rounding a hill1 water course or railway curve1 in order to neutralize the pull of the wires1 tending to incline the poles toward the center on which the arc is described2 also when descending a hill4 ,illustration3 ,,figs4 #idf to #idh4--,methods of guying corner poles4 ,the proper guying of corner and terminal poles is especially important2 on corners and curves1 the guys should be stronger and more frequent and should be placed on the outer side as shown in the diagrams4 ,illustration3 ,,fig4 #idi4--;,head and foot guying of a pole line in descending a hill4 ,guy ,stubs and ,anchor ,logs4--,in guying a line under such conditions1 each pole is connected by a suitable cable to a guy post or stub1 or to an anchor log4 ,standard rules specify stubs between #ah and #be feet1 with exact limits as to circumference measures at the top and at a point #f feet from the butt1 according to the kind of wood used4 ,illustration3 ,,figs4 #iej to #ieb4--,lineman's tools4 ,figs4 #iej and #iea1 ,eastern pole climbers1 with and without strap for attaching to legs2 fig4 #ieb1 portable vise with strap for pulling up the slack in splicing4 ,thus1 guy stubs of cedar or juniper1 either #ah or #be feet in length1 must have a circumference of #bb inches at the top and of #cb inches #f feet from the butt2 stubs of chestnut must measure #bd inches in the first1 and #cd in the second1 while those of cypress require #bh in the first1 and in the second1 #ci inches for an #ah foot length1 and at least #da for a #be foot length4 ,in planting guy stubs the same rules are followed as hold for poles1 every means being adopted to promote security of construction except that the stub is raked or tilted against the strain on the guy cable4 ,wiring the ,line4--,the erection and guying of the poles of a line as well as the attachment of the cross arms and the screwing on of the insulators are completed before the stringing of the line is begun4 ,it is particularly essential that the pull on poles of a given line be accurately calculated1 and that each one be guyed accordingly before the line is strung1 in order to avoid the danger of an undue strain upon the wires in attempting to rectify the condition afterward4 ,it is a good working rule that the wires should be subjected to no stress other than the weights of their own spans after they have been attached to the poles4 ,illustration3 ,,figs4 #iec and #ied4--,pay out reels4 ,fig4 #iec1 type used for telephone or telegraph work2 fig4 #ied1 type used for electric light work4 ,ques4 ,describe how the wires are strung4 ,ans4 ,in stringing the lines1 either one or the full number of wires may be put up at the same time4 ,when one line only is to be strung1 the operation consists simply in reeling the wire and running it off from a hand reel1 such as is shown in fig4 #iec or #ied4 ,at each pole the wire is drawn up to its place1 pulled out to the desired tension1 and attached to the insulator4 ,in the operation of stringing a number of lines at once1 the method is different4 ,the reels are placed at the beginning of a section1 each wire being inserted and secured through a separate hole in a board1 which is perforated to correspond with the spacing of the insulators on the cross arms4 ,a rope is then attached to this running board1 which is drawn by a team of horses through the stretch to be wired1 being lifted over each pole top in turn4 ,when a certain length has thus been drawn out the wires are drawn to the required tension between each pair of poles and secured to the insulators4 ,illustration3 ,,fig4 #iee4--,one form of come along4 ,the wire is inserted between jaws and is held fast when tension is applied to the ring4 ,illustration3 ,,fig4 #ief4--;,an improved form of come along or wire stretcher4 ,the jaws which grip the wire are smooth and remain parallel in closing1 thus the wire is not scratched or indented1 as with circular jaws having teeth4 ,ques4 ,how much tension must be put upon the wires8 ,ans4 ,in applying tension to the wires as they are strung on the poles1 it is the rule to allow some sag4 ,the amount of sag to be allowed varies with different line hangers4 ,a typical case quoted by one or two authorities gives a sag of four inches at the center of each #acj foot span for a given size of wire1 at a given temperature4 ,a more general rule is to make the tension on a wire as it is drawn up between each pair of poles equal to one-third of its breaking weight4 ,thus ,no4 #aj ,b4 ,s4 gauge1 would be drawn to about #afc pounds1 and ,no4 #ab to about #ajb pounds4 ,the temperature at the time of stringing and the distance between the poles are1 however1 important considerations in applying tension and allowing for sag4 ,thus1 one construction company specifies a dip of #aj inches in summer and #h inches in winter for spans of #acj feet1 or #dj poles to the mile4 ,several authorities specify figures about as given in the above table for ,no4 #ad iron or copper wire4 ,illustration3 ,,fig4 #ieg4--,wireman's come along with hook and tackle4 ,,sag ,,table ---------------------------------------- ----------------------------- ,temperature ,fahr4 ,span ---------------------------------------- ----------- in #cj #fj #hj ,feet ---------------------------------------- ----------- ,sag in ,inches ---------------------------------------- ----------------------- #ge #a #b #c ---------------------------------------- ----------------------- #ajj #c #d #e ---------------------------------------- ----------------------- #acj #e #g #h ---------------------------------------- ----------------------- #aej #f #i #aa ---------------------------------------- ----------------------- ,ques4 ,how is the wire drawn out8 ,ans4 ,in drawing out the wire1 it is customary to use a wire clamp1 or come along4 ,this tool is attached to a block and tackle1 or drawn in by hand1 and1 as soon as the proper force has been applied1 the wire is held1 while the lineman secures it to the insulator4 ,illustration3 ,,fig4 #ieh4--,lineman's block and fall with come alongs for stretching wire and holding same when making splices4 ,illustration3 ,,figs4 #iei and #ifj4--;,approved method of attaching wire to an insulator2 elevation and plan of insulator and tie4 ,the line wire is first laid in the groove of the insulator1 after which a short piece of the same size of wire is passed entirely around to hold it in place1 then it is twisted to the line at either side with pliers4 ,another contrivance for this purpose is the pole ratchet1 by which the wire is drawn tight and held until attached to the pole4 ,ques4 ,how are the wires attached to the insulators8 ,ans4 ,an approved method is shown in figs4 #iei and #ifj4 ,standard rules specify that all wires shall be tied to the side of the insulators toward the pole1 except on the insulators next to the pole1 where they are to be attached on the opposite side4 ,on curves1 however1 it is required that all wires shall be arranged so that the strain shall be against the insulator and not on the wire4 ,illustration3 ,,fig4 #ifa4--;,american wire joint4 ,this is a simple method of connecting the ends of the sections of wire by tightly twisting the ends around each other for a few turns2 it is the standard ,western ,union wire joint4 ,illustration3 ,,figs4 #ifb and #ifc4--,mc,intire sleeve and sleeve joint4 ,an approved method of making the joints of telephone lines is by the use of some form of sleeve1 such as is shown in fig4 #ifb4 ,this consists of two copper tubes of the required length1 and of sufficient inside diameter1 to admit the ends of the wires to be joined1 fitting tightly4 ,the tubes are then gripped with a tool1 shown in fig4 #ifd1 and twisted around one another1 so that the wires are securely joined and locked1 as shown in fig4 #ifc4 ,ques4 ,how are the wires spliced8 ,ans4 ,there are several methods of splicing wires4 ,fig4 #ifa shows the ,american wire joint1 and fig4 #ifc the ,mc,intire sleeve joint4 ,in making a joint1 the two ends are gripped by come alongs and drawn up to the proper tension with tackle as shown in fig4 #ieh4 ,the joint is then made as shown in the illustrations4 ,transpositions4--,in some classes of circuit1 as for instance telephone lines1 the current is often seriously affected by electrostatic induction from other lines1 and also from power circuits1 owing to the fact that the surfaces of the wires form1 as it were1 so many charging plates of an electrical condenser1 with the intervening air as the insulating layer or dielectric4 ,illustration3 ,,fig4 #ifd4--,mc,intyre's twisting clamp for wires #jj to #af ,b4 ,s4 gauge4 ,illustration3 ,,fig4 #ife--,method of making a transposition4 ,this is usually done by means of transposition insulators1 which are either double insulators1 one being screwed to the pin above the other1 or else such caps as are shown in fig4 #ifg4 ,such insulators are intended to act as circuit breakers1 the particular wire to be transposed being cut and dead ended1 or tied around1 on both the upper and lower grooves of the cap4 ,the free end of each length is then passed back and around the insulator and twisted1 or sleeve jointed to the other limb of its own circuit4 ,the telephonic current changes the pressure of its own charging surface as frequently as it alternates1 and this fact in itself is amply sufficient to account for a vast weakening of the current before it reaches its destination4 ,the only practicable method of overcoming this annoyance in pole lines is by the arrangement known as transposition1 which is1 briefly1 the practice of regularly shifting the relative position of the two limbs of each circuit as regards other wires in the same pole system1 as shown in fig4 #ife4 ,for short lines and pole systems with only a few wires it is not necessary to transpose very frequently4 ,on longer lines it has been found amply sufficient to transpose once every quarter mile2 that is to say to change the relative position of the wires of the different circuits at posts situated about that distance apart4 ,this does not mean1 however1 that each pair of wires is transposed so often1 but that on ordinary sized systems1 the transposition of some one circuit is amply sufficient to secure balanced relations and effectually counteract the effects of cross induction4 ,it is a matter which must be carefully calculated and planned in each particular instance in order to secure the best advantages4 ,illustration3 ,,fig4 #iff4--,telegraph and telephone line glass insulator4 ,illustration3 ,,fig4 #ifg4--,type of insulator used in making a transposition4 ,insulators4--,glass and porcelain are employed almost universally for supporting overhead wires4 ,insulators made of these materials are superior to those made of other material such as hard rubber1 or various compounds of vegetable or mineral matter1 with the exception perhaps of mica insulators used on the feeders of electric railway lines4 ,illustration3 ,,fig4 #ifh4--,tree insulator4 ,this type of insulator is especially useful in connection with temporary or repair work1 or where the wires pass through trees having numerous branches4 ,the illustration shows a ,cutler tree insulator lashed to the trunk of a tree4 ,it is made of a single piece of glass1 and is provided with a slot which the wire cannot leave accidentally4 ,the back of the device is concave and provided with ribs which prevent sliding4 ,it can be readily slipped over wires already in place1 is available for electric light circuit1 and will take wires up to inch1 in diameter4 ,illustration3 ,,figs4 #ifi and #igj4--,overhead cable construction4 ,in some cases1 particularly on short lines exposed to inductive disturbances from power and other electrical circuits1 it is usual to string the cables on poles such as usually carry the bare conducting wires4 ,it is not necessary1 however1 to insulate the cable in any way2 consequently it is merely hung to a supporting wire rope or cable1 called the messenger wire1 being attached either with some form of hanger1 such as is shown in figs4 #ifi and #igj1 or by loops of tarred marline4 ,the marline is sometimes wound over the cable and messenger wire from a bobbin1 but frequently it is merely wound on by hand4 ,cables used in such overhead construction consist of bundles of wires1 the pairs twisted together4 ,the size most often used is ,no4 #ai1 ,b4 ,s41 which is about 4#jcehi inch in diameter1 weighs #bj4g pounds1 and has a specific resistance of about #h ohms to the mile4 ,glass insulators are generally used on low tension lines1 and porcelain insulators on high tension lines1 the latter type being usually stronger and less brittle4 ,porcelain is more expensive than glass1 and its opacity prevents the detection of internal defects which would be readily observed through glass4 ,illustration3 ,,fig4 #iga4--;,clark's antihum2 a device designed to prevent the humming of telegraph wires4 ,ques4 ,what is a petticoat insulator8 ,ans4 ,an insulator which has one1 two or three deep flanges or petticoats around the base for the purpose of increasing the leakage path from the line to the pin4 ,both glass and porcelain insulators may be the double or triple petticoat type which may be cast or moulded solid1 or made in two or more parts which are subsequently cemented together4 ,service ,connections and ,loops4--,whenever it is necessary to tap an overhead conductor for service connection1 the method of connection will depend upon the character of the circuit4 ,in the case of a parallel circuit1 an extra insulator must be placed on the cross arm so as to prevent the service main putting a side strain on the main line conductor4 ,in the case of a series circuit the main line conductor is usually dead ended at the nearest pole and a loop taken to the point of service1 as shown in fig4 #igb4 ,illustration3 ,,fig4 #igb4--,method of making a series loop service connection4 ,illustration3 ,,fig4 #igc4--,parallel service connection4 ,service wires tapped to the main wires1 are run to insulators on an auxiliary cross arm1 thence to insulators on the side of the building1 and through the drain tube to the service switch4 ,illustration3 ,,fig4 #igd4--;,joint pole crossing1 showing wires of two lines crossing each other4 ,four guard wires 7shown heavier than the others7 extend for one span either side of the joint pole parallel to the wires of the lower circuits and protect them from contact in case of a break in the wires of the upper circuits4 ,these guard wires are insulated4 ,the minimum distance between high and low tension wires should be three feet4 ,five is better4 ,the end guards1 which prevent wires slipping off ends of cross arms and dropping on the lower wires1 should extend about six inches above the level of transmission line4 ,ques4 ,what are service wires8 ,ans4 ,wires which enter a building4 ,,chapter ,,xl ,,underground ,,wiring ,in large cities1 the best method of running wires for all varieties of electrical power transmission is to place them underground4 ,many city authorities have made this method of wiring compulsory by law1 because of the difficulty in approaching a burning building1 the danger from crossed and falling wires1 and the disfigurement of the streets where there is a network of overhead wires4 ,the expense of installing an underground system is very great in comparison with that of overhead construction1 but the cost of maintenance is much less and the liability of interruption of service greatly reduced4 ,underground ,systems4--,an underground system of electrical conductors is composed of three essential elements3 #a4 ,the conductor itself1 which is almost invariably of copper2 #b4 ,the insulation1 which is either in the form of a complete covering of insulating material1 or simply insulated supporting points2 #c4 ,the tube or conduit1 which constitutes the mechanical protection against the effects of the severe shocks1 weather conditions1 etc41 to which the system is naturally exposed4 ,the various underground systems may be divided into three classes3 #a4 ,lead encased cables laid directly in the ground2 #b4 ,solid or built in systems2 #c4 ,drawing in systems4 ,ques4 ,what may be said of the first mentioned construction8 ,ans4 ,where cables are laid directly in the ground1 the metallic covering1 consisting usually of a lead tube1 which is placed over the insulation is depended upon for mechanical protection4 ,such cables are largely used for short private lines and the first cost is less than that of the others1 but in case of repairs it has to be dug up4 ,ques4 ,describe the drawing in system4 ,ans4 ,in this construction the cables are drawn in after the conduits are built4 ,the conduit of the drawing in system may consist of various forms of pipe or troughs of iron1 earthenware1 concrete1 wood or fibre1 while those of the solid or built in systems are composed of either iron tubes or concrete trenches4 ,conduits4--,the principal qualifications of a good conduit are freedom from disintegration by the action of fire1 water1 acids1 alkalies1 or electrolysis2 second1 a smooth interior surface so as to permit of the easy drawing in of the cables2 and third1 a design which will permit of its economical installation in crowded streets4 ,there are numerous kinds of conduit of which may be mentioned3 #a4 ,vitrified clay pipe conduits2 #b4 ,vitrified clay or earthenware trough conduits2 #c4 ,concrete duct conduits2 #d4 ,wooden duct conduits2 #e4 ,wooden built in conduits2 #f4 ,wrought iron or steel pipe conduits2 #g4 ,cast iron pipe and trough conduits2 #h4 ,fibre conduits4 ,illustration3 ,,fig4 #ige4--;,a few forms of vitrified clay pipe conduits2 view showing single and multiplex types4 ,the dimensions of each duct are about #c #c4 ,the lengths vary from two to three feet4 ,vitrified ,clay ,pipe ,conduit4--,various forms of vitrified clay conduit appear to possess the qualifications1 desirable in underground construction1 to a higher degree than any other type4 ,they are made in both single and multiple duct1 as shown in fig4 #ige1 the single type being about #c inches in diameter1 or #c inches square1 and #ah inches long4 ,multiple conduit is made in two1 three1 four1 six and more sections1 ranging from #b to #c feet in length4 ,ques4 ,for what conditions is the single conduit especially adapted8 ,ans4 ,it is most suitable for use where the sub-surface conditions are characterized by a great crowding of gas1 water1 and other pipes1 as the conduits can be divided into several layers so as to cross over or under such pipes1 and many other sub-surface obstructions which are present in the streets of large cities and towns4 ,ques4 ,what are the features of the multiple duct conduit8 ,ans4 ,it can be laid somewhat cheaper than the single duct type1 especially in lines of about two to four ducts2 it is1 therefore1 most suitable for use in outlying communities where the streets are comparatively free from many sub-surface obstructions4 ,ques4 ,how is the conduit laid8 ,ans4 ,in laying conduit1 a trench is dug1 usually sufficiently wide to allow the placing of three inches of concrete on each side of the ducts1 and sufficiently deep to hold at least thirty inches of concrete on top of the upper layer of concrete forming the conduit1 and to allow for three inches of concrete in the bottom4 ,the trench is graded from some point near the middle of the block to the manhole at each intersection1 or from one manhole to the next manhole1 at a gradient not less than #b inches to #ajj feet4 ,ques4 ,how are single duct conduits laid8 ,ans4 ,the tiles of the several ducts are placed close together1 and the joints plastered and filled with cement mortar consisting of one part of ,portland cement to one part of sand4 ,when the conduit is being laid1 a wooden mandrel about four or five feet long1 three inches in diameter1 and carrying a leather or rubber washer from three to eight inches larger at one end is drawn through each duct so as to draw out any particles of foreign matter or cement which may have become lodged in the joints1 and also to insure good alignment of the tiles1 as shown in fig4 #igg4 ,single duct conduits are usually laid by bricklayers4 ,this fact accounts for the somewhat greater cost of the single over the multiple conduit which is usually laid by ordinary laborers4 ,one good brick-layer and helper1 however1 will lay from #bjj to #cjj feet of single duct conduit per hour4 ,practically the same standard of construction is maintained on all conduit lines from two ducts up to twenty-five ducts1 as many of the smaller lines may extend for miles into the outlying districts1 and contain transmission lines of the maximum working voltage4 ,illustration3 ,,fig4 #igf4--,vitrified clay or earthenware trough conduit2 this type of conduit consists of troughs either simple or with partitions1 the latter type being shown in the figure4 ,vitrified ,clay or ,earthenware ,trough ,conduit4--,it consists of troughs either simple or with partitions as shown in fig4 #igf4 ,they are usually made in tiles #c or #d inches square for each compartment1 with wall about one inch thick4 ,the length of the tiles ranges from two to four feet4 ,each of the two foot form duct troughs weighs about #he pounds4 ,when laid complete1 the top trough is covered with a sheet of mild steel1 about ,no4 #bb gauge1 made to fit over the sides so as to hold it in position1 and then covered over with concrete4 ,joints in ,multiple-duct ,vitrified ,clay ,conduit4--,in laying multiple duct earthenware conduit1 the ducts or sections are centered by means of dowel pins inserted in the holes at each joint1 which is then wrapped with a six inch strip of asphalted burlap1 or damp cheese cloth1 and coated with cement mortar as shown in fig4 #igh4 ,economy of space and labor constitutes the principal advantages derived from the use of multiple duct conduit4 ,illustration3 ,,fig4 #igg4--,method of laying single duct vitrified clay conduit4 ,the tiles of the several ducts are placed close together as shown in the figure1 and the joints plastered and filled with cement mortar consisting of one part ,portland cement and one part sand4 ,concrete ,duct ,conduits4--,these are usually constructed by placing collapsible mandrels of wood or metal in a trench where the ducts are desired and then filling the trench with concrete4 ,after the concrete has solidified1 the mandrels are taken out in pieces1 leaving continuous longitudinal holes which serve as ducts4 ,some builders produce a similar result by placing tubes of sheet iron or zinc in the concrete as it is being filled into the trench4 ,these tubes have just enough strength to withstand the pressure to which they are subjected1 and are1 therefore1 very thin and liable to be quickly destroyed by corrosion1 but the ducts formed by them will always remain unimpaired in the hardened mass of concrete4 ,wooden ,duct ,conduits4--,in this type of conduit1 the ducts are formed of wooden pipe1 troughing1 or boxes1 and constitute the simplest and cheapest form of conduit4 ,a pipe conduit consists of pieces of wood about #d inches square1 and three to six feet long1 with a round hole about three inches in diameter bored through them longitudinally4 ,as shown by fig4 #igi a cylindrical projection is turned on one end of each section1 which1 when the conduit is laid fits into a corresponding recess in one end of the next section4 ,the sections are usually laid in tiers1 those of one tier breaking joint with those of the tiers above or below4 ,illustration3 ,,fig4 #igh4--,method of laying multiple duct vitrified clay conduit4 ,the sections are centered by the dowel pins shown in the cut4 ,the trough conduit consists of ducts about #c inches square made of horizontal boards and vertical partitions1 usually of yellow pine about one inch in thickness4 ,this form of conduit can be laid in convenient lengths of #aj or #ab feet1 or it can be built along continuously4 ,ques4 ,what is the objection to the use of wood for conduits8 ,ans4 ,the decay of the wood tends to form acid which corrodes the lead sheath of the cable4 ,illustration3 ,,fig4 #igi4--,wooden pipe type of conduit4 ,it consists of pieces of wood about #d inches square1 and three to six feet long1 with a wide hole about three inches in diameter1 bored through them longitudinally4 ,ques4 ,how can this be prevented8 ,ans4 ,the decay of the wood can be prevented to a certain extent by the application of sterilizing processes1 thereby preserving it in fairly good condition for about ten to fifteen years4 ,ques4 ,for what service is wooden conduit best adapted8 ,ans4 ,for temporary installations which will be discontinued before the wood decays4 ,wooden ,built-in ,conduits4--,within recent years several forms of wooden built-in conduit have been designed and successfully used for permanent work4 ,they possess several advantages over any of the duct systems1 the chief of which are high insulating quality1 the capability of using bare wire and rods for underground conductors1 and reduced cost4 ,an approved form of wooden built-in conduit is shown in fig4 #ihj4 ,illustration3 ,,fig4 #ihj4--,perspective view of wooden built-in conduit4 ,it consists of an outer rectangular casing of wood which is lined inside with impregnated felt4 ,ques4 ,how are wooden built-in conduits installed8 ,ans4 ,a wooden trough is laid in a trench about #ah inches deep4 ,porcelain carriers as shown in figs4 #iha and #ihb are placed in the trough at intervals of #d to #e feet1 to act as bridgework for supporting the conductors4 ,this bridgework is placed on and is surrounded by impregnated felt or similar material1 and the spaces between the carriers1 after the conductors have been placed in position on them1 is filled with voltax1 which hardens rapidly and forms a solid insulating material throughout the conduit4 ,wrought ,iron or ,steel ,pipe ,conduits4--,these are formed of pipes similar to gas or steam pipes1 with screw or other connections4 ,they are laid either simply in the earth1 or in hydraulic cement1 and are the strongest and one of the most satisfactory forms of underground conduit4 ,an appropriate standard of this kind of work is shown in fig4 #ihc4 ,illustration3 ,,figs4 #iha and #ihb4--,porcelain bridgework or carriers for supporting underground conductors4 ,ques4 ,what is the ordinary method of construction8 ,ans4 ,a trench1 the width of which will depend upon the number of pipes to be laid1 is first dug in the ground1 and after its bottom has been carefully leveled1 is braced with side planking and filled to the depth of two to four inches with a layer of good concrete1 consisting of two parts of ,rosendale cement1 three parts of sand1 and five parts of broken stone capable of passing through a one and one-half inch mesh4 ,this concrete is well secured in place and forms the bed for the lowermost layer or tier of pipes4 ,ordinary wrought iron pipe is employed1 in #bj foot lengths about three to four inches in diameter1 depending upon the size and number of cables they are intended to carry4 ,after the last tier of pipes have been put in place1 and a layer of concrete from two to four inches placed over it1 a layer of two inch yellow pine planking is laid over the whole4 ,illustration3 ,,fig4 #ihc4--;,cross section of wrought iron pipe conduit laid in hydraulic cement4 ,the pipe connections consist of a taper screw thread coupling which can be easily made up as the pipes are laid1 and which forms a tight joint4 ,the pipes in each tier are usually laid from to of their diameter apart1 and when the first tier is in place1 the spaces between and around the pipes are filled in with concrete which is carried up over the pipes to a depth of about one-half a diameter to form the bed for another tier of pipes4 ,ques4 ,what is the principal object of the top covering of planks4 ,ans4 ,to protect the conduit against the tools of workmen making later excavations4 ,practical experience shows that workmen will dig through concrete without stopping to investigate as to the character of the obstruction1 but under similar circumstances1 will invariably turn away from wood4 ,ques4 ,how are the pipes treated before being laid8 ,ans4 ,they are dipped in tar to protect the outside surface from rust4 ,ques4 ,what is the most satisfactory form of lined iron pipe8 ,ans4 ,pipe lined with cement4 ,the internal surfaces of these pipes are usually covered with a lining of pure ,rosendale cement about inch thick and containing no sand4 ,the internal surface of the cement lining does not offer much friction to the introduction or withdrawal of the conductors4 ,these pipes are laid in cement or concrete in the same manner as plain iron pipe1 and are given a coating of tar on the outside to prevent rusting4 ,cast ,iron ,pipe and ,trough ,conduit4--,cast iron pipe for underground conduits is similar to ordinary wrought iron pipe1 except that it is thicker4 ,the additional thickness is necessary to make the strength equal to that of wrought iron2 it is therefore heavier to handle and more expensive4 ,ques4 ,describe a cast iron trough conduit4 ,ans4 ,it consists of shallow troughs of cast iron in six foot lengths1 laid directly in the earth so as to form a system of continuous troughing in which the conductors are placed and then covered over by cast iron covers which are bolted to the trough4 ,ques4 ,what advantages does this form of conduit possess over the duct type8 ,ans4 ,first1 the cables can be laid directly in place1 thus eliminating any chance of injury during the process of drawing in1 and second1 the cables are easily accessible at any point by simply removing one or two of the sectional cast iron covers1 thus permitting of their being readily inspected and repaired4 ,illustration3 ,,fig4 #ihd4--;,fibre conduit4 ,it consists of pipes made of wood pulp1 having about the same thickness as cast iron pipe4 ,slip joint conduit for electrical subways is three inches inside diameter4 ,the socket joints keep the lengths centered and make it easier to lay than a mere butt joint4 ,it is laid in cement like iron pipe4 ,branch connections can be made with greater facility than in the case of any duct system1 so that it is especially suitable for distribution systems were it not for the fact that it is so expensive as to be practically prohibitive4 ,fibre ,conduits4--,this form of conduit consists of pipes made of wood pulp impregnated with a bituminous preservative and insulating compound4 ,these pipes are laid in concrete in a manner similar to iron pipe4 ,fibre conduits are made in sizes ranging from #a inch to #d inches in diameter and from #b to #e feet in length1 with walls ranging from to inch in thickness4 ,ques4 ,name the three types of fibre conduit4 ,ans4 ,the socket joint type1 as shown in fig4 #ihd1 the sleeve type1 fig4 #ihe1 and the screw joint type1 fig4 #ihf4 ,ques4 ,what is the usual method of laying the socket joint type of fibre conduit8 ,ans4 ,after the trench has been dug to the required width and depth1 depending upon the number or pipes to be placed in a tier and the number of tiers1 a bed of concrete about #c inches deep is placed on the bottom and a line drawn on one side for the alignment of the first line of pipes4 ,the other lines of pipe or ducts are laid parallel to the first line1 and are separated from it and from each other by means of inch or inch wooden or iron pegs4 ,the pipes are well grouted and covered with a layer of concrete to the depth of or inch1 and the next tier laid in place in the same manner4 ,when the final tier of pipes has been installed1 it is covered with a layer of concrete about #b to #c inches deep4 ,illustration3 ,,fig4 #ihe4--,sleeve joint type of fibre4 ,both the socket type 7fig4 #ihd71 and the sleeve type here shown are easily aligned without the use of a mandrel4 ,ques4 ,what is done when it is necessary to cut a length of pipe to break joints1 or to enter a manhole8 ,ans4 ,the remaining part of the length may be utilized by using a fibre conduit sleeve having an inside diameter inch greater than the pipe being used on the system4 ,these sleeves are furnished by the manufacturers at a nominal charge per foot4 ,they are about four inches in length and fit over the ends of the abutting pipes1 so that they make tight joints and give perfect alignment4 ,although its employment is not permitted where fireproof regulations are in force1 fibre conduit is now being extensively used in other places1 and is giving satisfactory service4 ,it is not affected by moist earth and is impervious to the action of acids1 alkalies1 and gases4 ,as it is not subject to expansion and contraction1 leakage is practically eliminated1 and since it is a very good insulator1 troubles due to stray currents are reduced to a minimum4 ,it is extremely light1 comparatively non-breakable1 and can be accurately laid at the rate of #ab1jjj duct feet per day by a gang of common laborers1 consisting of two layers and three helpers4 ,illustration3 ,,fig4 #ihf4--,screw joint type of fibre conduit4 ,this method of connection will form a tight line and is suitable for running under the lawns of private houses and parks1 under the streets of towns and villages1 and in other places where the cost of building electric subways is prohibitive4 ,edison ,tube ,system4--,of the various built in or solid underground conduit systems other than those already described under wooden conduit systems1 the most satisfactory are the ,edison tube system1 the ,crompton naked conductor system1 the ,kennedy system1 which is a modification of the ,crompton and the ,callender systems4 ,ques4 ,describe the ,edison tube system4 ,ans4 ,it consists of a series of iron tubes or pipes containing one or more copper conductors which are placed therein before each complete section or pipe leaves the factory1 so that they only need to be joined together to form a continuous line of underground conduit with conductors in place4 ,the arrangement of wires and the details of the ,edison tube system are shown in figs4 #ihg to #ihi4 ,illustration3 ,,fig4 #ihg4--;,cross section of ,edison feeder tube4 ,this runs from the power station to the centers of distribution1 and contains two principal conductors and a smaller conductor to serve as a neutral wire1 and also three insulated cables of seven strands of ,no4 #ai ,b4 ,w4 ,g4 wire each4 ,these cables form independent circuits and enable the voltages at the distant end of the feeder to be read at the central station4 ,for this reason they are commonly called pressure wires4 ,underground ,cables4--,electric light and power cables for use in conduit may be divided into two classes3 moisture proof1 and non-moisture proof1 according to the character of the insulator4 ,in the moisture proof cables1 the insulation consists of some form of rubber1 or of bitumen1 and a metal sheath or covering1 usually of lead1 is provided to protect the cable from mechanical or chemical injuries4 ,the non-moisture proof cables are insulated with paper impregnated with oil1 wax1 or resinous compounds4 ,illustration3 ,,fig4 #ihh4--;,cross section of ,edison main tube4 ,a number of these tubes1 which radiate from the center of distribution and loop the ends of the feeders together1 have three conductors of the same size4 ,these tubes are placed in the ground so as to bring the positive and negative conductors on one side of the center of the tube1 and the neutral conductor on the other side4 ,the mains are always laid with the neutral conductor adjacent to the curb line1 and for convenience this side of the tube is commonly called the inside4 ,the feeders are always laid with the positive conductor on the right hand side1 as shown in fig4 #ihi4 ,metal ,sheaths on ,underground ,cables4--,metal sheaths are used on rubber covered cables to protect the insulating compounds from the deteriorating effects of electrolysis and various kinds of acids and gases which1 under present methods of construction1 are ever present in the underground conduits4 ,it is a fact1 however1 that the lead sheath on a low tension cable1 which is used as one side of a grounded circuit1 has been1 in some cases the cause of1 instead of1 cure for electrolysis4 ,the proper cure lies in the omission of the sheath altogether1 but as this is not practical except in the case of very large conductors1 the best thing that can be done is to interrupt the continuity of the sheath by some form of insulating joint4 ,illustration3 ,,fig4 #ihi4--,method of laying ,edison underground tube system4 ,the tubes are laid in trenches about #cj inches deep and #bj inches wide at the bottom1 each trench usually containing two lines of pipes--a main adjacent to the curb and a feeder on the outside4 ,the copper rods forming the conductors are uniformly #bj feet1 #d inches in length and project from #b to #c inches from each end of the pipes1 which are connected together by means of coupling boxes4 ,the coupling box usually employed consists of a two part egg shaped casting into which the ends of the pipes enter through water tight sleeves at the opposite ends of the oval4 ,the projecting ends of the copper conductors are joined by short pieces of flexible cable with sockets on each end1 which are drilled to fit easily over the conductor rods to which they are thoroughly soldered in order to make a perfect electrical joint4 ,after the conductors have been thus properly connected the cover is bolted down on the lower half1 and the whole of the interior of the box is filled with insulating compound through the small hole at the top of the cover1 thereby completely insulating the copper conductors1 the cable connectors1 and the ends of the tubes4 ,finally1 the hole in the cover is closed with a cast iron cap4 ,these coupling boxes are also made in the form of tees for making branch connections1 and in the form of elbows for turning corners1 the ball ends attached to the tubes and the sockets into which they fit being designed to permit of variation in direction through an arc of #ah degrees on either side of the central position4 ,services or branches to the consumers' premises consist of short lengths of tube which tap the mains by means of three way or four way service boxes1 the latter readily permitting the taking of two services from one joint4 ,services are never taken from the feeders1 but the latter are brought to distributing boxes containing three copper rings to which the conductors are connected and branched out to one or more mains which are led out through fuses to supply the districts4 ,pot ,heads4--,the upper end of a lateral cable is equipped with a discharge bell1 which is commonly called a pot head4 ,the purpose of a pot head is to hermetically seal the end of the cable and bring the conductors out in such a manner as to permit of their being conveniently connected to the primary service boxes4 ,illustration3 ,,fig4 #iij4--;,bottom of ,general ,electric manhole junction box2 view from manhole interior4 ,the cables enter the bottom of the box as shown through composition nozzles to which the lead sheathes are united by a wiped solder connection1 forming a permanent water and gas tight joint4 ,stuffing boxes are sometimes substituted1 doing away with the wiped joint1 rendering the boxes suitable for use with unleaded or braided cables4 ,the normal position of the distributing cables is in the upper ducts so that they may be brought to the junction box without crossing other lines4 ,the entrance nozzles and seats are so arranged that all terminals are soldered to cables outside of box and any cable may be removed without disturbing any soldered joint4 ,the wiped joints unite electrically the lead sheathes of all cables entering the box and by connecting a single earth bond to the shell of the box all cable sheathes are solidly grounded4 ,incombustible shields prevent the arc from a blown fuse making a ground connection to the shell or inner cover4 ,ques4 ,how are pot heads made8 ,ans4 ,they are usually made in three parts1 the base being of cast brass1 having a diameter depending upon the size of the conductors1 with a hole in the lower end threaded within in such a manner as to make a tight fit on the cable4 ,ques4 ,how is a pot head connected to a cable8 ,ans4 ,after the cable has been bent in to the proper position1 the brass base is slipped down over it with the larger end up1 and then screwed down on the lead sheath4 ,the threads cut down into the lead sheath to a distance of about inch along the sheath1 thus making an air tight connection without necessitating the making of a wiped joint4 ,the separate conductors are now bared of their insulation for a distance of about two inches1 and then spliced to heavy rubber covered braided wire of sufficient length to reach the primary service boxes4 ,the joints connecting these rubber covered wires and the cable conductors are spliced in the same manner as straight splices1 the paper sleeves used being of sufficient diameter to be backed out of the way over the rubber insulation4 ,when the splice is completed a brass shell threaded at one end to fit a female thread in the upper end of the brass base1 is slipped over the end of the rubber covered wire and screwed into the base4 ,a hood of sheet copper having the form of a quarter section of a ball is slipped over the top of the frame and its lower edge tracked in position below the horizontal shelf4 ,this hood makes the pot head water1 snow1 and insect proof4 ,,chapter ,,xli ,,wiring ,,of ,,buildings ,in laying out the circuits for a dwelling house1 the cut out cabinets should be located first4 ,in many houses only one cut out cabinet is necessary1 but in large houses it is convenient to have one on each floor1 with vertical mains running through them from the top to the bottom of the house4 ,if only one distributing point be used1 it should be either in the cellar or attic and risers run to the different floors4 ,ques4 ,how should the distributing centers or cut out cabinets be located8 ,ans4 ,they should be installed near a partition that is so located as to make the running of risers easy1 and should be on an inside wall to guard against dampness4 ,ques4 ,what instructions are usually given the electrician who does the wiring8 ,ans4 ,in many cases simply a plan showing the location and number of lights1 from which he must figure out how to install them using the least amount of material and labor consistent with a good installation that will pass inspection4 ,ques4 ,what provision should be made in rooms where lamps are suspended from the ceiling8 ,ans4 ,a switch should be placed at a point where it will be convenient for any one entering to turn on the light4 ,ques4 ,where are receptacles usually placed8 ,ans4 ,in the baseboard4 ,a receptacle is a convenient device which permits any one to connect a lamp to the electric lighting system by inserting a plug which is connected by flexible cord to the lamp4 ,illustration3 ,,fig4 #iia4--;,ceiling button4 ,if a lamp be needed not more than #c feet from the direct line of the wires1 it can be hung where required by means of a ceiling button1 as shown in the figure1 but the lamp cord must not be used to run lamps in this way more than two or three feet from the rosette4 ,ques4 ,what provision should be made in wiring a hallway8 ,ans4 ,the switching arrangement should be so designed that the lights may be turned on or off either from the hall or floor above4 ,ques4 ,what is this arrangement called8 ,ans4 ,a two way switch1 as shown in fig4 #iib4 ,ques4 ,how can a two way switch be distinguished8 ,ans4 ,it has three binding screws1 two on one end and one on the other4 ,illustration3 ,,fig4 #iib4--,two way lighting circuit permitting control from two points4 ,this is the usual arrangement for hall when it is desired that the lights may be turned on or off from either floor4 ,the circuit contains two two way switches connected by travellers4 ,from the diagram it is seen that the light may be controlled from either switch4 ,it is a bad arrangement to have travellers and return wire located near each other1 as it is possible by this method to connect two individual circuits together and possibly overload one of the two feed wires of each circuit4 ,however1 should each feed wire run to a fuse direct1 without any other lamps than those contained in the three way circuit being connected1 it is not objectionable and becomes a convenient method in many cases4 ,illustration3 ,,fig4 #iic4--;,four way lighting circuit1 permitting control from three points4 ,this arrangement consists of a four way switch connected between two two way switches as shown4 ,in making the connections it should be noted that the travellers connecting one side of the four way switch to the two way switches should be crossed4 ,on the opposite side of the four way switch1 the connections are direct4 ,for the various positions of the switches1 the corresponding circuits through them are as follows3 ,,abdghj--,,abdeij--,,acfghj--,,acfeij4 ,ques4 ,how may a group of lights be controlled from three points8 ,ans4 ,by the use of a #d way switch and two #b way switches connected as shown in fig4 #iic4 ,ques4 ,before laying out the wiring system for a building1 what should be done8 ,ans4 ,it is necessary to ascertain whether power will be supplied from the central station1 or whether a private plant is to be installed4 ,illustration3 ,,fig4 #iid4--,two wire multiple system as used with isolated plant4 ,ques4 ,what wiring system should be used with a private or isolated plant8 ,ans4 ,the two wire multiple system as shown in fig4 #iid4 ,ques4 ,when the central station is to supply power as an auxiliary in case of break down1 how should the connection be made8 ,ans4 ,the supply from the central station should be connected to the wiring system through a double throw switch1 as in fig4 #iie1 so that either source may be thrown into circuit4 ,ques4 ,how are the connections made when the auxiliary supply is brought in through a three wire system8 ,ans4 ,a double throw three pole switch is used as shown in fig4 #iie4 ,illustration3 ,,fig4 #iie4--;,double throw switch for use in isolated plants when auxiliary power is used from the central station in case of breakdown4 ,ques4 ,when power from an outside source only is to be used what must be determined before wiring8 ,ans4 ,the system of wiring of the supply4 ,if a three wire system be used1 the general arrangement will be as shown in fig4 #iig4 ,illustration3 ,,fig4 #iif4--;,double throw three pole switch for use in isolated plants where auxiliary power is brought in through three wire system4 ,the side of the switch controlling the current is bridged as shown4 ,ques4 ,would it be expensive to change a regular three wire system to a two wire system8 ,ans4 ,it would require the reinforcement of all mains and feeders by an additional wire4 ,this wire would be connected with the neutral wire so as to make the capacity of the neutral equal to the sum of the other two4 ,if a three wire two wire system had been originally installed1 no change in the wiring system would be necessary4 ,the only change would be at the service end of the switchboard1 and the doubling of the size of the center fuses4 ,illustration3 ,,fig4 #iig4--,three wire convertible1 or three wire two wire system2 used to advantage where power is supplied from an outside source and brought in through the three wire system4 ,the only difference between the three wire convertible1 and the straight three wire system is that the center1 or neutral1 wire of the mains and feeders should have a current capacity equal to the other two4 ,the reason for this is that it allows the system to be readily changed over to a two wire system for use in connection with a private plant4 ,it sometimes happens that after using power from the local electric illuminating company for some time1 conditions arise which make it expedient for the owners to install a private electric plant4 ,if a straight three wire system had been originally installed1 the mains and the feeders when used on a two wire system would not be heavy enough by #be per cent41 as the neutral wire of a straight three wire system is the same in size as one of the two outer wires1 and theoretically carries one-half the current or less4 ,ques4 ,is a three wire system desirable with an isolated plant8 ,ans4 ,it is more expensive to install than one for a two wire system1 as it is necessary to add a balancer in connection with a #bdj volt dynamo4 ,this balancer set should have one-tenth the capacity of the plant4 ,such an equipment has its advantages when #bdj volt motors and #abj volt lamps are connected to the system4 ,with this plant no changes in the motors are necessary1 whereas in a straight #abj volt system1 the motors would have to be changed from #bdj to #abj volt machines4 ,illustration3 ,,fig4 #iih4--;,diagram showing reinforcement of neutral wire necessary to change regular three wire system to two wire system4 ,the capacity of the neutral wire must equal that of the sum of the two other wires4 ,ques4 ,after deciding on the system of wiring to be used1 how should the electrician proceed with the work8 ,ans4 ,he should lay out the mains1 feeders and branches of the wiring system4 ,the outlets are first located and then the distributing centers4 ,there is no fixed rule or plan by which to go1 but the current density and source of supply are the main points to be considered in locating these centers4 ,he must also consider the construction of the building and select runways and shafts which provide easy runs for feeders4 ,ques4 ,how should panel boards be placed8 ,ans4 ,panel boards in loft buildings or in any building requiring #h to #aj circuits to a floor should be distributed one to a floor4 ,in private houses it is sometimes advisable to install only one panel for the entire house4 ,this is good practice for a three-story house not requiring over twelve circuits4 ,illustration3 ,,fig4 #iii4--;,diagram showing current required on each floor of building4 ,a sketch of this kind is useful in laying out the feeder system4 ,in the building here shown it will be seen that the basement and first floor require the most power4 ,in such a case a feeder is run for these floors1 and a sub-feeder from the basement to the first floor4 ,it is not worth while to reduce the size of the sub-feeder unless the amount of current used on the sub-feeder be a small percentage of that used in the feeder4 ,another reason is that in changing the size of a wire1 the underwriters require a fuse to be inserted4 ,this makes it necessary to install a larger panel with larger trim1 etc41 and the consequent expense easily offsets any gain made by installing a smaller wire4 ,in a building covering a large area it is often advisable to install two panels or centers to a floor1 with two sets of feeders4 ,it is advisable to keep circuit lengths down to #ajj feet or less1 and the judicious laying out of circuit centers will save many feet of wiring4 ,ques4 ,how should the arrangement of feeders for a large building be determined8 ,ans4 ,a good method is to draw an elevation of the building as in fig4 #iii1 and note on each floor the current requirements4 ,the best plan is to furnish a feeder for every floor1 especially in large installations4 ,in smaller installations one or two feeders are sometimes all that are required4 ,illustration3 ,,fig4 #a1jjj4--;,diagram showing arrangement of switches in wiring system where provision is made that any circuit can be fed from an outside source in case of overload or accident4 ,ques4 ,how should feeders for motors be installed8 ,ans4 ,they should be independent of the lighting feeders4 ,ques4 ,what is the largest size of feeder that should be used8 ,ans4 ,feeders requiring over #b inch pipe should not be used4 ,it is better to subdivide them1 especially if there be many bends or offsets1 since two inch pipe is about the limiting size for economical handling4 ,ques4 ,how should feeders be arranged8 ,ans4 ,they should radiate from a distributing panel1 having a proper sized switch and fuse for each feeder4 ,if the system of wiring be such that auxiliary power is taken from a local lighting company1 it is a good plan to have each circuit controlled by a double throw switch so that in case of overload any circuit can be fed from the illuminating company's mains as in fig4 #a1jjj4 ,illustration3 ,,fig4 #a1jja4--,sectional view showing method of cutting a pocket or opening in floor for the insertion of wires4 ,ques4 ,how should feeders and mains be run8 ,ans4 ,it is advisable to install them in iron pipe even though the circuit wires be run otherwise4 ,since the former carry the main supply of current it is important to have them well protected as they usually run up side walls4 ,the underwriters make numerous restrictions against open or moulding work on brick walls and require good protection1 and this is an additional reason for piping the mains and feeders4 ,ques4 ,how much load should be placed on the branch circuits8 ,ans4 ,in laying out the branch circuits1 it is not good practice to use up the underwriters' circuit allowance of #ffj watts4 ,illustration3 ,,fig4 #a1jjb4--,view of outlet pocket showing base board1 and cover supports in position4 ,if a circuit be wired with the full allowance of lamps1 no additions could be made without violating the underwriter's requirements4 ,ques4 ,if concealed wiring is to be installed in a finished building what should be done first8 ,ans4 ,the outlets should be marked on the ceilings and walls with a pencil cross at the spot1 marking also the location of switches1 etc4 ,ques4 ,if an outlet is to be placed at the center of a room1 how is the center of the ceiling located8 ,ans4 ,it is first located on the floor1 then transferred to the ceiling by means of a plumb bob4 ,ques4 ,what is the first operation in making a ceiling outlet8 ,ans4 ,a small hole is bored through the ceiling and the bit pushed up till it comes in contact with the flooring of the room above1 this flooring is also bored1 as in fig4 #a1jja4 ,illustration3 ,,fig4 #a1jjc4--,view of completed pocket and ceiling outlet showing method of bringing out the wires4 ,a long bit about inch in diameter and about #ah inches long is used4 ,the hole bored in the floor above will show where to take up the board to install the wires4 ,ques4 ,how is a pocket opened above the hole bored for ceiling outlet8 ,ans4 ,one-quarter inch holes are bored to insert a keyhole saw through the joint between two boards at each end of the pocket1 and as near the beams as possible1 then the board is cut at an angle as indicated in fig4 #a1jja4 ,having sawed across the board at both ends1 it is pried out with a chisel as shown4 ,ques4 ,how are the holes bored through the beams for the tubes8 ,ans4 ,they are bored about two inches from the top with a #i_/af inch bit1 slanting downward just enough to give clearance for the brace4 ,illustration3 ,,fig4 #a1jjd4--;,device for examining partition interiors4 ,a pocket flash lamp and a little mirror are the only apparatus required to inspect the interior of a wall or partition which would ordinarily be inaccessible4 ,for fishing wires1 retrieving cable and inspecting finished work1 the lamp and mirror will be found most useful4 ,the mirror has only to be introduced in the outlet hole in the wall1 the flash lamp and eye being held behind it as illustrated4 ,the mirror reflects the light of the lamp onto the place to be illuminated1 at the same time reflecting the image back to the eye near the lamp4 ,the usefulness of this little device is as great as its simplicity4 ,ques4 ,how are the knobs fastened8 ,ans4 ,screws may be used but stout wire nails are satisfactory and are inserted with less labor4 ,leather nail heads are slipped on the nails to protect the porcelain4 ,ques4 ,how is a ceiling outlet completed after the work has reached the stage shown in fig4 #a1jjb8 ,ans4 ,a baseboard is next installed as in fig4 #a1jjc to have a secure hold for the screws used in fastening the fixtures4 ,two holes are then bored diagonally with a #aa_/af inch bit inserting the bit in the small hole bored in the ceiling as in fig4 #a1jja4 ,the outlet wires are then tied around the knobs and the upper ends being bared and tapped on to the main wire4 ,a piece of loom is slipped on each outlet wire after which it is thrust through the outlet as in fig4 #a1jjc4 ,illustration3 ,,fig4 #a1jje4--,plan showing one floor of a dwelling house wired with conduits4 ,the numbers on the various outlets indicate the number of lamps supplied4 ,the wiring is carried out on the loop system1 and it will be noticed that no branches are taken off between outlets4 ,four circuits are used in order that there may not be more than ten lamps on any one circuit4 ,ques4 ,how are the mains secured to the knobs8 ,ans4 ,by taking a turn around the intermediate knobs and a dead end hitch at the end knobs1 or they may be hitched at each knob4 ,the main may be secured also by use of a tie wire4 ,ques4 ,what is the difference between a splice and a tap8 ,ans4 ,a splice is the joining of two wires at their ends2 a tap is the joining of the end of one wire with an intermediate point of another wire4 ,illustration3 ,,fig4 #a1jjf4--,wiring for heating appliances in two story house2 plan of basement4 ,ques4 ,what precaution should be taken in making joints8 ,ans4 ,all wires joined together should be soldered as this insures good electrical contact4 ,unsoldered wires are both unreliable and dangerous1 since they will corrode from dampness1 thus increasing the resistance of the joint so that it may become heated4 ,ques4 ,how should joints be finished after soldering8 ,ans4 ,they should be covered with rubber tape twisted tightly while it is hot4 ,when the rubber has melted it will adhere to the joint and can be moulded with the fingers4 ,adhesive tape is then wound over the rubber1 the insulation thus being made equal to that which was removed to unite the wires4 ,illustration3 ,,fig4 #a1jjg4--,wiring for heating appliances2 plan of first floor4 ,wiring for ,heating ,appliances4--,there are now on the market a great number of heating appliances which absorb such small amounts of energy that they can be used readily on the lighting circuit4 ,these appliances include the coffee percolator1 chafing dish1 heating pad1 small water heater1 cigar lighter and many other miscellaneous devices4 ,by adapting these smaller devices to the lighting circuit1 not only is the cost of wiring decreased1 but the convenience and cleanliness of the electrical system is secured4 ,illustration3 ,,fig4 #a1jjh4--,wiring for heating appliances2 plan of second floor4 ,the location of the outlets for the heating appliances is not of the least importance4 ,for many purposes1 the flush receptacle in the baseboard of the room answers many requirements4 ,in other places1 for instance1 a receptacle placed beneath the bracket lamp in the bathroom upon the same circuit as the lamp1 is very convenient as a connection for the electric shaving mug or the massage motor4 ,similarly1 a suitable outlet placed near the head of the bed is most convenient for operating a heating pad as it does not necessitate unscrewing a lamp at night4 ,the house illustrated in figs4 #a1jjf to #a1jjh is an example of the use of a single electric heating circuit with a restricted use of the lighting circuit for heating purposes4 ,illustration3 ,,fig4 #a1jji4--;,diagram illustrating wiring with combination of moulding1 flexible tubing or conduit in non-fireproof building1 where wiring had not been originally installed4 ,in such cases the moulding may be run in a cornice in the hall4 ,when objectionable to have the work exposed in the rooms1 taps may be made in the moulding opposite each room and the circuit extensions from the moulding to the center outlets in the rooms may be run in flexible conduit1 fishing the wires from the moulding to the ceiling outlet4 ,the use of wooden moulding in new buildings is not to be recommended for the reason that it is not usually fireproof1 and it would be better to run the conductors concealed in some form of conduit2 if the circuit work were installed at the time the building is erected1 it would cost but little more than moulding1 and would be much more substantial4 ,in some cases1 however1 wooden moulding might be provided in a new building on the ceiling as a means of affording facilities for making connections to outlets over desks1 tables1 etc41 where it would be impossible to locate the outlet exactly before the building was plastered4 ,in such cases1 the moulding could be installed on the ceiling at a distance of #ah to #bd inches from the walls1 forming a rectangle on the ceiling4 ,illustration3 ,,fig4 #a1jaj4--;,feeder system for large hotel4 ,the cellar1 basement1 and ground floors are supplied by separate feeders1 because of the importance of having continuous and uninterrupted lighting service at these floors4 ,the three distributing centers at the cellar are supplied by a single feeder4 ,three of the eight distributing centers at the basement floor serve to supply the outside lights1 as described above4 ,the distributing center for the outside street lamps is supplied by a separate feeder from the main switchboard4 ,five of the distributing centers at the basement floor serve for the basement lights only2 they are fed by two separate feeders1 one of which serves two centers and the other three centers as shown4 ,each of the three centers at the ground floor is supplied by a separate feeder4 ,the upper floors1 from the first to the fourteenth inclusive1 are divided into two symmetrical sections4 ,each section has its own distributing center1 and its own set of supply feeders4 ,the feeder terminates at the middle center of a group of three1 and is extended by mains to the corresponding centers at the floors immediately above and below4 ,each feeder from the first to the twelfth floor inclusive serves to supply three distributing centers4 ,as can be seen in the basement plan1 the main supply circuit enters the basement and from this the heating circuit and lighting circuits branch1 as shown by the arrows4 ,the heating circuit runs direct to the basement laundry1 a branch running to the flat iron4 ,connections are made with the kitchen on the first floor and with the dining room by branch circuits running through the partitions to the respective rooms4 ,the heating circuit at the dining room is provided with flush wall receptacles1 to which connection is made for the chafing dish and percolator4 ,in the kitchen the electric baking outfit is arranged as shown4 ,this electric outfit is used for auxiliary cooking1 such as a gas range would be1 and the oven1 placed by itself on the opposite side of the coal range1 is controlled from the main table4 ,upstairs the heating circuit1 upon which the dining room appliances are operated1 is extended to supply current to the electric luminous radiator1 either in the chamber or bathroom4 ,the arrangements for the lighting circuits are shown in the figures4 ,landing and basement lights are controlled by three way switches to make them convenient4 ,in the living room a flush floor receptacle is installed so that the reading lamp1 chafing dish or coffee percolator can be operated without necessitating the use of a long cord4 ,a few of the electrical outlets suitable for the purposes mentioned are illustrated4 ,where several heating circuits are used it is essential that an appliance taking a large current be not placed on the regular lighting circuit4 ,to guard against this possibility1 special receptacles should be installed1 constructed for plugs which will not fit any other receptacle4 ,,chapter ,,xlii ,,sign ,,flashers ,the devices used for giving the flashing and changeable effects to electric lights in any form are called flashers4 ,the mechanism may be constructed to flash a sign by spelling the words out1 one letter at a time1 flashing border lights around a window1 changing colors in glass signs1 or in fact in any way to attract the eye4 ,there are two advantages in favor of using a flasher3 #a1 it causes the passerby to look at the sign1 and #b1 reduces the cost of electricity1 because the lamps are switched off periodically4 ,there are numerous kinds of flasher1 and they may be classified1 according to construction of the switch contacts1 as3 #a4 ,carbon type2 #b4 ,brush type2 #c4 ,knife type4 ,again1 with respect to operation or the electrical effects1 they may be classified as #a4 ,simple on and off flashers2 #b4 ,high speed flashers2 #c4 ,lightning flashers2 #d4 ,script breakers2 #e4 ,chaser flashers2 #f4 ,thermo flashers2 #g4 ,carriage calls2 #h4 ,talking signs2 #i4 ,electric clocks4 ,illustration3 ,,fig4 #a1jaa--;,dull's carbon type flasher4 ,this is a main line flasher2 that is1 it is set into the main wires instead of carrying down each circuit4 ,the circuits are opened and closed on carbon contacts1 reinforced with standard knife switches4 ,the blades are opened and the current broken by gravity alone4 ,each switch can be made to hold the lights for any period from #ah to #ha of a revolution of the shaft4 ,they can throw on the circuits progressively or all on and all off together4 ,again1 the circuits may be closed progressively1 remain on a few seconds1 and then be opened progressively4 ,no circuit or circuits can be closed more than once per revolution4 ,carbon ,flashers4--,in this type of flasher1 carbon breaks are provided1 that is1 the arc which is formed when the circuit is broken1 falls on carbon1 while metal switches are provided to carry the load4 ,thus the carbon gets the arc which prevents the switches burning1 while the switches carry the load to prevent the carbons becoming heated and disintegrated4 ,the carbons must be adjusted occasionally according to the load they are carrying4 ,carbon machines are made either double1 triple1 or series break4 ,illustration3 ,,figs4 #a1jab to #a1jad4--,wiring diagrams for ,dull's carbon flashers4 ,fig4 #a1jab1 usual method of wiring4 ,the load is balanced by running the neutral wire around the machine1 to the cut outs1 breaking the outside legs only of a #bbj-aaj volt system4 ,while this method of wiring is entirely feasible1 it is no harder on the contacts1 and permits the use of a cheaper machine1 but it is technically a violation of the underwriters' rules1 which say that all circuits of more than #ffj watts must be broken double pole4 ,if the load be balanced there would be double pole break at #bbj volts1 and the lamps would be in series1 but if the load be not exactly balanced1 there would be single breaking to the extent of the amperes over the average balance4 ,in other words1 it is a double break and it is not according to circumstances1 and the use of this machine wired as above is a matter that should be taken up with the local inspector before installing4 ,fig4 #a1jac1 diagram for connecting a straight two wire carbon flasher on a two wire system4 ,fig4 #a1jad1 diagram for connecting a straight three wire carbon flasher on a three wire system and breaking the neutral4 ,illustration3 ,,fig4 #a1jae4--,reynolds' brush type flasher4 ,the brush type1 as its name indicates1 is of brush construction and is limited to #e amperes capacity on each switch4 ,the cams constituting a drum are of heavy construction while the brushes are of fine copper several leaves thick4 ,it is most commonly used for spelling signs1 that is1 for letter by letter flashing4 ,illustration3 ,,fig4 #a1jaf4--,reynolds' knife type of flasher with metal contacts4 ,the construction is cheaper than the carbon type4 ,it is mounted on a slate base1 and is heavily built throughout4 ,the switches are designed for #ae amperes capacity double break4 ,brush ,flashers4--,these machines are provided with brush contacts4 ,these bear on cams constituting a drum1 and they are usually made of several strips of copper4 ,brush flashers are generally used for spelling out signs one letter at a time1 or work of a similar nature4 ,illustration3 ,,fig4 #a1jag--,sign flasher transmission gearing4 ,the view shows an oil tight gear case with cover plate removed4 ,the gears are equipped with ball bearings and run in graphite grease4 ,by means of the worm gear the large speed reduction necessary between the flasher shaft and motor is obtained without a multiplicity of gear wheels4 ,knife ,flashers4--,this type of construction is cheaper than the carbon type4 ,the switches are of the knife type with metal contacts4 ,one manufacturer states that it is not advisable to build knife flashers for more than #ae amperes per double pole switch1 as they cannot be depended upon to break a greater load for any length of time4 ,simple ,on and ,off ,flashers4--,these are used for flashing whole signs or heavy loads on and off4 ,a flasher of this type consists essentially of a revolving double pole switch with reducing gear and connection to a small motor for operating same4 ,illustration3 ,,fig4 #a1jah4--,simple on and off double pole flasher for all on or all off sign flashing4 ,the machine is furnished with any number of switches ranging from #e amperes up4 ,the machine may have only one switch or any number of switches4 ,the connection to motor may be by belt or chain1 or the motor may be directly connected to the worm gear4 99 99 99 99 99 ,flash ,system of ,gas ,lighting--,this system for simultaneously lighting a large number of gas burners1 is used in large halls1 churches1 theatres1 etc4 ,two sparking points1 each insulated one from the other and from the burner1 are arranged at each burner1 so that a spark between the points passes through the jet of gas and ignites it4 ,a number of sparking points and the secondary of an induction coil are connected in series4 ,when the circuit through the primary of the induction coil is closed1 sufficient pressure is induced in the secondary to cause sparks to jump across every jet in the series4 ,since the voltage is high1 the wires must be installed with great precaution4 ,the wire should be enclosed in glass tubing wherever it comes within less than #a in4 from the gas piping1 except where purposely grounded4 ,high ,speed ,flashers4--,machines of this type are used for giving what is generally known as high speed effects1 such as fountains1 water1 steam1 smoke and fire effects1 whirling borders1 revolving wheels and work of a similar nature4 ,illustration3 ,,fig4 #a1jai4--;,dull's high speed flasher4 ,it is mounted on a slate base #ab inches wide1 the length being governed by the size of the machine4 ,motion is given to the rotary switches through worm and belt gearing4 ,iron cams are used1 the current being taken therefrom by six-leaf brushes1 provided with stiffeners4 ,the wiring for the machine is simple2 #d c4p4 lamps can be run on one wire4 ,a border or ornament containing #afj lamps requires #ab wires between the sign and flasher4 ,the flasher is made in #d switch sizes only1 viz43 ,no4 #d1 #h1 #ab1 #af1 etc4 ,this is due to the fact that there are three parts of light to one of darkness4 ,lightning ,flashers4--,these machines are for giving the appearance of a streak of lightning going across a display4 ,there is very little expense attached to their operation1 because not more than two-thirds of the lamps are turned on at one time1 and this number for only about one-sixth of the time1 as compared with the sign burning steadily4 ,lightning strokes can be utilized in various ways1 either alone or with other advertising pieces4 ,alone they can be placed along a cornice1 across the front of a building1 up and down the corners leading to a doorway1 etc4 ,they can be used in the center of a sign with letters above and below4 ,in this case1 it is best to alternate the stroke with the letters1 that is1 flash the wording on and then off4 ,as soon as it goes out1 the stroke flies across in the darkness1 then the wording comes up again1 say six times a minute4 ,illustration3 ,,fig4 #a1jbj--,wiring diagram for flags4 ,these may be wired for high speed flashers by gradually increasing the lamp centers between the vertical rows from the flag staff to the end4 ,illustration3 ,,fig4 #a1jba4--;,diagram showing method of wiring for high speed effects on single lines4 ,this wiring diagram would be carried out the same in the case of a travelling border1 whether it be straight or otherwise4 ,in the case of a fountain1 begin numbering each stream at the bottom and carry out the same scheme to the end of that stream4 ,when several streams are parallel1 all the lamps may be connected in a row the same as though they were an individual lamp4 ,care should be taken not to get more than twenty ,no4 #a lamps on a circuit4 ,among the effects that may be obtained are a revolving wheel1 a column of flame1 and a straight travelling border with part of the ,no4 #a lamps from each effect to the same ,no4 #a wire1 carry it back to any ,no4 #a switch on the machine1 and the effect will come out right4 ,for instance1 in a flame effect with sixteen ,no4 #a lamps1 four ,no4 #a lamps could be taken in the straight border1 and put on the same wire1 and the effect would come out right4 ,the spacings for high speed effects vary1 according to the size of the sign4 ,travelling borders around an ordinary sign #c x #aj feet should have their lamps spaced about six inches apart4 ,in a fountain fifteen feet high1 the lamps should be spaced about nine inches apart4 ,illustration3 ,,fig4 #a4jbb4--,method of wiring for a torch4 ,this wiring diagram gives the correct method of wiring smoke1 flames1 steam1 and water effects4 ,it may be the flame in the top of a torch as here shown1 liquid pouring out of a bottle1 smoke rising from a cigar1 or dust behind an automobile wheel4 ,the only difference being in the direction each goes and the outline of the bank of lamps4 ,wire the lamps in unequal lines across2 avoid any straight lines because it gives a mechanical effect which is not natural4 ,if the effect be to rise1 mark the lower row ,no4 #a1 the next row above ,no4 #b1 etc4 ,pick up all the ,no4 #a rows until there are twenty lamps1 and attach them to ,no4 #a wire which will go back to any ,no4 #a switch on the machine4 ,do the same with the other numbers4 ,do not overload line as this will decrease the life of the contacts4 ,illustration3 ,,figs4 #a1jbc and #a1jbd4--,wiring diagrams for high speeds4 ,where a high speed flasher is used on a spoked wheel containing more lamps in the rim than the number of spokes1 the extra rim lamps must be connected to the spoke circuits1 so that the number of rim circuits will equal the number of spokes2 otherwise1 the rim will appear to travel slower than the spokes4 ,in the case of a sign already in use1 on the front of a building or over the sidewalk1 a stroke can be placed leading to the sign from any point above4 ,the flash goes down and when it hits the sign the latter lights up1 holds a few seconds1 goes out1 and repeats about four times a minute4 ,illustration3 ,,fig4 #a1jbe--;,dull's lightning type flasher for giving the appearance of a streak of lightning going across a display4 ,lightning flashes are not usually constructed for heavy loads1 the one shown in fig4 #a1jbe being designed for two amperes4 ,script ,breakers4--,flashers of this type are used for breaking large script signs1 one socket at a time2 that is1 each lamp is lighted one after another until all are on4 ,after a few seconds they all go out simultaneously and repeat4 ,this gives the appearance of an invisible hand1 writing the name in the darkness1 and is very effective4 ,the result can be accomplished only with script1 and to get the proper effect the smallest letter in a sign should be not less than two feet high2 the larger the letter1 the better the effect4 ,illustration3 ,,fig4 #a1jbf4--;,betts' script breaker 7brush type74 ,this flasher is especially designed for spelling out signs one letter at a time1 or work of a similar nature1 ,the brushes for the revolving cam contacts are of copper1 several leaves thick and provided with special brush holder to prevent loose contact and abnormal burning4 ,script breakers are also used for fancy border signs of other kinds1 and in order to produce these results1 it is necessary that the return wire of every lamp go back to the flashers independently1 which means a wire for each lamp4 ,chaser ,flashers4--,this class of flasher is designed to operate signs whose lamps are arranged to give the effect of snakes chasing each other around the border4 ,this peculiar effect is produced by having a separate wire and a separate switch on the flasher for each two lamps in the border1 and the mechanism so arranged that when the tenth lamp is lighted 7assuming the snake to be ten lamps long7 the first lamp goes out2 when the eleventh is lighted1 the second goes out1 etc41 progressing in this way around the entire border4 ,illustration3 ,,fig4 #a1jbg4--,reynolds chaser type of flasher1 as used on electric signs whose lamps are arranged to give the effect of snakes chasing each other around the border of a sign4 ,in operation1 the lamps are turned on and off so rapidly that it produces the effect of snakes4 ,it is not advisable to build these signs small nor cheaply1 as in order to produce the desired effect1 the curved path taken by the snake should cover at least #aj inches width1 which would mean a total of #bj inches lateral space for the snake in addition to the electric letters in the center4 ,in order to get the proper effect1 the sign should be at least ten feet long4 ,ques4 ,why are chaser signs expensive8 ,ans4 ,it is on account of the care required in their construction1 large amount of wiring necessary and large flasher required4 ,a sign four by ten feet outside dimensions1 would require in the neighborhood of #aej lamps in the border alone on each side4 ,this would require a flasher with #ge switches and about #hb wires to run between the sign and flasher4 ,illustration3 ,,fig4 #a1jbh4--;,chaser wiring diagram for two snakes4 ,draw a line diagonally through the sign 7as shown in dotted line7 so that one-half the total lamps will be on either side4 ,begin to number from one consecutively to the line4 ,over the line commence again at #a and number as before4 ,for three snakes1 divide total lamps into three parts and number as before4 ,in each case1 connect all lamps of the same number to the same wire whether the sign be single or double face4 ,the wire containing all the ,no4 #a lamps goes to the ,no4 #a switch on the flasher1 and the remaining sets are connected similarly4 ,ques4 ,how are chaser signs worked8 ,ans4 ,there are several ways of operating these signs4 ,the border is generally working continuously1 while the center can be flashed or not1 as may be desired4 ,flashing the wording reduces the current expense1 which offsets in a measure the extra cost of the sign4 ,the border1 although working continuously consumes very little current4 ,ques4 ,what is the relative cost of a one snake sign as compared with a two snake sign8 ,ans4 ,one snake running around the border would cost twice as much for flasher and wiring as a two snake flasher4 ,three snakes would cost about #be per cent4 less for flasher and wiring than for two snakes4 ,the smaller the number of snakes travelling around the border at one time1 the greater the expense of wiring and flasher4 ,illustration3 ,,fig4 #a1jbi4--,thermo flasher4 ,it consists of two metal strips1 one of brass and the other of iron1 about #ex x #a_/cb each4 ,the brass strip is provided with a winding of fine wire over asbestos and the two strips are connected to the base as shown4 ,one terminal of the winding is connected to ,j1 and the other end to ,m4 ,at the end of the strips is a small contact screw ,n with locknut ,o1 and below is a contact plate ,l1 fastened to the base and terminal post ,r4 ,the flasher is connected at ,p and ,r in series with the lamp it is to flash1 and ,n adjusted so that it clears the plate about #a_/cb inch when there is no current flowing in the winding4 ,when the switch is turned on there will be a current through the lamp and winding in series4 ,the brass strip will be heated more than the iron and it will expand more1 thus forcing the point of the screw ,n down upon the brass plate1 which will result in the winding about the brass strip being shorted and the full voltage will be impressed upon the lamp1 and it will burn at normal candle power4 ,when the coil is shorted there will of course be no current in its winding and the brass strip will cool down1 the screw ,n will finally be drawn away from contact with the brass plate1 and the winding again connected in series with the lamp4 ,the lamp will apparently go out when the winding is in series with it1 as the total resistance of the lamp and winding combined will not permit sufficient current to pass through the lamp to make its filament glow4 ,the time the lamp is on and off may be varied to a certain extent by adjusting the screw ,n4 ,ques4 ,how many snakes should there be for best effect8 ,ans4 ,two is considered best4 ,three may be used on some signs1 but more than four would1 in most cases1 so crowd them as to spoil the effect entirely4 ,thermo ,flashers4--,these flashers work on the thermo or heat expansion principle1 that is1 the movement of the contact points of the flasher necessary to open and close the circuit is obtained automatically by the alternate heating and cooling of the metal of the flasher1 which causes it to expand and contract4 ,illustration3 ,,fig4 #a1jcj4--,thermal flasher4 ,this simple flasher consists of a brass strip fixed at each end to a porcelain base and slightly arched upwards4 ,the amount of this arching1 however1 is much less than is shown in the figure4 ,the center of the strip carries a platinum contact on its upper surface1 and opposite this is a platinum tipped contact screw which is carried in a brass angle piece fixed to the base4 ,one terminal is fitted on one end of the strip1 and the other is connected1 through the angle piece1 with the contact screw4 ,the strip is wound from end to end with an insulated resistance wire1 one end of this being soldered to the strip1 and the other connected to the right hand terminal4 ,when this device is switched into circuit with the lamps1 the current first flows through the resistance1 which cuts it down so much that the lamps are not visibly affected4 ,the heat generated in the resistance causes the strip to curve still more1 till at length contact is made1 the resistance short circuited1 and the lamps lighted4 ,illustration3 ,,fig4 #a1jca4--;,general ,electric thermal flasher4 ,it consists of a small brass cylinder fixed at its left hand end to one of the terminal blocks4 ,the junction between the two is hidden by a portion of the cover1 which is shown broken away4 ,the right hand end of the cylinder carries a cross piece bearing a platinum contact2 and opposite this is the platinum tip of a contact screw carried in the other terminal block4 ,the cylinder is wound with a heating coil of manganin resistance wire1 one end being soldered to the cylinder and the other to the right hand terminal4 ,when the current is switched on1 the coil and the cylinder warm up and the cylinder elongates sufficiently to make contact and light the lamps4 ,the coil being then short circuited1 it and the cylinder cool down1 and contact is broken1 whereupon the coil is put in circuit once more1 and warms up again4 ,in some sizes of this flasher1 the contact gap is shunted by a small condenser fitted beneath the base4 ,this helps to eliminate the sparking at the contacts4 ,carriage ,calls4--,these are used to avoid the confusion and noise at the theatre1 club house or department store when vehicles are called by a megaphone4 ,illustration3 ,,fig4 #a1jcb4--,monogram or unit for carriage call or talking sign4 ,it consists of a collection of metal compartments each arranged to receive an incandescent lamp4 ,the purpose of these compartments is to confine the light to a certain space1 thus forming a clearly defined number or letter which can be read from a distance4 ,illustration3 ,,fig4 #a1jcc and #a1jcd4--,wiring diagrams showing proper methods of wiring for illuminating a painted sign4 ,the lamps are placed about one foot apart in an overhead inverted trough4 ,they should project out in front of the sign one-half its width1 but no sign should be more than eight feet wide1 as ordinary #af c4p4 lamps will not carry any farther4 ,black and white paint only should be used4 ,the lamps may be flashed on and off as a whole1 saving one-half the current1 or they can be flashed in different colors as desired4 ,for flashing in colors1 only red and amber should be used4 ,no other colors1 such as green1 blue1 etc41 will give sufficient light to produce a good effect4 ,the call itself consists of two or more sheet steel boxes1 one of which is shown in fig4 #a1jcb1 with incandescent lamps arranged in metal compartments in such order that any number may be produced by lighting the proper lamps4 ,illustration3 ,,fig4 #a1jce4--,operating keyboard for three number ,national carriage call4 ,the keyboard here shown is designed to control a three number call1 there being a row of keys for each monogram or unit of the call4 ,its dimensions are #d inches deep1 #ah inches wide and #ai inches long4 ,the base is of slate4 ,there are fourteen wires for each monogram and one return wire1 coming out of the call4 ,the flashing of the number is controlled by a keyboard or switch which may be placed in any convenient location4 ,when the switch and call are connected together1 any numeral may be flashed by pressing the corresponding key4 ,the numeral automatically remains lighted until the releasing button is pressed4 ,illustration3 ,,fig4 #a1jcf4--;,clock monogram or electric sign clock1 operated by the mechanism shown in fig1 #a1jcg4 ,illustration3 ,,fig4 #a1jcg4--;,betts' clock mechanism for operating electric monogram time flasher4 ,the secondary mechanism consists of a three cylinder flasher and is controlled by a master clock which transmits an electric impulse through a relay switch one each minute4 ,this flashes the time in figures on the monogram1 viz43 #aa4de1 #aa4df1 #aa4dg1 #aa4dh1 etc4 ,the first monogram to the left consists simply of a vertical row of lights representing the figure one4 ,each of the other monograms of metal compartments so arranged that any figure may be produced by lighting the proper combination of lamps4 ,talking ,signs4--,this type of electric sign automatically flashes out in brilliant letters1 different phrases or announcements4 ,these are flashed out repeatedly and continuously during the operation of the sign and the changes follow each other without intermission of darkness4 ,illustration3 ,,fig4 #a1jch4--,two way thermal flasher4 ,the moving portion consists of a rocking arm ,a pivoted at p1 and carrying two sealed bulbs1 ,b1 ,b'1 whose bottoms are united by the tube ,t4 ,inside there is sufficient mercury ,m to fill ,t and the bottoms of the bulbs1 the remainder containing air4 ,at each end of ,a is fixed an insulating block ,i1 ,i'1 carrying two contact prongs ,p and ,p'1 which are connected together at the top through heater wires ,h1 ,h' sealed in the bulbs ,b and ,b' respectively4 ,,mc1 ,,mc' are pairs of mercury cups1 the further one of each pair whose stud is marked 1 being connected together to the positive pole of the circuit1 while the front ones are joined up to the respective groups of lamps4 ,the action is as follows3 ,if the apparatus be in the position illustrated1 when the circuit is closed at the time ,p is down1 lamp group ,no4 #a will light up1 the current passing through ,h on its way4 ,the air in ,b consequently expands1 and gradually forces the mercury down in ,b1 along ,t1 and up in ,b'4 ,the arm ,a will gradually become horizontal1 and will then overbalance1 ,p being withdrawn from ,,mc1 and ,p' dipped into ,,mc'4 ,lamp group ,no4 #a will consequently be extinguished and lamp group ,no4 #b lighted2 ,h will cool down1 and ,h' will warm up4 ,thus1 in due course1 ,a will be tilted the other way again4 ,the talking sign consists of any desired number of monograms or units1 in each of which any letter or figure can be formed by lighting certain combinations of incandescent lamps4 ,a unit is shown in fig4 #a1jcb4 ,the lamps are controlled by a simple mechanical arrangement operated by a small motor4 ,any reading matter can be flashed by properly setting the mechanism4 ,the flashing of the letters or numerals in the monogram is controlled by commutators1 one commutator being required for each monogram1 except for a double faced sign where the corresponding monogram on each side is controlled by the same commutator4 ,,chapter ,,xliii ,,lightning ,,protection ,a lightning arrester is an apparatus designed to provide a path by which lightning disturbances or other static discharges may pass to earth4 ,lightning arresters may be divided into three classes1 according as their action depends upon the effects of3 #a4 ,sharp points2 #b4 ,air gaps2 #c4 ,sharp turns4 ,lightning ,rods4--,this form of arrester consists of a conducting rod or cable erected on the outside of a building and connected to earth1 in order to afford protection from lightning by carrying the lightning discharge into the ground2 or to prevent lightning by leading the electricity from the earth to the cloud without disturbance4 ,ques4 ,why do lightning rods terminate in sharp points8 ,ans4 ,the action of the rod depends on the discharging effect of a sharp point as follows3 ,when an electrically charged cloud approaches a building provided with a lightning rod1 it induces an opposite charge in the earth and in the rod which is connected to the earth4 ,as soon as the charge on the point becomes strong enough to break apart the molecules of the air in front of it1 a stream of electrified particles1 opposite in sign to that of the charge on the cloud1 passes from the neighborhood of the rod to the cloud and thus neutralizes the charge of the cloud4 ,ques4 ,how should a lightning rod be erected8 ,ans4 ,the conductor should be carried to all high points of the building it is to protect and should be well insulated from the latter and grounded in deep wet earth1 independent of gas or water pipes4 ,sharp bends and corners should be avoided4 ,illustration3 ,,fig4 #a1jci4--;,diagram showing principle of air gap arrester3 lightning discharges more readily at sharp points than along flat surfaces4 ,ques4 ,why have lightning rods fallen into disfavor8 ,ans4 ,on account of numerous failures due to faulty installations1 and non-maintenance of the rod in good condition1 also because of the excessive prices charged by unscrupulous dealers for rods and their erection4 ,a lightning rod with defective insulation or broken ground connection is a danger rather than a protection4 ,air ,gap ,arresters4--,many of the lightning arresters used for the protection of electrical apparatus depend upon the fact that lightning discharges will jump across air spaces that are good insulators for the regular working current1 while they find difficulty in passing through circuits containing electromagnets4 ,illustration3 ,,fig4 #a1jdj4--,union lightning arrester and ground wire switch for telegraph lines4 ,two line wires are attached to the two plates provided with points4 ,the ground wire being connected to the third or central plate4 ,the pin serves as a ground wire switch and cut out4 ,this is a good form for short lines4 ,the principle of air gap arresters is illustrated in fig4 #a1jci4 ,there are two brass plates slightly separated2 one is connected to the line and the other is grounded4 ,the air gap between the plates is very small and the resistance thus interposed1 while sufficient to prevent the regular working current jumping across1 is not great enough to interfere with a lightning discharge which readily jumps the gap and passes off to earth4 ,ques4 ,why are teeth provided on the plates8 ,ans4 ,for the same reason that points are used on lightning rods4 ,that is1 when electricity at high pressure accumulates at such points the surrounding air is electrified and the charge escapes by means of the charged air particles4 ,illustration3 ,,fig4 #a1jda4--,mason multi-discharge lightning arrester4 ,the construction of this arrester is based on the well known principle that lightning discharges more readily at points or angles than elsewhere4 ,the wire is wound around square carbon rods1 which are connected to the ground1 the line being insulated from the rods by sheets of mica4 ,the wire itself being square1 instead of round1 adds to the efficiency of the arrester1 by increasing the number of points or angles4 ,ques4 ,for what kind of service is the form of arrester just described used8 ,ans4 ,it is suitable for telegraph and telephone lines where currents of very low voltage are employed4 ,ques4 ,why is it not used on lines employing higher voltage1 such as in electric light and power stations8 ,ans4 ,current at high pressure would follow the lightning across the gap and establish an arc or continuous flame from one plate to the other thus quickly destroying the plates and causing other more serious damage4 ,ques4 ,what provision is made to prevent the destruction of arresters by the line current8 ,ans4 ,lightning arresters used on heavy duty circuits are designed to rupture the arc as soon as formed4 ,illustration3 ,,fig4 #a1jdb4--;,diagram showing operation of variable gap arc breaker used on heavy duty lightning arresters4 ,when a lightning discharge passes across the gap to earth1 the dynamo current follows it and energizes the magnet ,m1 which attracts the short arm of the double lever1 thus quickly jerking the terminal ,b away from ,c4 ,the wider air gap thus interposed between ,b and ,c greatly increases the resistance which breaks the arc4 ,ques4 ,how is this done8 ,ans4 ,there are several methods1 of which may be mentioned the variable gap method described in fig4 #a1jdb1 and the magnetic blow out method shown in fig4 #a1jdc4 ,ques4 ,where should lightning arresters be placed8 ,ans4 ,they should be placed as near as possible to the point where wires enter a building1 and in an easily accessible place away from combustible material4 ,ques4 ,what should be avoided in installing lightning arresters8 ,ans4 ,kinks and sharp bends in the wire running from the outdoor lines to the arresters and from arresters to ground should be avoided as far as possible4 ,ques4 ,why should kinks and sharp bends be avoided8 ,ans4 ,because they offer resistance to the lightning discharge4 ,illustration3 ,,fig4 #a1jdc4--;,horn type lightning arrester4 ,in this type of arrester1 two wires1 after approaching within a short distance of one another1 are bent divergently4 ,these wires are supported on insulators4 ,one of them is connected to the line to be protected and the other is earthed4 ,the normal line pressure is insufficient to bridge the gap1 even at its narrowest portion1 but an extra high pressure whether due to lightning or to other disturbing phenomena1 will bridge the gap at its narrowest point and establish a path to earth4 ,when1 however1 the main current attempts to flow across1 phenomena of electromagnetic repulsion force the arc upward along the horns1 lengthening and attenuating it1 until it finally becomes extinguished4 ,ques4 ,how should lightning arresters be grounded8 ,ans4 ,they should be connected to ground with ,no4 #f ,b4 ,s4 gauge copper wire or larger4 ,gas pipes within a building must not be used for a ground connection4 ,illustration3 ,,fig4 #a1jdd4--;,ground connection for lightning arrester4 ,illustration3 ,,fig4 #a1jde4--;,carbon lightning arrester with fuses as used on telephone lines4 ,the arrester consists of two blocks of carbon separated a small distance by a thin sheet of insulating mica1 which is perforated with one or more holes2 a high voltage charge on the line will jump through the hole in the mica from the carbon on the line side to the lower carbon1 which is connected with the ground2 the fuses protect the instruments against foreign currents which might damage1 although not of sufficiently high pressure to jump to earth2 sometimes the connections are reversed so that the fuse is between the line and the earth4 ,ground connections may be made with a one inch galvanized iron pipe driven about #h feet or until it reaches permanently moist earth1 and extending at least #g feet above ground4 ,the ground wire should be securely soldered to a brass plug firmly screwed into the pipe1 and both strongly stapled to the pole so there will be little danger of the connection being broken4 ,a good ground is important1 as the efficiency of the protection would be impaired if the ground connection were poor4 ,wherever the earth is dry and a good ground cannot surely be obtained1 an excavation #d or #e feet deep should be made1 and after placing the copper ground plate or iron pipe in the hole1 it should be filled with crushed coke or charcoal about pea size4 ,this improves the electrical connection between pipe or plate and earth4 ,ques4 ,does lightning often strike telephone or electric light lines8 ,ans4 ,no1 the lines become charged to a high pressure by induction from lightning flashes or from the passing of clouds that are highly charged4 ,,chapter ,,xliv ,,storage ,,batteries ,introduction4--,the practical development of the storage battery is comparatively recent1 although a knowledge of the phenomena upon which its actions are based1 dates back to #ahja4 ,in #ahjj1 the year made memorable by ,volta's discovery of the galvanic battery1 ,nicholson and ,carlisle found that a current from ,volta's cell could decompose water4 ,in #ahja1 ,gautherot discovered that if two plates of platinum or silver1 immersed in a suitable electrolyte1 be connected to the terminals of an active primary cell and current be allowed to flow1 a small current could be obtained on an outside circuit connecting these two electrodes as soon as the primary battery had been disconnected4 ,erman found that the positive pole of such a cell1 was the pole which had been connected to the positive pole of the battery4 ,in #ahjc1 ,ritter observed1 with gold wire1 the same phenomenon as ,gautherot1 and constructed the first secondary battery1 by superposing plates of gold1 separated by cloth discs1 moistened with ammonia4 ,volta1 ,davy1 ,marianini1 and others added somewhat to the knowledge on the subject1 and in #ahcg1 ,schoenbein found that peroxide of lead could be used in secondary batteries4 ,sir ,william ,grove next came forward with the discovery that metal plates1 with a layer of oxide on them1 acted better than the plain metallic plates1 and ,wheatstone and ,siemens found still later that peroxide of lead was the best for such purposes4 ,in #ahdb1 ,grove constructed a gas battery1 in which the electromotive force came from the oxygen and hydrogen evolved in the electrolysis of water acidulated with sulphuric acid4 ,by means of fifty such cells1 he obtained an arc light4 ,michael ,faraday1 when electrolyzing a solution of lead acetate1 found that peroxide was produced at the positive1 and metallic lead at the negative pole1 and in his ,experimental ,researches1 he comments on the high conductivity of lead peroxide1 and its power of readily giving up its oxygen4 ,although he made no apparent use of this discovery1 it may be considered as the next important step in the development of the storage battery4 ,according to ,niblett1 ,wheatstone1 de la ,rue1 and ,niaudet were well aware that peroxide of lead was a powerful depolarizer1 but nobody appears to have made use of this fact until #ahfj1 when ,m4 ,gaston ,plante constructed his well known cell with coiled plates4 ,plante's researches extended up to #ahgi1 and practically determined the state of the art4 ,illustration3 ,,fig4 #a1jdf4--,one plate or grid of a type of storage cell constructed by inserting buttons or ribbons of the proper chemical substances in perforations4 ,some such cells use crimped ribbons of metallic lead for inserting in the perforations1 others pure red lead or other suitable material4 ,as to the theory at this time1 it may be stated that ,clerk ,maxwell1 although the leading electrician of his time1 speaks of the storage battery as storing up a quantity of energy in a manner somewhat analogous to the ordinary condenser2 hence the use of the word accumulator for storage battery4 ,in #ahgi1 ,r4 ,l4 ,metzer did away with the tedious forming process1 by mechanically applying the active material4 ,this important discovery was not1 however1 generally known1 until #ahha1 when ,camille ,faure obtained important patents concerning the method of shortening the time of formation4 ,charles ,f4 ,brush1 working independently of either ,faure or ,metzer1 arrived at the same result1 and the ,united ,states courts have decided1 after long litigation1 that to him belongs the priority of invention in this country4 ,illustration3 ,,figs4 #a1jdg to #a1jej4--;,electric ,storage ,battery ,co4 plates4 ,fig4 #a1jdg1 ,manchester positive plate2 fig4 #a1jdh1 box negative plate2 fig4 #a1jdi1 ,tudor positive plate2 fig #a1jej1 pasted negative plate4 ,ques4 ,to what use is the storage battery sometimes put in electric lighting or power stations8 ,ans4 ,to carry the peak of the load2 that excessive portion of the load which1 for instance1 in electric lighting stations has to be carried only for two or three hours a day4 ,to carry the entire load at minimum hours4 ,to act as equalizer or reservoir4 ,also for equipment of annex or substations4 ,illustration3 ,,fig4 #a1jea4--,unformed plate of one pattern of ,gould storage cell4 ,the particular plate shown has total outside dimensions of #ff inches4 ,the clear outline of the grooves indicates absence of oxides1 due to action of forming solutions1 or charging current4 ,theory of the ,storage ,battery4--,the action of the storage battery is practically the same as that of the primary battery and it is subject to the same general laws4 ,the cells of a storage battery are connected in the same way as primary cells1 and when charged is capable of generating a current of electricity in a manner similar to that of a primary battery4 ,it differs1 however1 from the primary battery in that it is capable of being recharged after exhaustion by passing an electric current through it in a direction opposite to that of the current on discharge4 ,this difference constitutes the principal advantage of the storage battery over the primary battery4 ,illustration3 ,,figs4 #a1jeb and #a1jec4--;,electric ,storage ,battery ,co41 type ,h exide plates4 ,this form of plate is used for large stand by batteries4 ,fig4 #a1jeb1 positive plate2 fig4 #a1jec1 negative plate4 ,ques4 ,describe a storage cell4 ,ans4 ,a storage cell consists of plates or of grids in an electrolyte1 of such a character that the electrical energy supplied to it is converted into chemical energy 7a process called charging74 ,the chemical energy can be reconverted into electrical energy 7a process called discharging74 ,ques4 ,describe the electrolyte generally used4 ,ans4 ,it consists of a weak solution of sulphuric acid which permits ready conduction of the current from the primary battery1 the greater the proportion of acid within certain limits1 the smaller the resistance offered4 ,illustration3 ,,fig4 #a1jed4--;,elements of #f volt #dj ampere hour ,aplco portable 7#c cell7 storage battery4 ,the grids are made from an alloy of lead and antimony2 hard lead straps which are burned together1 are used for joining the plates4 ,specially treated separators are used4 ,ques4 ,what is the effect of the current passing through the electrolyte8 ,ans4 ,it decomposes the water into oxygen and hydrogen2 this is indicated by the formation of bubbles upon the exposed surfaces of both plates1 these bubbles being formed by oxygen gas on the plate connected to the positive pole of the primary battery1 and hydrogen on the plate connected to the negative pole4 ,because1 however1 the oxygen is unable to attack either platinum or silver under such conditions1 the capacity of such a device to act as an electrical accumulator is practically limited to the point at which both plates are covered with bubbles4 ,after this point the gases will begin to escape into the atmosphere4 ,ques4 ,what is the prime condition for operation of a storage battery8 ,ans4 ,the resistance of the electrolyte should be as low as possible in order that the current may pass freely and with full effect between the electrodes4 ,if the resistance of the electrolyte be too small1 the intensity of the current will cause the water to boil rather than to occasion the electrolytic effects noted above4 ,ques4 ,what happens when the charging current is discontinued1 and the two electrodes joined by an outside wire8 ,ans4 ,a small current will flow through the outside circuit1 being due to the recomposition of the acid and water solution4 ,the process is in a very definite sense a reversal of that by which the current is generated in a primary cell4 ,hydrogen collected upon the negative plate1 which was the cathode1 so long as the primary battery was in circuit1 is given off to the liquid immediately surrounding it1 uniting with its particles of oxygen and causing the hydrogen1 in combination with them1 to unite with the particles of oxygen next adjacent4 ,the process is continued until the opposite positive plate is reached1 when the oxygen collected there is finally combined with the surplus hydrogen1 going to it from the surrounding solution4 ,this chemical process causes the current to emerge from the positive plate1 which was the anode1 so long as the primary battery was in circuit4 ,the current thus produced will continue until the recomposition of the gases is complete2 then ceasing because these gases1 as before stated1 do not combine with the metal of the electrodes4 ,types of ,storage ,battery4--,there are three classes of storage cell which are commercially important3 #a4 ,plante cells2 #b4 ,faure cells2 #c4 ,alkaline cells4 ,according to construction secondary cells may be classified as follows3 #a4 ,lead sulphuric acid cells2 #b4 ,lead copper cells2 #c4 ,lead zinc cells2 #d4 ,alkaline zincate cells4 ,the lead sulphuric acid type includes all those cells belonging to the ,plante and ,faure groups4 ,lead copper cells consist of sheets of metal coated with lead oxide1 serving as the positive electrode1 and copper plates for the negative electrodes4 ,these plates are immersed in a solution of copper sulphate4 ,cells belonging to this class are not employed in commercial practice1 being useful only for laboratory experiments4 ,lead zinc cells are similar to the preceding type1 but differ by having zinc for the negative electrode1 and zinc sulphate for the electrolyte4 ,the voltage of these cells is slightly higher than that of the ordinary cell1 and their capacity per unit of total weight is high1 but they are apt to lose their charge on open circuit1 besides they possess most of the disadvantages of the ,plante cells4 ,alkaline zincate cells have copper for the positive1 and iron for the negative electrode4 ,the electrolyte is composed of sodium1 or potassium1 zincate4 ,cells of this type are used to some extent for traction purposes4 ,in addition to the above there are some special forms of cell which do not belong to the four preceding types4 ,ques4 ,describe the ,plante type4 ,ans4 ,in the ,plante type the lead is chemically attacked and finally converted into lead peroxide1 probably after it has gone through several intermediate changes4 ,the plates are all formed as positive plates first and then all that are intended for negative plates are reversed1 the peroxide being changed into sponge lead4 ,illustration3 ,,figs4 #a1jee and #a1jef4--,willard plates2 fig4 #a1jee1 negative plates2 fig4 #a1jef1 positive plates4 ,both positive and negative plates are of the ,plant type1 made from one integral piece of rolled lead4 ,these are grooved plates4 ,the projections are tapered1 that is1 they are wider at the base than at the surface1 for strength4 ,the center web of each positive plate is tapered from the top of the plate downward to secure uniform distribution of the current all over the surface of the plate4 ,illustration3 ,,fig4 #a1jeg4--,wood separator for spacing the plates1 as used in the ,willard storage cells4 ,illustration3 ,,fig4 #a1jeh4--,positive plate4 ,illustration3 ,,fig4 #a1jei4--,perforated rubber separator4 ,illustration3 ,,fig4 #a1jfj4--,wood separator4 ,illustration3 ,,fig4 #a1jfa4--,negative plate4 ,illustration3 ,,fig4 #a1jfb4--;,hard rubber cover4 ,illustration3 ,,fig4 #a1jfc4--,vent plug4 ,illustration3 ,,fig4 #a1jfd4--,pillar connecting strap4 ,illustration3 ,,fig4 #a1jfe4--;,hard rubber jar4 ,illustration3 ,,fig4 #a1jff4--;,complete element4 ,illustration3 ,figs4 #a1jeh to #a1jff4--,parts of the ,willard ,autex automobile cells4 ,ques4 ,what is done to make the ,plante plate more efficient8 ,ans4 ,the surfaces are finely subdivided1 the following methods being those common3 scoring1 grooving1 casting1 laminating1 pressing1 and by the use of lead wool4 ,ques4 ,describe the ,faure or pasted type4 ,ans4 ,this form of plate is constructed by attaching the active material by some mechanical means to a grid proper4 ,the active material first used for this purpose was red lead1 which was reduced in a short time to lead peroxide when connected as the positive or anode1 or to spongy metallic lead when connected as the cathode or negative1 thus forming plates of the same chemical compound as in the ,plante type4 ,the materials used at the present time by the manufacturers for making this paste are largely a secret with them1 but in general they consist of pulverized lead or lead oxide mixed with some liquid to make a paste4 ,ques4 ,how do ,faure plates compare with those of the ,plante type8 ,ans4 ,they are usually lighter and have a higher capacity1 but have a tendency to shed the material from the grid1 thus making the battery useless4 ,many ways have been tried for mechanically holding the active material on the grid1 the general method involving a special design in the shape of the grid4 ,some of these designs are3 #a1 solid perforated sheets of lattice work2 #b1 corrugated and solid recess plates not perforated2 #c1 ribbed plates with projecting portions2 #d1 grid cast around active material2 #e1 lead envelopes1 and #f1 triangular troughs as horizontal ribs4 ,the ,electrolyte4--,sulphuric acid is generally used as electrolyte2 the acid should be made from sulphur and not from pyrites1 as the latter is liable to contain injurious substances4 ,ques4 ,how is the electrolyte prepared8 ,ans4 ,one part of chemically pure concentrated sulphuric acid is mixed with several parts of water4 ,the proportion of water differs with several types of cell from three to eight parts1 as specified in the directions accompanying the cells4 ,illustration3 ,,figs4 #a1jfg to #a1jgi4--,willard connecting straps and connectors4 ,ques4 ,what test is necessary in preparing the electrolyte8 ,ans4 ,in mixing the water and acid1 the hydrometer should be used to test the specific gravity#f of both the acid and the solution4 ,the most suitable acid should show a specific gravity of about #a4gfj or #ff ,baum4 #f ,,note4--,specific gravity is the weight of a given substance relative to an equal bulk of some other substance which is taken as a standard of comparison4 ,water is the standard for liquids4 ,in the laboratory the specific gravity bottle is often used in determining the specific gravity of a liquid4 ,the capacity of the bottle is #a1jjj grains of pure water4 ,when it is filled with spirits of wine and weighed in a balance 7together with a counterpoise for the weight of the bottle1 which of course is constant71 it will weigh considerably less than #a1jjj grains2 in fact1 the bottle will contain only about #iag grains of proof spirit2 therefore1 taking the specific gravity of water as unity1 #a or #a4jjj1 the specific gravity of spirits of wine is #j4iag4 ,if1 on the other hand1 the bottle be filled with sulphuric acid1 it will weigh about #a1hej grains2 hence1 the specific gravity of sulphuric acid is said to be #a4hej4 ,a more convenient method for the automobilist is by the use of the hydrometer4 ,ques4 ,in preparing the electrolyte1 how should the water and acid be mixed8 ,ans4 ,the mixture should be made by pouring the acid slowly into the water1 never the reverse4 ,as cannot be too strongly stated1 in mixing1 the liquid should be stirred with a clean wooden stick1 the acid being added to the water slowly2 the latter is corrosive and will painfully burn the flesh4 ,distilled or rain water should be used in preparing the electrolyte4 ,when made1 the solution should be allowed to cool for several hours or until its temperature is approximately that of the atmosphere 7#fj being the average74 ,at this point it should have a specific gravity of about #a4bjj or #be ,baum4 ,if the hydrometer show a higher reading1 water may be added until the correct reading is obtained2 if a lower reading1 dilute acid may be added with similar intent4 ,the electrolyte should never be mixed in jars containing the battery plates1 but preferably in stone vessels1 specially prepared for the purpose4 ,furthermore1 it should never be placed in the cell until perfectly cool4 ,ques4 ,what is the effect of mixing the acid and the water8 ,ans4 ,the mixture becomes hot4 ,before using1 the mixture should be allowed to cool4 ,ques4 ,what kind of a vessel should be used8 ,ans4 ,the vessel should be of glass1 glazed earthenware1 or lead4 ,ques4 ,at what density is the resistance of dilute sulfuric acid at a minimum8 ,ans4 ,at #a4bfj4 ,the percentage of concentrated sulphuric acid and of water per #ajj parts of the electrolyte for various specific gravities is given by the following table3 ,,specific ,,gravity ,,table ---------------------------------------- ---------------------------------------- ---- ,sulphuric acid ,water ,specific gravity 7,per cent474 7,per cent474 of ,mixture4 ---------------------------------------- ---------------------------------------- ---- #ej #ej #a4cih #dg #ec #a4cgj #dd #ef #a4cdb #da #ei #a4cae #ch #fb #a4bhi #ce #fe #a4bfd #cb #fh #a4bci #bi #ga #a4bae #bf #gd #a4aij #bc #gg #a4afg #bj #hj #a4add #ag #hc #a4aba #ad #hf #a4jih #aj #ij #a4jfh ---------------------------------------- ---------------------------------------- ---- ,the electrolyte of the desired specific gravity may be purchased ready for use1 but in cases where it is desirable to save freight1 the acid may be diluted at the point of installation4 ,ques4 ,what is the effect of a deep containing vessel8 ,ans4 ,parts of the plate surface may do more than their share of the work due to the difference in the density of the electrolyte at the top and bottom4 ,the containing vessel should1 therefore1 never be deeper than about #bj inches unless some artificial means of acid circulation be used4 ,ques4 ,what is the effect of changes in temperature on the electrolyte8 ,ans4 ,the resistance of the electrolyte is changed1 being less for increase of temperature4 ,illustration3 ,,figs4 #a1jhj to #a1jhd--;,acid hydrometers for liquids heavier than water4 ,fig4 #a1jhj1 standard storage battery hydrometer with guiding points designed for hydrometer syringe1 shot bulb1 with red line at #be ,baum1 #e inches long1 double scale #aj to #dj ,baum1 #a4jej to #a4djj specific gravity4 ,fig4 #a1jha1 plain hydrometer with shot bulb1 #e inches long1 double scale #aj to #dj ,baum1 #a4jej to #a4djj specific gravity4 ,figs4 #a1jhb and #a1jhc1 hydrometer with small flat bulb1 used in car lighting batteries1 shot bulb1 #d inches long1 single scale1 reading from #a4ajj to #a4bej specific gravity4 ,fig4 #a1jhd jar for hydrometers4 ,ques4 ,how should the cells be filled8 ,ans4 ,enough of the electrolyte should be poured into the jars to completely cover the plates1 or to within about a half inch of the top edge of the jar4 ,large cells should be filled by means of an acid proof pump and rubber hose4 ,ques4 ,what change takes place after filling the jars8 ,ans4 ,the specific gravity of the electrolyte will fall considerably1 but will rise again when the battery is charged4 ,ques4 ,what may be said with respect to the density of the electrolyte8 ,ans4 ,it should never exceed #a4bjj when the battery is fully charged4 ,ques4 ,how much electrolyte is used per #ajj ampere hours battery capacity1 on an #h hour rating8 ,ans4 ,about ten pounds2 in automobile batteries1 about four pounds is sufficient4 ,illustration3 ,,fig4 #a1jhe4--,the hydrometer syringe2 a convenient device for testing electric vehicle cells4 ,by slightly compressing the bulb and inserting the slender tube through the vent hole in the cover of the cell sufficient acid may be drawn up to float the hydrometer within the large glass tube1 and the reading can be made at once4 ,the acid is returned to the cell by again compressing the bulb1 and the reading of the next cell taken4 ,the laborious and uncleanly method of drawing out sufficient acid by a syringe is thus avoided4 ,ques4 ,what may be said with respect to impurities in the electrolyte8 ,ans4 ,the electrolyte should be free from chlorine1 nitrates1 acetates1 iron1 copper1 arsenic1 mercury1 and the slightest trace of platinum4 ,mercury alone has no injurious effect unless it be present in sufficient quantity to amalgamate the plates1 but in combination with any other metal1 may cause local action4 ,illustration3 ,,figs4 #a1jhf to #a1jhi4--,the ,champion ,accumulator2 views showing parts and assembly4 ,fig4 #a1jhf1 empty plate2 fig4 #a1jhg1 filled plate2 fig4 #a1jhh1 complete element1 small type2 fig #a1jhi1 cell assembled4 ,the plates are of the envelope type and are made thick4 ,the active material is held firmly in place by a covering of lead4 ,a few thick plates are used instead of many thin ones4 ,the following tests should be made for impurities before the electrolyte is poured in the cells3 ,chlorine4--,to a small sample of the electrolyte add a few drops of silver solution 7#bj grains of silver dissolved in #a1jjj cu4 cm4 of water74 ,a white precipitate indicates chlorine4 ,nitrates4--,place some of the electrolyte in a test tube1 and add #aj grains of strong ferrous sulphate solution4 ,carefully pour down the side of the test tube a small amount of chemically pure concentrated sulphuric acid4 ,a brown stratum between the electrolyte and the concentrated acid indicates the presence of nitric acid4 ,acetic acid4--,neutralize the electrolyte with ammonia1 then add ferric chloride4 ,if the solution turns red1 and is afterwards bleached by the addition of hydrochloric acid1 acetic acid is present4 ,iron4--,neutralize a sample of the electrolyte with ammonia2 boil a small portion with hydrogen peroxide1 and add ammonia or caustic potash solution until the mixture becomes alkaline4 ,if a brownish red precipitate forms1 it indicates iron4 ,copper4--,if copper be present1 a bluish white precipitate will be formed when ammonia solution is added to the electrolyte4 ,illustration3 ,,fig4 #a1jij4--,one cell of the ,gould storage battery for electric vehicle use4 ,according to the data given by the manufacturers1 this cell1 containing four negative and three positive plates1 has a normal charging rate of #bg amperes2 a distance rate of #bb amperes for four hours2 a capacity of #ha ampere hours at #c hours discharge1 and of #ij ampere hours at #d hours discharge4 ,forty such cells are generally used for an average light vehicle battery4 ,mercury4--,this is indicated by an olive green precipitate when a solution of potassium iodide is added to the electrolyte1 or by a black precipitate when lime water is added4 ,platinum4--,a rough test for traces of platinum is made by pouring the electrolyte into a cell in which the battery plates are immersed4 ,if gassing take place for some time on open circuit1 it is an indication of the presence of platinum4 ,ques4 ,what should be done with old electrolyte8 ,ans4 ,when a battery is taken down the electrolyte may be saved and used when re-assembling the battery1 providing great care be exercised when pouring it out of the jar1 so as not to draw off with it any of the sediment4 ,it should be stored in convenient receptacles1 preferably carboys1 which have been thoroughly washed and never used for any other purpose4 ,illustration3 ,,fig4 #a1jia4--,phantom view of an ,exide sparking or ignition battery4 ,it contains three cells4 ,in this type1 the terminal lug has been designed to obviate the creeping of the electrolyte with its accompanying corrosion4 ,the positive and negative terminals are for identification4 ,the electrolyte saved in this manner will not1 however1 be sufficient to refill the battery1 and as some new electrolyte will be required1 in general it is recommended that the old supply be thrown away and all new electrolyte 7#a4bjj specific gravity7 be used when re-assembling4 ,voltage of a ,secondary ,cell4--,this depends on the density of the electrolyte1 the character of the electrodes and condition of the cell2 it is independent of the size of the cell4 ,the voltage of a lead sulphuric acid cell when being charged is from #b to #b4e volts4 ,while the cell is being discharged1 it decreases from #b to #a4g volts4 ,the voltage due to the density of the electrolyte may be calculated from the following formula3 ,v #a4he 4#iag 7,s - s7 in which ,v voltage2 ,s specific gravity of the electrotype2 s specific gravity of water at the temperature of observation4 ,illustration3 ,,fig4 #a1jib4--,the ,exide storage cell4 ,the positive and negative plates are separated by thin sheets of perforated hard rubber1 placed on both sides of each positive plate4 ,the electrolyte and plates are contained in a hard rubber jar4 ,illustration3 ,,fig4 #a1jic4--;,an ,exide battery of five cells4 ,the box which holds the cells is usually made of oak1 properly reinforced1 with the wood treated to render it acid proof4 ,the terminals as shown1 consist of metal castings attached to the side of the box and plainly marked4 ,connection for ,charging4--,the dynamo cable connections may be made either before or after filling the cells4 ,in making these connections great care should be taken to be sure that the positive terminal of the battery is connected to the positive lead of the dynamo1 and that the negative terminal of the battery is connected to the negative lead of the dynamo4 ,in order to insure that the reverse connections are not made accidentally1 the dynamo leads should be tested by a pole tester1 and the positive and negative poles marked red and black respectively4 ,illustration3 ,,figs4 #a1jid to #a1aji4--,parts of the ,exide sparking battery4 ,a1 positive plate2 ,b1 negative plate2 ,c1 wood separator2 ,d1 positive strap2 ,e1 negative strap2 ,f1 terminal lug2 ,h1 connector2 ,i1 terminal bolt connector1 stud1 thumb nut and hexagonal nut2 ,j1 copper washer for bolt connector2 ,l1 hard rubber jar2 ,m1 hard rubber cover2 ,n1 hard rubber cylinder vent2 ,o1 vent plug for cylinder vent2 ,r1 wood case2 ,s1 strap handle2 ,t1 fitting for strap handle4 ,the ,exide sparking battery is also adapted for electric lighting of automobiles1 for head lights1 tail lights1 side and interior lights4 ,the polarity of the dynamo wires being determined1 they may be joined to the proper terminals by means of suitable clamps or by solder4 ,wherever possible the dynamo should be of the direct current1 shunt wound1 or special compound type1 but in cases where only alternating current can be obtained1 suitable rectifiers or converters should be used for changing it to direct current4 ,charging4--,before beginning to charge a storage battery1 it should be gone over carefully1 and any cell that is not up to the standard should be disconnected and put in working order before being replaced4 ,in general1 if the current used in charging be too large1 it will waste energy by evolving an excess of heat and gas2 if too small1 an insulating deposit of white lead sulphate will be formed on the positive plate1 thereby preventing the formation of the proper amount of lead peroxide4 ,illustration3 ,,figs4 #a1aaj and #a1aaa4--,switchboard and motor dynamo circuit connections for charging a battery from direct current mains4 ,ques4 ,how should a battery be charged for the first time8 ,ans4 ,it is essential that the current be allowed to enter at the positive pole at about one-half the usual charging rate prescribed1 but after making sure that all necessary conditions have been fulfilled1 it is possible to raise the rate to that prescribed by the manufacturers of the battery4 ,ques4 ,what is the usual period for charging a new battery8 ,ans4 ,with several of the best known makes of storage battery the prescribed period for the first charge varies between twenty and thirty hours4 ,illustration3 ,,figs4 #a1aab and #a1aac4--,switchboard and motor generator circuit connections for charging a battery from alternating current mains4 ,the connections of a third wire are shown1 for use in case a three phase circuit is available4 ,ques4 ,how is the electrolyte affected by the first charge8 ,ans4 ,a change of specific gravity occurs4 ,the specific gravity should be about #a4bjj when the solution is poured into the cells4 ,at the completion of the first charge1 it should1 on the same scale be about #a4bbe4 ,if it be higher than this1 water should be added to the solution until the proper figure is reached1 if it be lower1 dilute sulphuric acid should be added until the hydrometer registers #a4bbe4 ,at the first charging of a cell1 when the pressure has reached the required limit1 the cell should be discharged until the voltage has fallen to about two-thirds normal pressure1 when the cell should again be recharged to the normal voltage 7#b4e or #b4f volts74 ,the manufacturers of a well known cell of the ,plante genus prescribe for the first charge1 half rate for four hours1 after which the current may be increased to the normal power and continued for twenty hours successively4 ,illustration3 ,,fig4 #a1aad4--,plates of ,edison storage battery4 ,the positive or nickel plate consists of one or more perforated steel tubes1 heavily nickel plated1 filled with alternate layers of nickel hydroxide and pure metallic nickel in excessively thin flakes4 ,the tube is drawn from a perforated ribbon of steel1 nickel plated1 and reinforced with eight steel bands1 equidistant apart1 which prevent the tube expanding away from and breaking contact with its contents4 ,the tubes are flanged at both ends and held in perfect contact with a steel supporting frame or grid made of cold rolled steel1 nickel plated4 ,the negative or iron plate consists of a grid of cold rolled steel1 nickel plated1 holding a number of rectangular pockets filled with powdered iron oxide4 ,these pockets are made up of very finely perforated steel1 nickel plated4 ,after the pockets are filled they are inserted in the grid and subjected to great pressure between dies which corrugate the surface of pockets and force them into good contact with the grid4 ,ques4 ,what strength of current should be used in charging a cell8 ,ans4 ,it should be in proportion to the ampere hour capacity of the cell4 ,thus1 as given by several manufacturers1 the normal charging rate for a cell of #dj ampere hours should be five amperes1 or one-eighth of its ampere hour rating in amperes of charging current4 ,ques4 ,what should be the voltage of the charging current before closing the charging circuit8 ,ans4 ,the voltage should be at least ten per cent4 higher than the normal voltage of the battery when charged4 ,illustration3 ,,fig4 #a1aae4--;,complete element of ,edison storage battery with insulators4 ,after the plates are assembled into a complete element1 narrow strips of treated hard rubber are inserted between the plates1 thereby separating and insulating them from each other4 ,the side insulator is provided with grooves that take the edges of the plates1 thereby performing the dual function of separating the plates and insulating the complete elements from the steel container4 ,at the ends of the element1 that is between the outside negative plates and container1 are inserted smooth sheets of hard rubber4 ,at the bottom1 the element rests upon a hard rubber rack or bridge1 insulating the plates from the bottom of container4 ,illustration3 ,,fig4 #a1aaf4--;,four ,edison cells 7type ,a-#d7 in wooden tray4 ,ques4 ,what indicates the completion of a charge8 ,ans4 ,when a cell is fully charged the electrolyte apparently boils and gives off gas freely4 ,the completion of a charge may be determined by the voltmeter1 which will show whether the normal pressure has been attained4 ,ques4 ,how should the voltage be regulated during the first charge8 ,ans4 ,it should be allowed to rise somewhat above the point of normal pressure4 ,electrical ,data ,edison ,cell ---------------------------------------- ---------------------------------------- ---------------------------------------- ---- ,b-#b ,b-#d ,b-#f ,normal output1 ampere hours #dj #hj #abj ,maximum output1 ampere hours #dh #ie #adb ,normal rate of discharge1 amperes for five hours #h #af #bd ,average voltage on normal discharge #a4b #a4b #a4b ,normal rate of charge1 amperes for seven hours #h #af #bd ,maximum rate of boosting charge 7for short time only7 #ej #ajj #adj ,length of containing can 7determined by number of plates7 #a #b #c-ac_/af ,width of containing can #e #e #e ,height #g-ae_/af #g-ac_/af #g ,height over all #h #h #h ,weight of each cell alone1 lbs4 #d4f #g4d #aj4e ,average weight per cell of battery1 assembled in trays #e4e #h4g #aa4h ---------------------------------------- ---------------------------------------- ---------------------------------------- ---- ,illustration3 ,,fig4 #a1aag4--;,cell of ,edison storage battery4 ,the jar or container is of nickel plated sheet steel with welded seams2 the walls are corrugated to give strength4 ,the cell cover1 of sheet steel1 has four mountings1 two being pockets to contain stuffing boxes about the terminal posts4 ,one of the other two is a separator which separates spray from the escaping gas while the battery is charging4 ,the fourth mounting is for filling with electrolyte4 ,the electrolyte consists of a #ba solution of potash in distilled water with a small per cent4 of lithia4 ,the density of the electrolyte does not change on charge or discharge4 ,ques4 ,how often should a battery be charged8 ,ans4 ,at least once in two weeks1 even if the use be only slight in proportion to the output capacity4 ,in charging a storage battery1 it is essential to remember the fact that the normal charging rate is in proportion to the voltage of the battery4 ,thus1 a #ajj ampere hour battery1 charged from a #aaj volt circuit at the rate of ten amperes per hour1 would require ten hours to charge1 and would consume in that time an amount of electrical energy represented by the product of #aaj 7voltage7 by #aj 7amperes7 which would give #a1ajj watts1 or #a kw4 ,illustration3 ,,fig4 #a1aah4--;,diagram illustrating method of charging storage battery of stationary gas engine ignition system2 the system is simple to install and will give satisfactory results4 ,two storage batteries are used1 one being charged while the other is operating the sparking coil4 ,where charging current is available at the point where the batteries are used1 the following diagram shows the system of connections1 which can be easily followed1 ,a represents the source of charging current and ,b the bank of lamps 7or other resistance1 such as an ordinary rheostat7 sufficient to cut down the charging voltage to that required by the battery4 ,c and ,d are two double pole double throw knife switches connected at their hinges to two batteries1 ,e and ,f1 each consisting of a group of cells4 ,g represents the leads to the sparking coil terminals4 ,from the diagram1 it will readily be seen that by throwing the switches in opposite directions one battery will be charging while the other battery is discharging to the engine1 thus giving a constant source of supply1 and insuring that the spare battery will be full and ready for service by the time the other is discharged4 ,the method of determining the necessary resistance for cutting down the line voltage for charging the battery is illustrated by the following example3 ,if a battery require about #c amperes for charging1 how is this current obtained from a #aaj volt circuit8 ,each #af candle power carbon filament lamp in the lamp bank would give approximately ampere with the cells in series in the lamp circuit4 ,therefore1 #c x #c or #i lamps should be used in parallel to give #c amperes4 ,ques4 ,if in charging a battery1 one or more of the cells do not boil at the completion of the charge1 or fail to show the proper voltage1 what should be done8 ,ans4 ,the charging must be continued until the cadmium test shows the required voltage1 but if the prolonging of the charge be liable to damage the plates in the other cells1 the defective cell or cells should be cut out of circuit when the battery discharges and then placed in circuit again when the battery is recharged4 ,if the desired result cannot be attained by this method1 the plates which require additional charging may be charged in a separate cell4 ,illustration3 ,,figs4 #a1aai and #a1abj4--;,emergency connections for weak ignition battery4 ,it sometimes occurs through carelessness or neglect1 that the storage battery is discharged so low that the engine explosion will not take place1 and it is necessary to run somehow or other for a short time4 ,in such cases the following suggestion may be followed3 ,if there be two storage batteries1 connect them in series4 ,if there be one storage battery and a set of dry cells1 connect the positive terminal of the storage battery to the negative or outside terminal of the dry cell2 set and connect to the coil leads as if they were one battery4 ,the above suggestions should only be followed in emergency1 for it may injure the coils1 and is harmful to the battery4 ,ques4 ,how is the cadmium test made8 ,ans4 ,a plate of cadmium is mounted in a hard rubber frame and immersed in the electrolyte4 ,the test consists in taking voltage readings between the cadmium plate and the positive or negative plates of the cell4 ,during charge the cadmium plate reads negative to the negative plate1 until the cell is about full1 when the reading should be zero2 the charge should be continued until the cadmium reads #j4b volt positive to the negative while charging at the normal rate4 ,ques4 ,name some portable instruments that should be provided for testing batteries4 ,ans4 #a1 a hydrometer syringe 7specific gravity tester72 #b1 an acid testing set 7can be used instead of the syringe72 #c1 a low reading voltmeter2 #d1 suitable prods1 and #e1 a thermometer4 ,ques4 ,what precaution should be taken in charging a battery8 ,ans4 ,care should be taken not to have a naked flame anywhere in its vicinity4 ,to either charge or discharge a battery at too rapid a rate involves the generation of heat4 ,thus1 while this is not liable to result in a flame under usual conditions1 the battery may take fire1 if it be improperly connected or improperly used4 ,ques4 ,what is the effect of varying the charging current8 ,ans4 ,in charging a storage cell1 particularly for the first time1 a weaker current than that specified may be used with the same result1 provided the prescribed duration of the charge be proportionally lengthened4 ,the battery may also be occasionally charged beyond the prescribed voltage1 ten or twenty per cent4 overcharge effecting no injury1 although if frequently repeated1 it shortens the life of the battery4 ,ques4 ,what are the charge indications8 ,ans4 ,the state of the charge is not only indicated by the density of the electrolyte and the voltage of the cell1 but also by the color of the plates1 which is considered by many authorities as one of the best tests for ascertaining the condition of a battery4 ,illustration3 ,,figs4 #a1aba and #a1abb4--,two methods of charging from a direct current lighting system4 ,the simplest method of charging is from an incandescent light circuit1 using lamps connected in parallel to reduce the voltage to that of the battery1 the current being adjusted by varying the number of lamps in circuit4 ,the group of lamps is in series with the battery to be charged1 and the combination is connected across the circuit furnishing the current4 ,if the charging source be a #aaj-abj volt circuit1 and the rate required be #f amperes1 twelve #af c4 p4 or six #cb c4 p4 lamps1 in parallel1 and the group in series with the battery1 will give the desired charging rate1 unless high efficiency lamps be used1 when more will be required4 ,in case a lower charging rate1 say #b amperes be used1 then a proportionately fewer number of lamps will be needed2 but the length of time required to complete the charge will be correspondingly increased4 ,instead of lamps1 as in fig4 #a1aba1 a rheostat is sometimes used1 as shown in fig #a1abb4 ,its resistance should be such as to produce1 when carrying the normal charging current1 a drop in volts equal to the difference between the pressure of the charging source and that of the battery to be charged2 thus1 if a battery of three cells1 giving #f volts1 is to be charged from a #aaj volt circuit at a #f ampere rate1 the resistance would be1 according to ,ohm's law1 7#aaj - #f7 #f #ag4c ohms4 ,the carrying capacity of the rheostat should be slightly in excess of the current required for charging4 ,an ammeter with suitable scale should be inserted in the battery circuit to indicate the current4 ,for charging more than one battery at a time from a #aaj volt circuit1 the batteries should be connected in series 7positive terminal of one battery to the negative of the next1 and so on74 ,the charging rate should be that of the battery with the lowest rate4 ,the resistance to be inserted will be less than if only one battery is being charged2 where lamp resistance is used1 this means more lamps in parallel4 ,care should be taken to remove each battery from the circuit as it becomes charged1 inserting additional resistance to take its place4 ,ques4 ,what are the colors of the plates8 ,ans4 ,in the case of formed plates1 and before the first charging1 the positives are of a dark brown color with whitish or reddish gray spots1 and the negatives are of a yellowish gray4 ,the whitish or reddish gray spots on the positive plates are small particles of lead sulphate which have not been reduced to lead peroxide during the process of forming1 and represent imperfect sulphation4 ,as a general rule1 the first charging should be carried on until these spots completely disappear4 ,after this the positive plates should be of a dark red or chocolate color at the end of the discharge1 and of a wet slate or nearly black color when fully charged4 ,a very small discharge is sufficient1 however1 to change them from black to the dark red or chocolate color4 ,if the battery has been discharged to a pressure lower than #a4h volts1 the white sulphate deposits will reappear1 turning the dark red color to a grayish tint in patches or all over the face of the plate1 or in the form of scales of a venetian red color4 ,the formation of these scales while charging indicates that the maximum charging current is too large and should be reduced until the scales or white deposits fall off or disappear1 after which the current can be increased again4 ,during charging1 the yellowish gray color of the negatives changes to a pale slate color which grows slightly darker at the completion of the charge4 ,the color of the negatives always remains1 however1 much lighter than that of the positives4 ,ques4 ,how are the best results obtained in charging8 ,ans4 ,the rate of charge should be normal1 except in cases of emergency4 ,at such a rate1 unless the constant voltage method be employed1 the cell may be considered full when the voltmeter reads #b4e volts during charge4 ,the electrolyte should be kept at uniform density throughout the cell2 when water is added1 because of evaporation1 it should be added by means of a funnel reaching to the bottom of the cell4 ,care should be taken never to add acid after evaporation2 otherwise the electrolyte will be too heavy4 ,hydrometer readings should be taken regularly2 the reading is an excellent indication of the amount of charge in the battery4 ,hydrometer readings are useless1 however1 unless the precaution be taken to keep the electrolyte of uniform density4 ,ques4 ,what voltage should be used in charging8 ,ans4 ,at the beginning of the charge the voltage should be about #e per cent4 higher than the normal voltage of the battery1 unless the latter has been overdischarged1 in which case the difference of pressure should not exceed #b per cent41 otherwise the current might be too large4 ,illustration3 ,,fig4 #a1abb4--;,diagram showing charging connections for ,exide duplex sparking battery4 ,c1 charging source2 ,d1 double pole single throw switch2 ,e1 single pole single throw switch2 ,m1 lamp resistance main battery2 ,r1 lamp resistance reserve battery4 ,ques4 ,in what two ways may batteries be charged8 ,ans4 ,they may be charged either at constant current or at constant voltage4 ,although the latter method is considered the better one by many authorities1 it is a fact1 nevertheless1 that if the charging current be normal at the beginning of the charge1 and no means be provided for keeping it constant1 it will diminish as the charging progresses1 thereby greatly increasing the length of the time required for charging1 and resulting in serious injury to the plates4 ,ques4 ,how may the charging current be kept constant8 ,ans4 ,its voltage should be gradually increased1 first to about #aj or #ae per cent4 above the voltage of the battery1 and kept at that point nearly to the end of the charge1 where in consequence of the rapid rise of pressure in the battery it might become necessary to increase the voltage of the current to #cj or #dj per cent4 above the normal of the battery4 ,illustration3 ,,figs4 #a1abd to #a1abf4--;,electric ,storage ,battery ,co4 chloride cells4 ,the voltage of cells of all capacities is slightly above #b volts on open circuit1 and during discharge at the #h hour rate it varies from that point at the beginning to #a4ge volts at the end4 ,ques4 ,what tests should be made while charging8 ,ans4 ,occasional voltage and cadmium readings of each cell should be taken for the purpose of ascertaining their condition and the behavior of the separate plates4 ,ques4 ,what tests should be made after charging8 ,ans4 ,each cell should be tested with a low reading voltmeter and hydrometer about once a week4 ,if any cell read low1 it should be cut out and examined to see if any material has been introduced which would cause a short circuit4 ,if this trouble do not exist1 the cell should be given an independent charge4 ,charge ,indications4--,the state of the charge is not only indicated by the density of the electrolyte and the voltage of the cell1 but also by the color of the plates1 which is considered by many authorities as one of the best tests for ascertaining the condition of a battery4 ,in the case of formed plates1 and before the first charging1 the positives are of a dark brown color with whitish or reddish gray spots and the negatives are of a yellowish gray4 ,the whitish or reddish gray spots on the positive plates are small particles of lead sulphate which have not been reduced to lead peroxide during the process of forming1 and represent imperfect sulphation4 ,as a general rule the first charging should be carried on until these spots completely disappear4 ,after this1 the positive plates should be of a dark red or chocolate color at the end of a discharge and of a wet slate or nearly black color when fully charged4 ,a very small discharge is sufficient1 however1 to change them from black to the dark red or chocolate color4 ,if the battery has been discharged to a pressure lower than #a4h volts1 the white sulphate deposits will reappear turning the dark red color to a grayish tint in patches or all over the surface of the plate1 or in the form of scales of a venetian red color4 ,the formation of these scales during charging indicates that the maximum charging current is too large and should be reduced until the scales or white deposits fall off or disappear1 after which the current can be increased again4 ,ques4 ,describe the behavior of the electrolyte during discharge4 ,ans4 ,there is a definite change in the density of the electrolyte for a given amount of discharge4 ,the density of the electrolyte is1 therefore1 one of the best indications of the state of charge1 provided1 of course1 no internal discharge due to local action takes place4 ,if1 when the cell is charged1 it show a density of #a4bjj1 and when discharged #a4acj1 the difference 4#jg represents the total charge4 ,if at any time the density be #a4afe1 then just one half the amount of capacity has been taken from the cell4 ,it is necessary to stir the electrolyte well1 in order for these observations to be reliable4 ,if the discharge has taken place at a high rate1 the cell must stand for an hour or more before the electrolyte will completely diffuse so that the density readings are correct4 ,illustration3 ,,fig4 #a1abg4--;,electric ,storage ,battery ,co41 arc lead burning outfit4 ,in assembling a storage battery element1 a negative plate is laid down with a separator on it1 then a positive plate1 separator1 negative plate1 etc4 ,the plates are so placed that all the lugs of the positive plates are on one side and all the lugs of the negative plates are on the other side4 ,a strip1 consisting of flat strips of lead or lead alloy1 having rectangular openings in it of the same dimensions as the cross section of the lug of the plates1 these openings being spaced to register with the lugs1 is then placed over the plate lugs of the positive plates and a similar strap is placed over the lugs of the negative plates4 ,the lugs are then burned into integral union with the straps4 ,ques4 ,define the term boiling4 ,ans4 ,boiling means the rapid evolution of gas when a cell is nearly charged4 ,ques4 ,what causes boiling8 ,ans4 ,the amount of sulphate to be converted into peroxide becomes less and less as the charge progresses and the plates therefore become virtually smaller1 so that the current becomes too large for the work demanded of it4 ,the result is1 that part of the current not actually used in the formation of peroxide decomposes the electrolyte into its constituent elements4 ,ques4 ,why do the gases evolved produce a less milky appearance of the electrolyte when a battery has been in use for a considerable time8 ,ans4 ,the plates are better formed2 consequently a larger charging current can be used without producing boiling4 ,illustration3 ,,fig4 #a1abh4--;,hydrogen gas generator for lead burning4 ,a complete lead burning outfit consists of the following parts3 #a1 hydrogen gas generator2 #b1 trap for cleaning the gas and for preventing the flame getting back in the generator2 #c1 air pump2 #d1 air tank2 #e1 blow pipe2 #f1 lead burner's mixing tee2 #g1 length of #aej feet #e_/af inch soft rubber tubing4 ,when the generator is to be used for lead burning1 connect up the different parts of the apparatus as shown4 ,fill the trap full with water and be sure to connect the gas generator to the nipple on the bottle marked ,b4 ,the stop cocks ,n and ,c must be closed4 ,see that the rubber plug at ,d is secured in place4 ,put the required amount of zinc in the opening at ,h4 7,no4 #a generator requires3 #ae lbs4 zinc1 #i gals1 water1 #c gal4 vitriol4 ,no4 #b generator requires3 #bj lbs4 zinc1 #ae gals4 water1 #e gals4 vitriol74 ,after putting in the zinc1 add the water and then the sulphuric acid1 and note that the water must always be put in before the acid4 ,when making the connection be sure that there are no low points in the hose between ,e and ,n1 as water is liable to accumulate at these low places1 which will make the gas damp which is detrimental to the burning4 ,if water get into the line1 kink the hose between ,f and ,b1 detach the hose at ,e and blow out the water with air by opening the cocks1 ,n1 ,c and ,v4 ,the length of the hose between ,t and ,x must not be longer than five feet as the cocks ,n and ,c must always be within the reach of the man who is using the flame4 ,when ready to use the flame1 open ,n which allows the hydrogen gas to escape4 ,light the same with a match and adjust the air cock ,c until the desired flame is obtained4 ,different classes of work require different flames1 which can be obtained by changing the tips and by varying the amount of gas and air with the cocks ,n and ,c4 ,when the generator is laid up for the night1 or when the charge is exhausted1 pull the hose off at ,f and draw off the solution by removing the plug at ,d4 ,the generator should then be thoroughly washed by pouring water in ,a4 ,ques4 ,what may be said of charging a battery as quickly as possible8 ,ans4 ,as a general rule1 such a procedure should not be adopted unless the battery be thoroughly discharged4 ,ques4 ,what precaution should be taken8 ,ans4 ,the danger to be avoided in rapidly charging a cell is its tendency to heat4 ,ques4 ,what apparatus is necessary in charging a battery8 ,ans4 ,the battery may be charged from direct current mains having the proper voltage4 ,a current as near uniform as possible is required1 and existing conditions must be met in each separate case4 ,sometimes a motor dynamo set with a regulating switchboard is used4 ,such an apparatus consists of a direct current dynamo1 driven direct from the shaft of a motor1 which1 in turn1 is energized by current from the line circuit4 ,with a direct current on the line1 a direct current dynamo may be used2 but with an alternating current an induction motor is required4 ,the speed of the motor is governed by a rheostat1 and the output of the dynamo is thus regulated as desired4 ,charging ,through the ,night4--,if an electric vehicle1 after a late evening run1 is to be used in the morning1 the battery may be charged during the night without an attendant being present2 but in doing this great care must be taken not to excessively overcharge4 ,a careful estimate of the amount of current required should be made and the rate of charge based on this estimate4 ,if1 say1 #gb ampere hours be required to recharge1 and the time available is nine hours1 the average rate of charge must be #h amperes4 ,if charging from a #aaj-volt circuit1 the rate at the start should be about #aj amperes2 if from a #ejj-volt circuit1 about #i amperes2 as1 in charging from a source with constant voltage1 such as a lightning or trolley circuit1 the rate into the battery will fall as the charge progresses4 ,this also applies if the charging be done from a mercury arc rectifier without attendance4 ,ques4 ,what precautions should be taken in charging a battery out of a vehicle8 ,illustration3 ,,fig4 #a1abi4--;,interior view ,northwestern storage battery4 ,the positive plate is of double grid construction1 and the negative plate consists of a special staggered grid4 ,the separators used between the plates are hard rubber1 ribbed on one side so as to prevent the positive plate from buckling4 ,it is perforated so as to allow a free circulation of the electrolyte and to decrease the internal resistance4 ,rubber separators are better than the commonly used wood or paper separators because they prevent local action4 ,the flat side of each separator is placed against a positive plate1 preventing shedding or jolting of the active material of the plate4 ,this checks deterioration4 ,the jars are made of rubber composition2 the walls are thick and the covers well fitted to avoid spilling the electrolyte4 ,all ,northwestern batteries are contained in rubber composition jars4 ,the walls are thick and the covers fit tightly to prevent spilling the acid4 ,a hard wood box1 treated with a moisture repellant is used for the outer case4 ,these batteries are made in any voltage desired1 the ampere capacity ranging from #be amp4 hrs4 to #cjj amp4 hrs4 ,ans4 ,when a battery is being overhauled1 the cells must be connected together in series and to the charging source in relatively the same manner as if they were in the vehicle2 that is1 the positive 77 terminal of one group of cells must be connected to the negative 7-7 terminal of the next group1 and the two free terminals1 one positive and the other negative1 must be connected respectively to the positive and negative terminals of the charging circuit1 but not until all of the groups have been connected in series4 ,great care must always be taken to have the polarities correct and the wire or cable for the connections of ample size to carry1 without heating1 the heaviest current used in charging4 ,charging ,small ,cells4--,for cells of the portable type1 having capacities from #aj to #ajj ampere hours1 the normal charging and discharging rate should be about one-tenth the stated capacity1 but the discharging rate may be increased to double this value1 in case of necessity4 ,if the cells be provided with formed plates and not charged1 the jars should be filled with the proper electrolyte1 and then charged for at least #aj hours steady1 or until they boil1 then they may be discharged4 ,in the case of unformed plates1 the charging should be from #cj to #dj hours1 until the cells boil1 and the plates assume their proper color4 ,ques4 ,how are small cells easily charged from #aaj or #bbj volt circuits8 ,ans4 ,this may be conveniently done by inserting in one of the charging leads an incandescent lamp which will pass the required quantity of current4 ,if the current required be as large as #aj amperes1 a suitable resistance or #aj lamps in parallel1 each passing one ampere1 may be used4 ,great care should be taken to see that the battery is connected properly4 ,period of ,charging a ,new ,battery4--,in the case of batteries provided with formed plates1 the first charge should extend over a period of not less than #cj consecutive hours1 without stopping1 if possible1 or for periods of not less than #aj hours a day for three consecutive days4 ,the electrolyte will then commence to boil or gas1 assuming a milky appearance due to the ascending bubbles of gas4 ,at this stage the density of the electrolyte as shown by the hydrometer placed in each cell should be at least #a4bjj2 it is essential that the charging should be continued until every cell boils equally4 ,from this point the charging should be prolonged until the pressure1 as determined by a voltmeter or a cadmium tester1 rises to about #b4ee volts4 ,illustration3 ,,fig4 #a1acj4--,the ,willard underslung battery box for automobiles4 ,the general tendency in automobile design1 is to keep everything off the running board as far as possible1 and to get tool boxes1 battery boxes1 etc41 placed somewhere under cover4 ,to meet these conditions the box here illustrated is arranged so that it can be underslung beneath the rear footboard or supported on auxiliary cross members made of strap iron and attached to the side members of the chassis4 ,it is usually suspended under the rear footboard or the rear seat4 ,the box has a chemically treated wood lining to make it acid proof4 ,the lining is so made that there is air space between the battery and the sides of the box1 except at the corners4 ,ventilation is thus obtained and the battery kept dry4 ,accumulation of water or spilled electrolyte in the bottom of the box is prevented by grooves in the bottom board1 extending downward from the corners to an outlet at the center of the board4 ,the box is also fitted with rubber bushings in the holes where wire leaves the battery box4 ,the charging of unformed plates is similar in all respects to that of formed plates1 except that the first charging should extend over a period of at least #gj consecutive hours without stopping1 at the end of which time the plates should have the characteristic colors of those of a fully charged battery4 ,if they do not1 the charging should be prolonged and the cell tested for density of electrolyte1 and voltage1 as already described until the desired conditions are attained4 ,then the battery may be discharged and recharged4 ,it is probable that a total of #cjj to #djj hours of charging with intervening discharges will be required to form the plates until they acquire a good color1 and the density of the electrolyte becomes stable4 ,in regular charging1 the rate should be rapid when the battery is nearly exhausted1 but it should be greatly reduced at the end of the charge after passing the point of boiling4 ,charging at too low a rate is always injurious4 ,ques4 ,what may be said with respect to the capacity of a new battery8 ,ans4 ,a new battery will never give its full capacity till after about twenty discharges4 ,during this time it should be given about #be overcharge4 ,after that1 #aj overcharge1 that is1 #aj more charge than was taken out1 will be sufficient for ordinary work4 ,high ,charging ,rates4--,occasionally it is desirable to charge a battery as quickly as possible4 ,as a general rule1 such a procedure should not be adopted unless the battery be thoroughly discharged1 and not then1 unless done by a person who thoroughly understands what he is about2 battery makers will always furnish data and directions to meet emergencies4 ,in charging a battery at a high rate1 the danger to be avoided is the tendency of the cells to heat4 ,the troubles that might arise from this cause may be prevented by immediately reducing the current strength4 ,the proper rate of charge for a given battery of cells may be thus discovered by experiment4 ,a battery should never be charged at a high rate unless it be completely exhausted1 since it is a fact that the rate of charge that it will absorb is dependent upon the amount of energy already absorbed4 ,illustration3 ,,fig4 #a1aca4--;,instructions for taking voltage readings 7,national batteries74 ,the batteries are made up of several cells1 usually two or three1 each cell representing approximately #b volts when battery is on open circuit 7neither charging nor discharging74 ,it is sometimes advisable to take individual readings of the cells1 both to determine on charge if all the cells be evenly charged1 and also on discharge to be sure that the cells are evenly discharged4 ,to do this1 a low-reading voltmeter must be used with prods attached to the voltmeter leads that can be forced into the terminals so as to insure good contacts4 ,to test the positive end cell1 put the positive prod on the positive terminal of the battery and the negative prod into small hole back of positive terminal in hard rubber cover4 ,middle cell 7in #f volt1 type ,y batteries7 is tested by inserting the positive prod in the small hole back of the positive terminal1 and the negative prod in small hole back of negative terminal4 ,in the #abj ampere hour1 ,auto type of battery1 the middle cell is tested by inserting the positive prod in the small hole back of the positive terminal and the negative prod on the middle terminal4 ,the negative end cell is tested by putting the negative prod on the negative terminal and the positive in the small hole in rubber cover back of the negative terminal4 ,a charging cell at end of charge should read about #b4ee volts4 ,a fully charged cell on open circuit should read about #b4a volts4 ,since open circuit readings vary under different conditions1 as to age1 acid1 etc41 little significance should be attached to them4 ,a discharged cell voltage will vary considerably with the many different coils1 engines1 etc41 but in the majority of cases should read between #a4h to #a4i volts1 while motor is in operation4 ,for rapid charging1 when a battery has to be charged in four hours1 the current should vary about as follows3 #dj per cent4 of total #ast hour #be #bnd #bj #crd #ae #dth ,for quick charging in three hours the rates should be3 #ej per cent4 #ast hour2 #cc per cent4 #bnd hour2 #af per cent4 #crd hour4 ,mercury ,arc ,rectifier4--,this is a device for obtaining direct current from alternating current for use in charging storage batteries4 ,the transformation is obtained at a low cost1 because the regulation is obtained from the alternating side of the rectifier1 while the current comes from the direct current side4 ,illustration3 ,,figs4 #a1acb to #a1acd4--,mercury arc rectifier outfit1 or charging set4 ,the cuts show front1 rear1 and side views of the rectifier1 illustrating the arrangement on a panel1 of the rectifier tube with its connection and operating devices4 ,the theory is as follows3 ,in an exhaust tube having one or more mercury electrodes1 ionized vapor is supplied by the negative electrode or cathode1 when the latter is in a state of excitation4 ,this condition of excitation can be kept up only as long as there is current flowing toward the negative electrode4 ,if the direction of the voltage be reversed1 so that the formerly negative electrode is now positive1 the current ceases to flow1 since in order to flow in the opposite direction it would require the formation of a new negative electrode1 which can be accomplished only by special means4 ,therefore1 the current is always flowing toward one electrode--the cathode1 which is kept excited by the current itself4 ,such a tube would cease to operate on alternating current voltage after half a cycle if some means were not provided to maintain a flow of current continuously towards the negative electrode4 ,illustration3 ,,fig4 #a1ace4--;,elementary diagram of mercury arc rectifier connections4 ,a1 ,a1 graphite anodes2 ,b1 mercury cathode2 ,c1 small starting electrode2 ,d1 battery connection2 ,e1 and ,f reactance coils2 ,g and ,h1 transformer terminals2 ,j1 battery4 ,ques4 ,describe the construction and operation of a mercury arc rectifier4 ,ans4 ,fig4 #a1ace is an elementary diagram of connections4 ,the rectifier tube in an exhausted glass vessel in which are two graphite anodes ,a1 ,a1 and one mercury cathode ,b4 ,the small starting electrode ,c is connected to one side of the alternating circuit1 through resistance2 and by rocking the tube a slight arc is formed1 which starts the operation of the rectifier tube4 ,at the instant the terminal ,h of the supply transformer is positive1 the anode ,a is then positive1 and the arc is free to flow between ,a and ,b4 ,following the direction of the arrow still further1 the current passes through the battery ,j1 through one-half of the main reactance coil ,e1 and back to the negative terminal ,g of the transformer4 ,when the impressed voltage falls below a value sufficient to maintain the arc against the reverse voltage of the arc and load1 the reactance ,e1 which heretofore has been charging1 now discharges1 the discharge current being in the same direction as formerly4 ,this serves to maintain the arc in the rectifier tube until the voltage of the supply has passed through zero1 reversed1 and built up such a value as to cause the anode ,a to have a sufficiently positive value to start the arc between it and the cathode ,b4 ,the discharge circuit of the reactance coil ,e is now through the arc ,a',b instead of through its former circuit4 ,consequently the arc ,a',b is now supplied with current1 partly from the transformer1 and partly from the reactance coil ,e4 ,the new circuit from the transformer is indicated by the arrows enclosed in circles4 ,ques4 ,how is a mercury arc rectifier started8 ,ans4 ,a rectifier outfit with its starting devices1 etc41 is shown in figs4 #a1acb to #a1acd4 ,to start the rectifier1 close in order named line switch and circuit breaker2 hold the starting switch in opposite position from normal2 rock the tube gently by rectifier shaker4 ,when the tube starts1 as shown by greenish blue light1 release starting switch and see that it goes back to normal position4 ,adjust the charging current by means of fine regulation switch on the left2 or1 if not sufficient1 by one button of coarse regulation switch on the right4 ,the regulating switch may have to be adjusted occasionally during charge1 if it be desired to maintain the charging current approximately constant4 ,capacity4--,the unit of capacity of a storage cell is the ampere hour1 that is1 the ability to discharge one ampere continuously for one hour4 ,for instance1 a #ajj ampere hour battery will give a continuous discharge of #ab amperes for eight hours4 ,it should theoretically give a discharge of #be amperes continuously for four hours1 or #ej amperes for two hours1 but in reality1 the ampere hour capacity decreases with an increase of discharge rate4 ,it requires1 theoretically 4#ace ounces of metallic lead on either element reduced to sponge lead or to lead peroxide to produce one ampere hour2 in practice1 from four to six times this amount is required4 ,the reason for this is because it is impossible to reduce all the active material1 to bring every particle in contact with the electrolyte1 or to cause every part to be penetrated by the current4 ,experiments show that from 4#e to 4#h ounces of sponge lead1 and from 4#ec to 4#hf ounces of metallic lead converted into peroxide1 are required on their respective elements to produce a discharge of one ampere hour at ordinary commercial rates4 ,the capacity increases with the temperature1 being about one per cent4 for each degree ,fahr4 increase in temperature4 ,battery capacity depends on the size and number of plates2 the quantity of active material present1 and the quantity of electrolyte4 ,for an eight hour rate of discharge and #fj degrees temperature1 the capacity of ,american batteries varies from #dj to #fj ampere hours per square foot of positive plate surface 7 #b number of positive plates in parallel length breadth74 ,the following table gives the variation of capacity for different rates of discharge3 ,capacity ,variation for ,different ,discharge ,rates ---------------------------------------- ------------------------- ,discharge ,per cent of capacity rate at #h hour rate ---------------------------------------- ------------------------- ,plante ,faure #h hour #ajj #ajj #f hour #if #if #d hour #hj #hh #b hour #fa #gj #a hour #ef #dh ---------------------------------------- ---------------------- ,illustration3 ,,fig4 #a1acf4--;,exide connector puller for removing connectors4 ,ques4 ,how may the capacity of a battery be increased8 ,ans4 ,by mixing organic materials with the lead oxide1 but any such mixture is always accompanied by a rapid deterioration of the plates4 ,discharging4--,in discharging a battery its voltage should never be allowed to fall below #a4h volts1 under load1 thus leaving about #cj per cent4 of the total capacity unused4 ,the normal discharging current may be equal to the normal charging current1 but a discharge equal to #c or #d times the normal may be given without injury to the plates4 ,some types may be discharged at even six or seven times the normal rate4 ,in such cases1 however1 the capacity will be reduced in the same proportion1 as before explained in the paragraph dealing with battery capacities4 ,illustration3 ,,figs4 #a1acg to #a1aea4--,parts of the ,witherbee battery4 #a1 jar2 #b1 inside cover2 #c1 cover2 #d1 handle2 #e1 vent cap2 #f1 cover1 screws1 nuts and washers2 #g1 handle eyes1 nuts and washers2 #h1 rubber covered nut2 #i1 spannernut2 #aj1 plate strap for positive plates2 #aa1 plate strap for negative plates2 #ab1 rubber separator2 #ac1 wood separator2 #ad1 positive group of plates2 #ae1 negative group of plates2 #af1 positive plate2 #ag1 negative plate2 #ah1 cell connector4 ,an element consists of a complete set of plates bound together on strap1 with wood and rubber separators for a single cell4 ,positive plates are brown1 negative plates1 gray4 ,ques4 ,what is the effect of discharging too rapidly8 ,ans4 ,it tends to break the plates1 and in the case of pasted plates1 a very sudden discharge will dislodge the paste4 ,ques4 ,how is the discharge capacity of a storage battery stated8 ,ans4 ,in ampere hours4 ,this1 unless otherwise specified1 refers to its output of current at the eight hour rate4 ,most manufacturers of automobile batteries specify only the amperage of the discharge at three and four hours4 ,thus1 at the eight hour rate1 a cell which will discharge at ten amperes for eight hours is said to have a capacity of eighty ampere hours4 ,it does not follow that eighty amperes would be secured if the cell were discharged in one hour4 ,it is safe to say that not more than forty amperes would be the result with this rapid discharge4 ,as a general rule1 the one hour discharge rate is four times that of the normal1 or eight hour discharge1 and considerations of economy and prudence suggest that it should never be exceeded1 if1 indeed1 it ever be employed4 ,the three hour discharge1 which is normally twice that of the eight hour1 is usually the highest that is prudent1 while the four hour discharge is the one most often employed in vehicles for the average high speed riding4 ,ques4 ,what should be the maximum rate of discharge8 ,ans4 ,the one-hour rate2 this when used1 should not extend over fifteen or twenty minutes4 ,in the case of regulating batteries a forty-five minute rate of discharge may be allowed for one or two minutes during great fluctuations of load4 ,ques4 ,how does the capacity decrease8 ,ans4 ,it decreases with the increase in current output4 ,an #hj ampere hour cell1 capable of delivering #aj amperes for #h hours1 would1 when discharged at #ad amperes1 have a capacity of #gj ampere hours2 when discharged at #bj1 its capacity would be #fj2 and when discharged at #dj1 its capacity will have decreased from #hj to #dj ampere hours4 ,illustration3 ,,fig4 #a1aeb4--,the ,edison alternating current rectifier4 ,it consists of an electro-mechanically operated valve which allows current waves of only one polarity to pass through it from the alternating current circuit to the battery which is to be charged4 ,an indicating snap switch of the usual form controls the starting and stopping of the charging current4 ,the rectifier gives any desired charging rate within its capacity4 ,the illustration shows the rectifier connected up and charging an ignition battery of five ,edison cells4 ,the connections consist of the usual connecting cord and plug and a charging lead running from the plus side of the charging terminals on the rectifier to the plus pole of the battery1 and another lead connecting the negative terminals as shown4 ,in turning the snap switch to the on position1 the proper charging current will flow into the battery4 ,when charging is completed1 the switch is turned to the off position and the battery leads disconnected4 ,ques4 ,what1 in general1 are the indications of the quantity of electricity remaining within a cell8 ,ans4 ,the voltage1 and the density of the electrolyte4 ,ques4 ,what should be done after discharging8 ,ans4 ,whenever possible the battery should be immediately charged4 ,the ,battery ,room4--,precautions should be taken to prevent any direct sunlight falling on the battery cells in glass jars1 as the breakage of such jars due to unequal expansion of the different portions of the glass1 is a source of constant trouble and danger4 ,illustration3 ,,fig4 #a1aec4--,permanent connections for ,edison rectifier4 ,as shown1 the rectifier is connected to a small switch and cutout4 ,the exclusion of direct sunlight also tends to keep the evaporation of the electrolyte at a minimum4 ,illustration3 ,,fig4 #a1aed4--;,edison ,alternating ,current rectifier2 view with cover open showing parts4 ,b1 primary circuit cord2 ,c1 condenser2 ,e1 primary relay2 ,f1 secondary switch2 ,s1 alternating circuit switch2 ,t1 transformer4 ,illustration3 ,,fig4 #a1aee4--,vibrating unit of ,edison alternating current rectifier4 ,m1 permanent magnet2 ,n1 carbon vibrating contact2 ,o1 comb radiator2 ,p1 primary circuit coil2 ,q1 vibrator adjustment screw4 ,operation of ,edison ,rectifier ,the operation of the ,edison rectifier may be explained as follows with the aid of figs4 #a1aed to #a1aef 7the parts being uniformly lettered in the figures73 ,the primary circuit taken from the alternating current mains by the cord ,b1 embraces the primary winding of the transformer ,t1 a condenser ,c1 and the coils ,p1 of the vibrating units1 fig4 #a1aee4 ,the secondary circuit from the transformer embraces the massive carbon and copper contacts 7,n and ,o1 fig4 #a1aef7 which pass only the positive waves of the alternating current1 for charging batteries or other duty4 ,an ammeter and rheostat may be placed in this charging circuit if the current is to be varied1 or a fixed connection may be substituted on the base of the rectifier if it is to be used for the maximum duty of #h or #af amperes4 ,the vibrating unit 7fig4 #a1aee71 which operates in a manner similar to the well known action of a polarized relay1 includes a permanent magnet ,m2 the coil in the primary circuit ,p2 the vibrating armature of steel with removable carbon contact ,n2 the stationary copper contact with comb top for heat radiation ,o1 and the screw ,q for adjusting the amplitude of the armature vibration4 ,the vibrating armature of each unit is divided into two parts1 which gives flexibility1 affords increased current capacity and minimizes sparking1 the two leads shown being connected together in one circuit4 ,a primary relay and a secondary switch 7,e and ,f1 figs4 #a1aed and #a1aef71 close their contacts when current is flowing4 ,upon failure of the main alternating current line they operate to open the charging circuit4 ,a storage battery is thus prevented discharging through the rectifier4 ,upon resumption of the main alternating current1 the rectifier starts automatically4 ,illustration3 ,,fig4 #a1aef4--;,elementary diagram of connections4 ,every battery room should be provided with a water tap and sink4 ,the floor should be paved with vitrified brick1 preferably blue or yellow in color1 of diamond pattern and sloping in all directions toward suitable drains4 ,a floor of this type can be easily washed by flooding with water1 and its patterns tend to keep it dry under foot at all times4 ,wooden floors are rotted very quickly by acid spillings and by the spray4 ,the room should be kept absolutely clear of everything1 which may be injured1 by the sulphuric acid fumes and it should be well ventilated to insure the safety and good health of the attendants4 ,a battery1 even at rest1 gives off hydrogen which when diluted with air forms a mixture which is very liable to explode if brought in contact with any kind of flame4 ,unless proper ventilation be provided1 the breaking of the connection when a current is flowing1 or the lighting of a bare flame lamp in the battery room would be dangerous4 ,battery ,attendants and ,workmen4--,those employed in setting up batteries are liable to suffer from soreness of hands and the destruction of clothing unless proper precautions be taken to prevent the same4 ,in order to avoid these troubles1 the boots should be painted with paraffine mixed with an equal quantity of beeswax4 ,the clothing should be of woolen material1 which1 unlike cotton1 is practically unaffected by the acid4 ,if cotton shirts be worn1 they should be dipped in a strong solution of washing soda and then rough dried4 ,an apron of sacking1 backed with flannel should be worn over all the other clothes4 ,a bottle of strong ammonia should be kept in the battery room at all times1 and in case of an accidental splash of acid on the clothes1 the immediate application of a small quantity of the ammonia1 by means of the stopper1 will at once neutralize the acid and prevent it burning a hole in the material4 ,a pail containing water made strongly alkaline with washing soda should also be kept conveniently at hand during all operations in the battery room4 ,the hands should be dipped occasionally in this water in order to prevent the skin smarting and becoming sore under the action of the acid4 ,illustration3 ,,fig4 #a1aeg4--;,interior of storage battery room showing arrangement of cells4 ,a1 are the cell insulators2 ,b1 wooden stringers2 ,c1 supporting pieces4 ,if a splash of acid should happen to enter the eye1 it should be washed at once with clean water1 warm water preferably1 and then put one or two drops of olive oil into the eye4 ,if olive oil be not immediately available1 any kind of engine oil is better than none at all4 ,points on ,care and ,management4--,in setting up storage cells1 they should be placed in as few tiers as possible1 and in such a manner that the direct rays of the sun are not allowed to fall upon the cells4 ,the rays of the sun are likely to crack the glass4 ,this is probably due to the unequal expansion of the glass1 for it has been found that jars which are carefully annealed never crack in this manner4 ,of course1 the latter precaution does not apply to large batteries1 where lead lined wooden tanks or solid lead boxes are used4 ,in installing plants where expert attendance is not to be had1 it is well to place in the circuit two magnetic cut outs1 one set for maximum current1 and the other for minimum voltage1 so that the battery cannot be discharged too low4 ,ques4 ,how should the cells be placed8 ,ans4 ,they should be placed as shown in fig4 #a1aea1 on insulators ,a1 resting on wooden stringers ,b1 and supporting pieces ,c placed on the floor4 ,the insulators are usually of glass or porcelain1 which in certain patterns may be filled with oil1 to insure better insulation as shown in figs4 #a1afe and #a1aff4 ,in setting up a battery1 it should be remembered that plates deteriorate on standing exposed to the air4 ,they should1 therefore1 be unpacked and set up immediately on arrival4 ,when they are entirely connected up1 they are ready for the addition of the electrolyte1 and for the forming charge1 which they should receive immediately4 ,ques4 ,how should the wooden stringers1 shelves1 cell boards1 and trays be treated8 ,ans4 ,they should be thoroughly varnished to insure cleanliness as well as good insulation4 ,outside of each cell and close to the mouth1 melted paraffine should be applied by means of a brush1 so as to form a band about an inch wide1 for the purpose of preventing the electrolyte creeping over the top of the jar1 wetting the outside1 and thereby impairing the insulation4 ,ques4 ,what should be done to avoid waste of current by leakage8 ,ans4 ,each cell of the battery must be thoroughly insulated4 ,ques4 ,what is the effect of verdigris which forms on the terminals8 ,ans4 ,it is a poor conductor and should therefore be removed and the terminals kept bright and clean to insure the proper flow of the current4 ,illustration3 ,,fig4 #a1aeh4--;,charging ,champion battery with charging plug4 ,where direct lighting current is available1 recharging may be done by means of the charging plug4 ,first insert the plug in a regular socket4 ,then screw a #ej c4p4 lamp into the plug and turn on4 ,to tell the positive from the negative1 lay both wires on a small piece of red litmus or test paper moistened4 ,the negative wire makes a mark on the paper4 ,this wire must go to the negative post of battery4 ,this will fully charge the #f-be-;,g battery in #ae to #bj hours4 ,ques4 ,what precautions should be taken in unpacking cells8 ,ans4 ,the plates should be handled carefully4 ,when they are sent out from the factory already built into sections1 they should be unpacked without disturbing a single plate4 ,in all cases1 every particle of packing1 straw1 hay and any chips and bits of parts should be carefully removed1 and all the dust should be blown out of the spaces between the plates by means of a bellows or other similar device4 ,,note4--,champion directions for repairs4 ,to replace broken jars in a battery remove the lid and lift out elements bodily4 ,empty the good jars with a syringe or by tilting the battery over4 ,never put the acid in any vessel except glass1 stone or lead4 ,put new jars in place same as others and run melted paraffine around the edges4 ,the wax must be broken off the elements that are to go into new jars and be poured on again4 ,fill the jars with acid to from tops4 ,melt the broken wax in a tin ladle and pour over the acid about thick4 ,do not fill with wax to tops of jars4 ,when the wax gets cold it will be found to have shrunk away from the edges of the jars4 ,fill up the opening with a little melted paraffine wax by means of a squirt can4 ,cut a small hole in the middle of the wax seal for a vent4 ,smear the brass posts and terminals and inside of case with vaseline to prevent creeping of the acid4 ,the #f-be-;,g requires one-half gallon of acid and the #f-ej-;,g one gallon4 ,although such particles are good non-conductors1 the action of the sulphuric acid electrolyte carbonizes them1 giving them conducting properties which tend to produce leakage4 ,illustration3 ,,figs4 #a1aei to #a1afa4--;,champion electric light equipment designed especially for use on launches1 yachts1 and country residences4 ,the outfit consists of three essential parts3 #a1 a dynamo run by belt from main engine2 #b1 a storage battery1 and #c1 a switchboard to regulate1 measure and control the current4 ,ques4 ,how should the cells be assembled8 ,ans4 ,in placing the plates or plate sections in the containing jars or tanks1 care should be taken to see that the supporting frame of paraffined wood bears evenly on the bottom of the jar4 ,if they do not1 wedges of paraffined wood should be placed under the frame1 so as to distribute the weight of the section equally4 ,each section should be lowered gently into the jar until it rests fairly upon the frame1 and care should be taken to see that none of the plates have shifted1 and that the section is situated centrally in the jar1 with a small clear space all around4 ,ques4 ,how should the cells be arranged8 ,ans4 ,they should be so placed that the battery attendant can see the edges of the plates and consequently the spaces between them at the same time4 ,ques4 ,describe the method of connecting the cells4 ,ans4 ,this is accomplished by means of solder1 bolts and nuts1 or clamps1 according to circumstances4 ,the use of solder is not essential if there be a good surface of the lead strip of one cell in contact with that of the next1 and provided these contact surfaces have been well cleaned4 ,usually1 the ends of the lead strips are turned up so that the junction of two cells takes the form of an inverted ,t as shown in fig4 #a1afb4 ,illustration3 ,,fig4 #a1afb4--,two storage cells2 view showing the inverted ,t form of connection4 ,ques4 ,what precaution should be taken in joining the terminals of the cells8 ,ans4 ,the contact at the junctions should be very thorough1 otherwise they will become heated when a current is flowing1 and it is desirable that the connections should include as little lead strip in the circuit as possible1 thereby reducing the amount of useless resistance4 ,brass or gun metal clamps may be kept clean by brushing them over with melted paraffin after they have been screwed up tightly4 ,when thus treated they serve to indicate points of bad contact by heat1 generated at such points1 when the current is flowing1 softening the paraffin and changing its normal color4 ,vaseline and different kinds of anti-sulphuric acid varnishes1 or preparations that are not attacked by the electrolyte1 may also be used for this purpose4 ,it is a good plan to color the varnish with vermillion or lamp black and paint the positive connections red and the negative connections black1 and also other parts of the installation for distinguishing the polarities4 ,cell ,connections4--,the cells may be connected together either in series or parallel1 or in parallel-series or series-parallel combinations1 according to the requirements1 but in all cases it is best to use the simplest arrangement practicable4 ,for instance3 if the cells employed in an installation requiring #aaj volts1 have only half the capacity required1 and #ee cells give the desired voltage1 then the number of cells must be increased to #aaj1 and theoretically the required number of amperes hours at #aaj volts may be obtained in one of two ways3 #a1 by connecting the cells in pairs in parallel and then coupling the pairs together in series1 and #b1 by arranging the #aaj cells in two complete batteries of #ee cells each connected in series1 then coupling the two batteries in parallel4 ,the first method is quite impracticable1 however1 as the slightest difference between the voltages of the two cells of any pair will result in the one having the greater pressure discharging into the other1 thereby causing the entire battery to quickly deteriorate4 ,,note4--,to determine the positive wire4 ,without a voltmeter1 the positive terminal of the charging circuit can be determined by attaching a piece of clean lead to each wire which is to be connected to the battery1 and immersing them1 without touching each other1 in a glass or other insulating vessel containing water to which is added a drop or two of sulphuric acid4 ,after the current has passed through the circuit for a short time1 the positive lead will commence to discolor1 and1 if left long enough1 will turn brown4 ,bubbles will arise from the two terminals immersed1 the larger and more frequent ones being from the negative1 the smaller ones from the positive4 ,,note4--,method of disconnecting ,national cells4 ,there are two methods of disconnecting the cells employing link connectors4 ,first a inch bit or twist drill may be used1 boring down into the top of the posts about inch4 ,the link will then be loosened and can be removed4 ,this leaves the link1 as well as the post1 in good condition for reburning4 ,second the link may be cut in the center4 ,a flame should be played on the top of the post1 at the same time grasping the end of the half link firmly with pliers4 ,when the connection has become warmed 7care being taken not to melt the lead7 the half link can be twisted loose from the port4 ,new links may be used if desired in re-assembling the cells4 ,it is not necessary to remove the covers from the element1 the links may be cut in the center and the plates removed from the jars without removing the links from the ports4 ,the links can be afterwards reburned together in the center4 ,when the cells are equipped with ,t or ,l straps1 they should be cut apart with hack saw or chisel midway between the cells1 and in re-assembling1 burned together at this point4 ,battery ,troubles4--,to successfully cope with faults in storage batteries1 there are two requisites3 #a1 a thorough knowledge of the construction and principle of operation of the battery1 and #b1 a well ordered procedure in looking for the source of trouble4 ,the faults which are usually encountered by those who operate storage batteries are here given4 ,illustration3 ,,fig4 #a1afc4--;,arrangement of battery cells and stand4 ,a1 cable lugs2 ,b1 bus bars2 ,c1 glass tanks2 ,d1 plate2 ,e1 glass insulators2 ,q1 vitrified brick2 ,o1 lead washers4 ,battery cells are set up on stands2 the one shown being built for a #ajj ampere battery4 ,larger sizes would1 of course1 require heavier stands1 and if space be limited1 the cells may be set in rows1 one above the other4 ,however1 it is evidently much better to place the cells in single rows1 where they will be convenient for inspection and repairs or any work that has to be done on them4 ,there are several other ways of setting a battery1 one of which is to place the stringers on the floor1 on vitrified brick or some other insulator1 and then place trays filled with sand on the stringers1 setting the cells in the trays on glass insulators4 ,the battery room should be dry1 clean1 well ventilated and free from metal work1 also neither too hot nor too cold4 ,too high a temperature in the battery will shorten the life of the plates1 and although there is no danger of the battery freezing1 a low temperature1 while it is maintained1 reduces the capacity2 otherwise cold has no ill effect on the battery4 ,a good temperature for the battery room is about #fj ,f4 ,a damp1 dirty room is conductive to grounds and surface leakage1 and there is danger of impurities getting into the cells4 ,if the room be very damp the electrolyte may absorb enough moisture to cause the cells to overflow4 ,strong floors are necessary to support a battery1 as one of a #ajj ampere1 #abe volt capacity weighs from #ab to #ac tons4 ,a wood floor may be used1 but a cement floor is better1 and a glazed vitrified brick floor is better still4 ,wooden floors will rot quickly from the acid1 which is sure to get onto it more or less2 a cement floor will be disintegrated if too much acid get onto it4 ,this kind of floor forms a first class ground if there be any chance for one2 the glazed brick floor is not affected by the acid and is an insulator4 ,short ,circuiting4--,a form of derangement that may occasionally affect storage batteries is short circuiting4 ,it may be caused by some of the active material--if the cell be of the pasted variety--scaling off and dropping between the plates1 or by an over collection of sediment in the bottom of the cell4 ,should the operator suspect trouble with his battery he may discover a short circuited cell by the marked difference in color of the plates or of the specific gravity of the electrolyte1 as compared with the other cells4 ,no particular damage will be caused1 if the trouble be discovered and removed before these symptoms become too marked4 ,if a foreign substance has become lodged between the plates1 it may be removed by a wood or glass instrument4 ,if some of the active material has scaled off1 it may be forced down to the bottom of the jar4 ,if excessive sediment be found1 the jar and plates should be washed carefully1 and reassembled4 ,a cell that has been short circuited may be disconnected from the battery and charged and discharged several times separately which may remedy the trouble4 ,ques4 ,how are internal short circuits indicated8 ,ans4 ,short circuits in a cell are indicated by short capacity1 low voltage and low specific gravity1 excessive heating and evaporation of the electrolyte4 ,ques4 ,how are internal short circuits located8 ,ans4 ,if the trouble cannot be located by the eye1 the battery should be connected in series and discharged at the normal rate through suitable resistance4 ,if a suitable rheostat be not available1 a water resistance may be used4 ,this consists of a receptacle 7which must not be of metal7 filled with very weak acid solution1 or with salt water in which are suspended two metal plates1 which are connected by wires through an ammeter4 ,the current may be regulated by altering the distance between the plates1 or by varying the strength of the solution4 ,as the discharge progresses the voltage will gradually decrease1 and it should be frequently read at the battery terminals2 as soon as it shows a sudden drop1 the voltage of each cell should be read with a low reading voltmeter4 ,while the readings are being taken1 the discharge rate should be kept constant and the discharge continued until the majority of the cells read #a4gj volts2 those reading less should be noted4 ,the discharge should be followed by a charge until the cells which read #a4gj volts are up1 then the low cells should be cut out1 examined1 and the trouble remedied4 ,overdischarge3 ,buckling4--,on account of unequal expansion of the two sides of a plate1 or certain portions thereof1 the strains thus set up may distort it and cause it to assume a buckled shape1 that is1 bent so one side is concave4 ,illustration3 ,,fig4 #a1afd4--,method of straightening a buckled plate4 ,buckling is caused by the unequal expansion of the plates which is due to the sulphate lodging on the plates1 thus preventing action taking place at that point2 and by excessive charging4 ,if the plates be not badly buckled1 they can be placed between #b boards and with a little pressure1 can be straightened out4 ,buckling is due always to over discharge on either the whole1 or some portion of the plate4 ,occasional buckling may occur with too rapid charge and discharge4 ,sulphation of ,plates4--,during discharge a storage cell deteriorates on account of the formation of lead sulphate over the surface of the plates4 ,this lead sulphate is the product of the chemical combination of active material with the electrolyte4 ,it is a non-conductor1 white in color and of greater volume1 in proportion than the active material4 ,when the discharge is over prolonged1 sulphation is evidenced by the electrodes becoming lighter in color1 because of the sulphate which lessens the active surface4 ,illustration3 ,,figs4 #a1afe and #a1aff4--,oil ,insulator2 fig4 #a1afe1 general view2 fig4 #a1aff1 sectional view4 ,whenever a number of open cells are in use1 unless precautions be taken1 electrical leakage between the cells invariably occurs4 ,this leakage is due chiefly to the semi-conducting nature of the thin layer of moisture which frequently covers not only the glass containing cells1 but the unimmersed parts of the elements1 and even the shelves on which the cells rest4 ,to prevent this waste of energy1 the outside of the cells should occasionally be well cleaned and thoroughly dried4 ,a little vaseline or tallow may then be rubbed over them to advantage4 ,the shelves or supports for the cells1 should either be well varnished or coated with paraffin wax4 ,electrical leakage is greatly reduced if each cell be mounted on a glass or earthenware insulator1 as shown in the illustrations4 ,the insulator here shown is in two parts and of a mushroom shape4 ,the lower cup contains a small quantity of some non-evaporating oil1 and as the conducted moisture cannot bridge across this1 a nearly perfect insulating medium is obtained4 ,these insulators are made in various sizes and may be obtained in earthenware or glass4 ,those made of glass are found to give the best results4 ,ques4 ,name some causes of sulphation4 ,ans4 ,it is sometimes caused by a too weak or too strong acid solution1 but more generally by continued over discharging1 or too rapid discharging of the batteries1 or by allowing them to remain uncharged for long periods of time4 ,ques4 ,what is the effect of sulphation8 ,ans4 ,it tends to cause shedding of the active material1 buckling of plates1 loss of capacity1 increase of resistance and consequent reduction of efficiency1 and increase of temperature with flow of current4 ,a sufficient amount of lead peroxide and sponge lead must be retained on the plates to reduce this resistance1 otherwise the charging current cannot flow through the active material and regenerate the battery4 ,illustration3 ,,fig4 #a1afg4--;,illustrating method of placing plates in glass jars4 ,ques4 ,what should be done in case of sulphation8 ,ans4 ,charge the battery below the maximum rate1 necessarily prolonging the charge1 until the plates assume the proper color4 ,this is a tedious task1 but it must not be hastened1 as rapid charging will cause serious buckling4 99 99 99 99 99 ,,note4--,how to destroy acid vapor in storage battery rooms3 ,the best remedy is a good system of thorough and rapid ventilation2 failing this the evil effect of the acid may be minimized by the fumes of a powerful alkali such as ammonia1 which will readily combine with the sulphuric acid to form sulphate of ammonia1 an inert and harmless salt4 ,if the use of liquid ammonia be objectionable1 the granulated carbonate of ammonia will do equally well4 ,the ammonia fumes are best obtained by placing dilute ammonia in shallow dishes1 so that an extensive evaporating surface is obtained4 ,in the same way the corroding dew which is so frequently deposited on the lugs and connectors of storage battery elements may readily be neutralized by the application of a solution of ammonia1 or even common washing soda4 ,a good method of protecting metal work in battery rooms is to smear it over evenly with vaseline4 ,the charging should be done at low rates4 ,discharge should not be carried below #a4h volts per cell1 and the charging current should be stopped when each cell shows #b4d volts4 ,if the plates be in a very bad condition1 a little of the white sulphate deposit on each of the positive plates may be removed with a stick1 thus exposing a part of the good surface to the action of the electrolyte4 ,if the positive plates cannot be restored to their proper color as directed1 it is cheaper to replace them by a new set1 rather than to attempt their recovery by means of reversals4 ,electrical ,data on ,national ,cells 7,size of plate #d #h7 ,number of ,plates per cell #e #g #i #aa ---------------------------------------- ---------------------------------------- ---------------------------------------- -------------- for #d hours #ab #ah #bd #cj ,discharge in amperes for #e hours #aj #ae #bj #be for #f hours #i #ac #ah #bc at #d hour rate#dh #gb #if #abj ,ampere hour capacity at #e hour rate#ea #gf #ajb #abg at #f hour rate#ee #hc #aaj #ach ,outside measurements of rubber ,length #a #b #c #d-c_/af jar1 in inches ,width #e-e_/af #e-e_/af #e-e_/af #e-e_/af ,height#aa #aa #aa #aa ,weight of cell complete1 in lbs #ad #ai #bd #bi ,weight of electrolyte1 in lbs #a #b #c #e ---------------------------------------- ---------------------------------------- ---------------------------------------- -------------- ,lack of ,capacity4--,this is usually due to the clogging of the pores in the plate with sulphate which is invisible because the surface of the plate is maintained in proper condition but the interior portions of the active material have not been thoroughly reduced4 ,to correct this condition1 the battery should be given a prolonged overcharge at low current rates1 say about one fourth the normal #h hour charging rate4 ,,note4--,oxide of lead1 litharge1 or plumbic oxide is sometimes found native as lead ochre1 and may be artificially made by heating the carbonate or nitrate4 ,it is usually prepared on a larger scale by heating the lead in air4 ,when the metal is only moderately heated1 the oxide forms a yellow powder which is known as massicot1 but at a higher temperature the oxide melts1 and on cooling1 it forms a brownish scaly mass1 which is called flake litharge4 ,the scaly pieces are afterwards ground between stones under water1 forming buff or levegated litharge4 ,the litharge of commerce often has a reddish yellow color1 due to the presence of some of the red oxide of lead1 and frequently from one to three per cent4 of finely divided metallic lead is found mixed with it4 ,when heated to dull redness litharge assumes a dark brown color1 and becomes yellow again on cooling4 ,at a bright red heat it fuses and readily attacks clay crucibles1 forming silicate of lead4 ,litharge is a most powerful base1 and has a strong tendency to form basic salts4 ,hot solution of alkalies1 as potash or soda1 readily dissolve it1 and on cooling1 it crystalizes out in the form of beautiful pink crystals4 ,falling off in the capacity may be caused by a dry cell1 due to a leaking jar2 some or all of the cells may be in a state of incomplete charge1 due to the battery having been run too low and not sufficiently charged2 or the plates may be short circuited1 either by the sediment 7deposit in the bottom of the jar7 getting up to the bottom of the plates or by something that has fallen into the cell4 ,electrical ,data on ,american ,cells ---------------------------------------- ---------------------------------------- --------------------- ,normal ,number of #cj volt ,tungsten lamps that can ,capacity be run with #af cells in series for #b1 #d1 #f or #h hours ---------------------------------------- ---------------------------------------- ---------------- ,ampere hours #b hours #d hours #f hours #h hours #dj #ad #i #h #g #fj #ag #ad #ab #aj #hj #bh #ah #ae #ad #abj #db #bg #bd #ba #afj #eg #cg #ca #bh #bjj #ga #de #dj #ce #bej #hh #ef #ej #dd #cjj #ajf #gj #fj #eb #cej #abd #ha #ga #fb #djj #adb #ia #ha #ga ---------------------------------------- ---------------------------------------- ---------------- ,illustration3 ,,fig4 #a1afh4--;,american cell4 ,ques4 ,what action takes place when a battery stands idle for some time8 ,ans4 ,it loses part of its charge1 due to local losses in the cells4 ,ques4 ,how should batteries be treated1 when used but occasionally8 ,ans4 ,if a battery is not to be used for several days1 it should first be fully charged before standing2 if it continue idle1 a freshening charge should be given every two weeks1 continuing the charge when the cells begin to gas freely4 ,ques4 ,what should be done in case of lack of capacity8 ,ans4 ,if the current consumption be normal1 there may be poor connections or trouble in the battery2 there may be a dry cell1 due to a leaking jar2 some or all of the cells may be in a state of incomplete charge1 due to the battery having been run too low and not sufficiently charged1 or the plates may be short circuited1 either by the sediment 7deposit in the bottom of the jar7 getting up to the bottom of the plates or by something that has fallen into the cell4 ,electrical ,data on ,autex ,cells 7,standard plates2 size1 #e x #h7 ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,number of ,plates #g #i #aa #ac ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,discharge in ,amperes for #d hours #ba #bh #ce #db ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,length #b #c #d #e ,outside ,measurements -------------------------------- ,width #f #f #f #f ,rubber ,jars in inches4 -------------------------------- ,height #ab #ab #ab #ab ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,element #ae #bj #bd #bi ---------------------------------------- ------------------------ ,weight in ,pounds ,electrolyte #d #e #e #f ---------------------------------------- ------------------------ ,complete ,cell #bb #bh #cd #dj ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,electrical ,data on ,autex ,cells7continued7 7,standard plates2 size1 #e x #h7 ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,number of ,plates #ae #ag #ai #ba ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,discharge in ,amperes for #d hours #di #ef #fc #gj ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,length #e #f #g #h ,outside ,measurements ---------------------------------------- ------------------------ ,width #f #f #f #f ,rubber ,jars in inches4 ---------------------------------------- ------------------------ ,height #ab #ab #ab #ab ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,element #cd #ch #dc #dg ---------------------------------------- ------------------------ ,weight in ,pounds ,electrolyte #g #g #h #i ---------------------------------------- ------------------------ ,complete ,cell #dg #ec #ei #ff ---------------------------------------- ---------------------------------------- ---------------------------------------- -------- ,,note4--,peroxide of lead1 pure oxide or plumbic dioxide is the true active material in all forms of lead storage cell4 ,this lead salt is found native as the mineral plattnerite4 ,it is a heavy lead ore1 forming black1 lustrous1 six sided prisms4 ,it may be prepared from the red oxide by boiling it in fine powder1 with nitric acid diluted with five parts of water1 or by treating the carbonate when suspended in water with a stream of chlorine gas1 and then thoroughly washing and drying it4 ,it is reduced to a lower oxide on heating or by exposure to bright sunlight4 ,this salt readily imparts oxygen to other substances2 it becomes heated to redness when thrown into sulphuric dioxide1 and takes fire when triturated with sulphur--hence this oxide is a common ingredient in lucifer match composition4 ,when used in primary or secondary batteries it readily imparts its oxygen to nascent hydrogen1 forming water1 and thus it acts as a powerful depolarizer4 ,when robbed of its oxygen1 it readily becomes reoxidized1 if subjected to the action of nascent oxygen liberated by the electrolytic decomposition of water4 ,if the trouble cannot be located by the eye1 connect the battery in series1 and discharge it at the normal rate1 through suitable resistance4 ,if a suitable rheostat be not available1 a water resistance may be used4 ,this consists of a receptacle 7which must not be of metal7 filled with very weak acid solution or salt water in which are suspended two metal plates1 which are connected1 by wires through an ammeter4 ,electrical ,data on ,autex ,cells 7,light weight plates2 size1 #e #h7 ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ,number of ,plates #g #i #aa #ac #ae ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ,discharge in ,amperes for #e hours #ae #ba #bf #ca #cf ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ,outside ,length #a-bi_/cb #b-g_/af #c-ca_/cb #c #d-cb ,measurements ---------------------------------------- ---------------------------------------- ---------- ,width #f #f #f #f #f ,rubber ---------------------------------------- ---------------------------------------- ---------- ,jars in in4 ,height #ab #ab #ab #ab #ab ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ,weight ,element #aa #ad #ah #ba #bd in ---------------------------------------- ---------------------------------------- ---------- ,pounds ,electrolyte #b #b #c #c #d ---------------------------------------- ---------------------------------------- ---------- ,comp4 ,cell #ae #bj #bd #bh #cc ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ,number of ,plates #ag #ai #ba #bc #be ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ,discharge in ,amperes for #e hours #db #dg #eb #eg #fc ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ,outside ,length #d-i_/af #e-c_/cb #e #f-e_/cb #f-aa_/af ,measurements ---------------------------------------- ---------------------------------------- ---------- ,width #f #f #f #f #f ,rubber ---------------------------------------- ---------------------------------------- ---------- ,jars in in4,height #ab #ab #ab #ab #ab ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ,weight ,element #bg #ca #cd #cg #dj in ---------------------------------------- ---------------------------------------- ---------- ,pounds ,electrolyte #d #e #f #f #g ---------------------------------------- ---------------------------------------- ---------- ,comp4 ,cell #ch #db #df #ea #ef ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------- ,the current may be regulated by altering the distance between the plates or by varying the strength of the solution4 ,as the discharge progresses1 the voltage will gradually decrease and it should be frequently read at the battery terminals4 ,when it shows a sudden drop1 the voltage of each cell should be read with a low reading voltmeter4 ,while the readings are being taken1 the discharge rate should be kept constant and the discharge continued until the majority of the cells read #a4gj volts2 those reading less should be noted4 ,the discharge should be followed by a charge until the cells which read #a4gj volts are up2 then the low cells should be cut out1 examined and the trouble remedied4 ,,note4--,how to prevent lead poisoning4 ,workmen employed in the manufacture of lead or lead salts are always liable to lead poisoning1 both by inhaling the dust and by contact of the materials with the hands4 ,various preventives for this have been employed1 and of these1 the most simple seems to be a careful washing of the hands in petroleum4 ,it is said that three washings a day are sufficient to prevent all serious danger of poisoning4 ,the benzole in the petroleum appears to scour the skin and remove the loose lead dust1 and the fatty substance in the oil fills up the pores of the skin and prevents the absorption of the deleterious salts4 ,the employment of petroleum has given such good results that it has been proposed to use this material as a guard against poisoning in other industries where the salts of copper or mercury are employed4 ,ques4 ,what causes low specific gravity when there are no short circuits8 ,ans4 #a1 sloppage or a leaky jar 7the loss having been replaced with water alone71 #b1 insufficient charge1 #c1 over discharge1 or #d1 a combination of these abuses4 ,any of these mean that there is acid in combination with the plates4 ,in this case the acid should be brought out into the electrolyte by a long charge at a quarter of the normal discharge rate4 ,illustration3 ,,figs4 #a1afi and #a1agj4--,the ,national storage battery2 views showing methods of assembling cells4 ,fig #a1afi1 end assembling2 fig #a1agj1 side assembling4 ,ques4 ,how should weak cells be treated8 ,ans4 ,they should be grouped by themselves and charged as a separate battery1 care being taken that the positive strap of one cell1 is connected to the negative strap of the adjoining cell and that the charging connections are properly made4 ,if there be not sufficient resistance in the charging rheostat to reduce the current to the proper point1 a water resistance should be used4 ,,note4--,pole testing paper4 ,make a thin solution of white starch and soak strips of thin white blotting paper in it1 and set aside in a clean1 dry place to dry4 ,dissolve oz4 of potassium iodide in one pint of water4 ,immerse the strips in the solution for a few seconds and again dry4 ,this paper1 when moistened and used in the usual way1 turns violet at the positive pole4 ,while a cell is being treated1 when possible1 the cover should be removed 7if sealed1 the compound can be loosened by using a hot putty knife74 ,illustration3 ,,figs4 #a1aga to #a1agg4--,national battery bolt connector and parts4 ,the connector is equipped with grease cups and antimonious lead washers4 ,disconnecting ,cells4--,the best method of disconnecting cells assembled with pillar straps1 for the purpose of replacing broken jars1 cleaning or taking out of commission1 is to use a five-eighth inch twist drill1 in a carpenter's brace1 boring down into the top of the pillar about one-quarter inch2 then pull off the connector sleeve from the pillar4 ,by following this method1 all parts may be used again4 ,when cells are equipped with top straps1 the straps should be cut with a sharp knife or chisel midway between the cells4 ,taking ,batteries out of ,commission4--,where a battery is to be out of service for several months1 and it is not convenient to give it the freshening charge every two weeks1 it should be taken out of commission4 ,,comparison ,,of ,,the ,,baum ,,and ,,specific ,,gravity ,,scales ,,at #fj ,,fahrenheit ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------------- ,degrees,specific,degrees,specific,degre es,specific,degrees,specific ,baume ,gravity ,baume ,gravity ,baume ,gravity ,baume ,gravity ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------------- #j #a4jjj #ag #a4acc #cd #a4cjf #ea #a4edb #a #a4jjg #ah #a4adb #ce #a4cah #eb #a4eei #b #a4jad #ai #a4aea #cf #a4ccj #ec #a4egf #c #a4jba #bj #a4afj #cg #a4cdb #ed #a4eic #d #a4jbh #ba #a4afi #ch #a4cee #ee #a4faa #e #a4jcf #bb #a4agi #ci #a4cfh #ef #a4fbi #f #a4jdc #bc #a4ahh #dj #a4cha #eg #a4fdh #g #a4jea #bd #a4aih #da #a4cid #eh #a4fff #h #a4jeh #be #a4bjh #db #a4djh #ei #a4fhf #i #a4jff #bf #a4bah #dc #a4dba #fj #a4gjg #aj #a4jgd #bg #a4bbi #dd #a4dcf #fa #a4gbf #aa #a4jhb #bh #a4bci #de #a4dej #fb #a4gdg #ab #a4jij #bi #a4bej #df #a4dfe #fc #a4gfh #ac #a4jih #cj #a4bfa #dg #a4dgi #fd #a4gij #ad #a4ajg #ca #a4bgb #dh #a4die #fe #a4hab #ae #a4aae #cb #a4bhc #di #a4eaj #ff #a4hce #af #a4abd #cc #a4bie #ej #a4ebf ---------------------------------------- ---------------------------------------- ---------------------------------------- ---------------------------- ,,note4--,the characteristic properties of concentrated sulphuric acid are very marked4 ,its freedom from odor1 oily appearance1 and its great weight1 distinguish it from other liquids4 ,the pure concentrated commercial acid has a density which usually reaches #a4hdb1 and its boiling point is about #fdj ,f4 ,the absolutely pure acid is perfectly colorless1 but usually even that used in laboratories has a peculiar grayish color1 due to slight traces of organic matter4 ,sulphuric acid is exceedingly hydroscopic1 and when exposed to the air it rapidly increases in bulk1 owing to absorption of atmospheric moisture4 ,,note4--,clamps not made of metal similar to that of the connecting strips1 frequently give trouble from the galvanic action due to the contact of dissimilar metals in the presence of moisture which causes the destruction of either the connecting strip or the clamp4 ,such troubles can be avoided by placing a thin strip of sheet zinc between the lead strip and the clamp4 ,under these circumstances the zinc will crumble away1 and can be replaced without much inconvenience and very little expense1 while the clamps and connecting strips will remain uninjured4 ,strength of ,dilute ,sulphuric ,acid of ,different ,densities at #ei ,fahr4 ---------------------------------------- ---------------------------------------- ------------------------ ,per cent4 ,specific ,per cent4 ,specific of of ,sulphuric ,acid ,gravity ,sulphuric ,acid ,gravity ---------------------------------------- ---------------------------------------- ------------------------ #ajj #a4hdb #bc #a4afg #dj #a4cjf #bb #a4aei #ca #a4bca #ba #a4aea #cj #a4bbc #bj #a4add #bi #a4bae #ai #a4acf #bh #a4bjf #ah #a4abi #bg #a4aih #ag #a4aba #bf #a4aij #af #a4aaf #be #a4agb #ae #a4ajf #bd #a4agd #ad #a4jih ---------------------------------------- ---------------------------------------- ------------------------ ,ques4 ,describe the method of taking a battery out of commission4 ,ans4 ,the battery is charged in the usual manner1 until the specific gravity of the electrolyte of every cell has stopped rising over a period of one hour 7if there be any low cells1 due to short circuits or other cause1 they should be put in condition before the charge is started1 so that they will receive the full benefit of it74 ,the cells may now be disconnected and covers and elements removed from the jars1 7if sealed1 the compound is loosened with a hot putty knife74 ,the elements are placed on their sides with the plates slightly spread apart at the bottom1 the separators withdrawn1 and the positive and negative groups pulled apart4 ,the electrolyte is washed off with a gentle stream of water and the plates allowed to drain and dry4#g ,the positive plates are ready to be put away4 ,when dry1 the negatives are completely immersed in electrolyte 7of about #a4bge specific gravity71 and allowed to soak for three or four hours4 ,the jars may be used for this purpose4 ,after rinsing and drying1 they are ready to be put away2 wash also the rubber separators4 #g ,,note4--,if the active material in the negative plates extend beyond the ribs of the grid 7the supporting frame71 it should be at once pressed back into place1 care being taken to prevent the plates drying before this is done4 ,the most suitable and convenient method for pressing1 is to place between the plates smooth boards of a thickness equal to the distance between the plates and then put the groups under pressure4 ,wood separators1 after having been in service1 will not stand much handling and had better be thrown away4 ,if it be thought worth while to keep them1 they must be immersed in water or weak electrolyte1 and in re-assembling1 the electrolyte must be put into the cells immediately1 as wet wood separators must not stand exposed to the air4 ,illustration3 ,,fig4 #a1agh4--,the ,witham charging board1 for charging from any electric outlet on a direct current system4 ,the instrument shows the direction of the current1 and the candle power of the lamps used as resistance indicates approximately the strength of the current passing4 ,operation3 ,from any convenient electric light fitting remove one of the lamps1 replacing it by the plug attached to the flexible cord4 ,screw the lamp into one of the sockets on the charging board4 ,connect a wire to each binding post1 and before joining up to the battery1 hold the ends of the two wires together4 ,the lamp will then light up and the indicator needle will point to that binding post which must be connected to the positive 77 terminal of the battery4 ,the other binding post must1 of course1 be connected to the negative 7-7 of the battery4 ,the charging current can be increased by inserting another lamp into the second socket on the charging board and by using lamps of higher candle power4 ,if1 when the lamp lights up1 the indicator needle do not point to one of the binding posts1 but retain its position midway1 then the current is an alternating one and will not charge the battery4 ,ques4 ,what precaution should be taken with the jars8 ,ans4 ,they should be thoroughly cleaned with fresh water1 no sediment being allowed to remain4 ,putting ,batteries into ,commission4--,when re-assembling a battery1 it should be treated in the same manner as if it were new and the regular instructions for assembling and putting a new battery into commission followed4 ,cleaning ,jars4--,the jars should be thoroughly cleaned with fresh water1 no sediment being allowed to remain4 ,table of ,voltage ,change as ,affected by ,discharge ,rate#h #h ,,note4--,the voltage increase or decrease with change in current is practically constant in a given type of cell for any size of cell when the current is referred to a given time rate of charge or discharge2 that is1 the drop in a large cell or in a small cell1 when each is discharged at its four1 six or eight hour rate1 will be the same4 ,the drop varies somewhat for the condition of the battery charge4 ,for batteries which are one-third discharged1 the temperature #fj ,fahr41 and plates in good condition1 the changes in pressure which may be expected between open circuit voltage and the voltage on charge or discharge are given in the above table4 #h hour rate 4#je volt #f 4#jfe #d 4#ji #c 4#aa #b 4#ad #a 4#ah #a 4#ba ,condensed ,rules for the ,proper ,care of ,batteries4--,the following general instructions should be followed in the care and maintenance of batteries3 #a4 ,a battery must always be charged with direct current and in the right direction4 #b4 ,be careful to charge at the proper rates and to give the right amount of charge2 do not undercharge or overcharge to an excessive degree4 #c4 ,do not bring a naked flame near the battery while charging or immediately afterwards4 #d4 ,do not overdischarge4 #e4 ,do not allow the battery to stand completely discharged4 #f4 ,voltage readings should be taken only when the battery is charging or discharging2 if taken when the battery is standing idle they are of little or no value4 #g4 ,do not allow the battery temperature to exceed #aaj ,fahr4 #h4 ,keep the electrolyte at the proper height above the top of the plates and at the proper specific gravity4 ,use only pure water to replace loss by evaporation4 ,in preparing the electrolyte never pour water into the acid4 #i4 ,keep the cells free from dirt and all foreign substances1 both solid and liquid4 #aj4 ,keep the battery and all connections clean2 keep all bolted connections tight4 #aa4 ,if there be lack of capacity in a battery1 due to low cells1 do not delay in locating and bringing them back to condition4 #ab4 ,do not allow sediment to get up to the plates4 ,,chapter ,,xlv ,,storage ,,battery ,,systems ,storage batteries are used for many purposes1 such as to supply current for electric vehicles1 gas engine ignition1 lighting1 and in connection with power stations and distribution work4 99 99 99 99 99 ,the latter is an important field1 the storage battery being used in connection with the power station for the following purposes3 #a4 ,to carry the peak load1 during hours of maximum demand2 #b4 ,to carry the entire load during hours of minimum demand1 or for a short time in case of emergency2 #c4 ,to act as an equalizer2 #d4 ,for regulation of load and voltage2 #e4 ,as compensation for feeder drop2 #f4 ,as a preventive against shut downs4 ,in almost every electric lighting plant there are long periods during the day and late at night when the number of lamps lighted is so small that it may not pay to run the generating machinery4 ,in such cases1 storage batteries may usually be used to advantage to aid in carrying the maximum load and to supply the entire current at minimum load as illustrated in fig4 #a1agi4 ,in other words1 batteries are substituted for a certain portion of the machinery plant or are used in place of the latter4 ,ques4 ,what provision must be made in power plants when storage batteries are not used8 ,ans4 ,the capacity of the generating machinery must be sufficient for the heaviest overloads which may occur1 and it must be operated continuously for #bd hours a day in the majority of central stations supplying current for lighting and power4 ,ques4 ,what results are obtained with this method of working8 ,ans4 ,the engines working under very variable loads1 not only operate at low efficiency1 but are continually subjected to severe mechanical strains4 ,illustration3 ,,fig4 #a1agi4--,load curve showing use of storage battery as an aid to the generating machinery4 ,in the diagram1 it is seen that the battery discharges at minimum and maximum loads and is charged at other times1 the battery furnishing current for the entire minimum load and part of the maximum load4 ,ques4 ,how may greater efficiency be secured with steam engines under variable loads8 ,ans4 ,judicious selection of the number and sizes of the engines enable them to be worked in most cases at a considerable fraction of their full capacity nearly all the time4 ,ques4 ,what further improvement is secured in most cases with the storage battery8 ,ans4 ,the plant is made more flexible1 and the economy of the engines is increased by making their loads nearer uniform1 and nearer to full capacity while they are running4 ,ques4 ,what is the effect of a battery connected in parallel with a dynamo1 as in fig4 #a1ahj8 ,ans4 ,it is not necessary for the dynamo to have a capacity exceeding that which is sufficient for the average daily load1 at which it may be worked practically all the time4 ,illustration3 ,,fig4 #a1ahj4--,storage battery connected in parallel with a dynamo4 ,this arrangement enables the dynamo to be stopped for a considerable portion of the time1 and thus save labor and attention4 ,it also acts to prevent fluctuations as in a dynamo driven by a gas engine whose speed varies periodically because of the nature of its cycle of operation4 ,when the load is below the average1 the dynamo charges the battery1 and when the load rises above the average1 during the hours of maximum demand1 the battery discharges into the line in parallel with the dynamo4 ,during the hours of minimum demand the engines may be shut down and the necessary current supplied from the battery alone1 thus not only increasing the efficiency of the plant1 but serving to maintain a steadier pressure under fluctuating loads4 ,ques4 ,what is understood by the expression floating the battery on the line8 ,ans4 ,a storage battery is said to float on a line when connected across the circuit at some distance from the power station1 so that a heavy load on the line1 within the range of the battery influence1 causes sufficient line drop to allow the battery to discharge1 while with a light load on the line1 the drop is small and the impressed voltage at the battery high enough to charge the battery4 ,this usage is confined chiefly to electric railway service1 where large voltage changes are permissible4 ,illustration3 ,,fig4 #a1aha4--;,diagram showing effect of storage battery in regulating the dynamo load in a combined railway and lighting plant4 ,in this case the average and line loads are about equal and the battery covers the instantaneous fluctuations4 ,it will be noted that while the line load fluctuations vary between #ghj and #a1dbj amperes1 those of the dynamo load are kept at an average between #a1jcj and #a1afj amperes4 ,ques4 ,when the battery is floated on the line1 how may the amount of charge be made to approximately equal the amount of discharge8 ,ans4 ,by properly proportioning the number of cells in series4 ,connections and ,circuit ,control ,apparatus4--,when a storage battery is used in an electric lighting plant1 provision must be made for feeding the lamps1 etc41 from either the dynamo or battery separately1 or from the two working in parallel1 and it should be possible to charge the battery at the same time the lamps are being supplied4 ,to accomplish these results requires three switches1 for the following connections3 #a4 ,to connect the lamps to the dynamo2 #b4 ,to connect the lamps to the battery2 #c4 ,to connect the battery to the dynamo4 ,illustration3 ,,fig4 #a1ahb4--;,diagram showing action of storage battery as a reservoir of reserve power4 ,the figure shows an actual load curve from an ,edison station for #bd hours4 ,a sudden storm caused the load to be thrown on very quickly1 the peak of the load being higher than usual4 ,in some plants1 the first switch is omitted1 because the lamps are always fed by the battery alone1 the latter being charged during the day1 when no lamps are in use4 ,it is desirable1 however1 to have all three switches in every plant in order to be able to supply lamps and charge the battery at any time4 ,in the battery circuit there should be an ammeter having a scale on both sides of zero1 to show whether the battery is being charged or discharged1 as well as the value of the current4 ,another similar ammeter is required in the circuit between the dynamo and the battery1 to show the direction and amount of current4 ,a third ammeter is desirable in the lamp circuit1 to show the total current supplied to the lamps1 but it need only indicate on one side of zero1 since the current there always flows in the same direction4 ,illustration3 ,,fig4 #a1ahc4--;,diagram showing three wire system with one dynamo and storage battery4 ,a #bbj volt dynamo charges a storage battery of corresponding pressure1 which in turn subdivides the pressure and supplies a three wire system1 the neutral wire of which is connected to the middle point of the battery as shown4 ,a voltmeter is required with a three-way switch to connect it to the dynamo1 battery or lamps1 and a circuit breaker must be inserted in the battery circuit in order that it may be opened when the current becomes excessive4 ,a discriminating cut out or reverse current circuit breaker is required between the dynamo and the battery to open the circuit when the charging current falls below a certain value1 and thus avoid any danger of the battery discharging through the dynamo1 if from any cause the voltage of the latter drop below that of the battery4 ,this completes the ordinary measuring and circuit controlling apparatus employed with storage batteries4 ,methods of ,control for ,storage ,batteries4--,as the external voltage of a storage battery varies with the amount of charge it contains and with the direction of the current1 it is necessary to employ some means for compensating this variation in order to maintain a constant voltage on the line supplied by the battery4 ,the various devices used for this purpose are as follows3 #a4 ,variable resistances2 #b4 ,end cell switches2 #c4 ,reverse pressure cells2 #d4 ,boosters4 ,illustration3 ,,fig4 #a1ahd4--;,diagram showing connections for ignition outfit4 ,the charging switch has four indications--,off1 ,battery1 ,dynamo and ,charge4 ,when engine is at rest switch is turned to ,off4 ,the first turn brings it to ,battery1 enabling the engine to be started4 ,next turn cuts battery off and puts ,dynamo direct on engine4 ,the next turn brings the switch to ,charge4 ,dynamo then charges the battery and surplus current is stored up4 ,next turn is ,off1 which stops engine and disconnects battery from dynamo4 ,test the dynamo wires with test paper 7negative makes mark74 ,put positive of dynamo to positive of battery4 ,dynamo should be regulated to charge at about four amperes4 ,the particular method selected will depend upon the size of the battery1 the purpose for which it is used1 the allowable limits pf current and voltage variations1 the cost of the system1 etc4 ,variable ,resistance4--,regulation by variable resistance may be used advantageously only with batteries of small capacity1 and in small lighting plants such as those of yachts1 where the space available for battery auxiliaries is limited1 and where the cost of energy is so low that the loss of power in the resistance is not objectionable4 ,illustration3 ,,fig4 #a1ahe4--,variable resistance method of regulation for storage battery2 diagram showing connections for charging two halves of a battery in parallel4 ,the connections for one of the simplest methods is shown in fig4 #a1ahe4 ,the battery is divided into two halves1 which are connected in series for discharging and in parallel for charging4 ,since the voltage of each cell at the end of a discharge should not be lower than #a4h volts1 a battery intended for use on a #aaj volt lighting circuit will require #aaj #a4h #fb cells4 ,the voltage necessary1 however1 for each cell at the end of a charge is about #b4f volts1 or a total of #b4f #fb #afa volts for the battery1 a value which is far above the line voltage4 ,by dividing the battery into two halves and connecting them in parallel only #hj4e volts are necessary for charging4 ,the excess voltage of the line1 #bi4e volts is taken up by the resistance1 which also controls the output of the battery on discharge4 ,end ,cell ,switches4--,these may be used to advantage in small installations where there is not demand for current during the day1 or where the charging is done by means of boosters4 ,illustration3 ,,fig4 #a1ahf4--;,diagram of connections of a battery equipment for a residential lighting plant4 ,in the diagram the voltmeter and voltmeter connections have been omitted4 ,the bus bars on the battery panel are connected directly to the bus bars on the dynamo panel4 ,in this installation the dynamos are run during the afternoon on discharge1 being regulated by means of an end cell switch4 ,on charge1 the pressure above that of the bus bars1 required to bring all cells up to full charge1 is supplied by means of a motor driven charging booster1 the voltage at the armature being suitably varied by changing the field excitation4 ,ques4 ,what is an end cell switch8 ,ans4 ,a form of switch employed in connection with a storage battery in order to control the end cells for regulating the voltage4 ,ques4 ,describe the construction of an end cell switch4 ,ans4 ,this is shown in fig4 #a1ahg4 ,the switch contact arm is made in two parts1 ,a and ,b1 which are insulated from each other as shown1 and connected with each other through the protective resistance ,r4 ,the end cell contacts are so spaced that when the main current carrying part ,a of the switch arm is squarely on one end cell contact such as ,x1 the part ,b1 does not touch any other contact such as ,y1 but when the switch arm is advanced for cutting into circuit another end cell1 the part ,b1 reaches the contact ,y before the part ,a1 leaves the contact ,x1 thus keeping the battery circuit closed1 while the resistance ,r1 limits the current in the short circuited cell at the instant the switch arm passes from one end cell contact to the next4 ,illustration3 ,,fig4 #a1ahg4--;,diagram of end cell switch4 ,this form of switch controls several cells at one end of a storage battery and is used for regulating the voltage4 ,the requirement of an end cell switch is that in switching from one end cell contact to another1 the discharging circuit must not be opened1 neither must the moving arm touch one contact before leaving the one adjacent1 since the joining of two contacts will short circuit the cells connected thereto4 ,to accomplish this1 the spacings of the two arms and contacts are such that when the main arm ,a is squarely on an end cell contact1 the advance or auxiliary arm ,b touches no other contact1 but in passing from one point to the next1 the advance arm reaches the contact toward which it is moving before the main arm leaves its contact4 ,the resistance ,x1 between the two points prevents short circuiting1 and the current to the main circuit is never broken4 ,ques4 ,how should the conductors joining the end cells to the end cell switch contacts be proportioned8 ,ans4 ,they must have the same sectional area as the conductors of the main circuit4 ,the reason for this is that when any end cell is in use1 the conductor connecting it to the switch becomes a part of the main circuit4 ,an allowance of #a1jjj amperes per sq4 in41 when the battery is discharging at the two-hour rate1 is considered good practice4 ,ques4 ,describe some of the features of end cell switch construction4 ,ans4 ,those of small capacity are made circular2 the larger sizes are made horizontal in form1 and both types may be either operated by hand or motor driven4 ,illustration3 ,,fig4 #a1ahh4--;,end cell switch control for storage battery2 connections showing main line open when the battery is being charged4 ,ques4 ,where are end cell switches of large capacity located8 ,ans4 ,generally they are placed as near the battery room as possible to avoid the cost of running the heavy conductors1 and when such switches are motor driven1 the usual practice is to control their operation from the main switchboard4 ,in fig4 #a1ahh is shown the method of regulation with an end switch4 ,the diagram shows the battery being charged with the main switch open1 and the voltage of the dynamo raised to the charging pressure4 ,during discharge the cells are connected in series1 and as the voltage of each cell at the beginning of discharge is at least #b4a volts1 only #eb or #ec cells are required to give the desired pressure of #aaj volts1 but as the discharge continues1 and the voltage of each cell decreases1 the end cells1 #a1 #b1 #c1 #d1 etc41 are cut into circuit successively by means of the end cell switch1 thereby adding to and compensating the drop in the total voltage until1 at the end of discharge when the voltage of each cell has fallen to #a4h volts1 the entire #fb cells are in series to supply the required line pressure4 ,illustration3 ,,fig4 #a1ahi4--;,diagram of connections arranged for charging battery in two parallel groups and discharging in series1 the charge and discharge being controlled by variable resistances4 ,in yacht lighting the limited space generally prohibits the use of a charging booster1 and in such instances this method of charge and discharge control is the usual practice4 ,in case the dynamo from which the battery is charged has sufficient range in voltage to charge all cells in series1 a charging booster is not required1 nor is it necessary to connect groups of cells in parallel1 as the dynamo voltage may be varied as charge proceeds4 ,for a #aaj volt circuit1 the number of cells required is #aaj #a4h #fa1 and the number in series when the battery begins to discharge is #aaj #b4a #eb4 ,hence1 in a #aaj volt circuit an arrangement must be provided whereby #fa - #eb #i cells may be cut out or switched in1 one by one4 ,the number of end cells for any voltage may be obtained by the following formula3 ,number of end cells 7,e_/#a4h7 - 7,e_/#b4a7 ,e voltage of supply circuit2 #a4h minimum voltage of cell during discharge2 #b4a voltage of fully charged cell4 ,reverse ,pressure ,cells4--,these consist of unformed lead plates immersed in the ordinary electrolyte of dilute sulphuric acid4 ,as they have no active material1 they possess no capacity1 but are capable of setting up an opposing pressure of about #b volts each to the discharging current flowing through them1 thereby cutting down the total voltage of the battery1 so that the net voltage across the line depends on the number of reverse current cells in series in the battery circuit4 ,as the voltage of the battery falls during discharge1 the reverse pressure cells are cut out1 successively1 thus keeping the external or line voltage constant4 ,illustration3 ,,fig4 #a1aij4--,regulation with reverse pressure cells4 ,these cells are merely lead plates placed in an electrolyte of dilute sulphuric acid4 ,they have no capacity but set up an opposing or reverse voltage of approximately #b volts per cell if current be passed through them4 ,in using these cells for controlling discharge1 the total number of active cells in the battery will be the same as if the method of end cell control had been used4 ,reverse pressure cells represent an increase in equipment of about #h per cent4 or more4 ,these cells1 as shown1 are connected in the circuit in opposition to the main battery1 and conductors are run from each of them to points on a switch similar to an end cell switch4 ,at the beginning of discharge1 all the reverse cells are in circuit1 acting in opposition to the main battery4 ,as discharge proceeds and the battery voltage falls1 the reverse cells are gradually cut out of circuit4 ,the only advantage in this method of regulation is that the discharge throughout the battery is uniform1 but this fact alone does not warrant such means of regulation on account of the additional expense involved1 and the energy loss when discharging against reverse cells is the same as if resistance had been placed in the circuit4 ,it is obvious1 that as these cells do not possess any capacity1 the number of active cells required in the battery will be the same as when end cell control is employed4 ,therefore1 the reverse pressure cells represent an increase in equipment1 which entails an additional expense of at least #h per cent4 ,for this reason1 and also on account of the fact that the amount of energy lost in discharging against reverse pressure cells1 is the same as when the resistance methods of controlling the discharge are employed1 the use of cells for this purpose is now practically obsolete4 ,illustration3 ,,fig4 #a1aia4--;,holzer-,cabot dynamotor 7type ,k74 ,a dynamotor is a combination of dynamo and motor on the same shaft1 one receiving current1 usually of different voltage1 the motor being employed to drive the dynamo with a pressure either higher or lower than that received at the motor terminals4 ,a machine of the dynamotor form1 with its windings exactly alike1 is often used in three wire systems to balance or equalize the two halves of the circuit as in fig4 #gih4 ,boosters4--,in general1 a booster may be defined as a dynamo inserted in series in a circuit1 to change its voltage4 ,it may be driven by an electric motor1 in which case it is sometimes called a motor-booster4 ,the function of a booster is to add to an electric pressure derived from another source4 ,for instance1 if a storage battery be used in conjunction with one or more dynamos to supply current to an electric light installation1 the battery cannot be charged from the machines which are feeding the lamps1 because it requires a pressure higher than that required for the lamps to complete the charge4 ,a small dynamo is therefore connected in series1 with the main machines and the battery1 acting in conjunction with the former to provide the necessary pressure4 ,illustration3 ,,fig4 #a1aib4--;,dayton launch lighting outfit4 ,it consists of an ,apple dynamo1 switchboard and storage battery4 ,the dynamo is fitted with a bevel friction drive governor4 ,the dynamo gives a three ampere charging rate on a six volt battery at its normal speed of #a1jej ,r4 ,p4 ,m4 ,the switchboard is provided with a combination volt-ammeter which shows the voltage of the battery1 the ampere charging rate of the dynamo and the ampere discharging rate of the battery4 ,the automatic cut out in the back of the switchboard automatically severs the connections between the dynamo and the storage battery when the engine stops and so prevents the storage battery current running back through the dynamo when the dynamo is not generating current4 ,a #f volt1 #fj ampere hour battery1 consisting of #c five plate units connected in series1 is used with the size dynamo shown in the illustration4 ,the power for running such a dynamo is obtained in various ways4 ,the dynamo or charging booster may be belt driven or arranged on an extension of the armature shaft of the main dynamo2 again1 it may consist of a single armature with a double winding 7fig4 #a1aia71 or a motor and dynamo coupled together on one bed plate as in figs4 #hjj and #hje4 ,boosters may be divided into several classes as follows3 #a4 ,series boosters2 #b4 ,shunt boosters2 #c4 ,compound boosters2 #d4 ,differential boosters2 #e4 ,constant current boosters2 #f4 ,separately excited boosters4 ,series ,boosters4--,the series booster acts so as to compound the battery1 and tends to maintain a constant voltage on the line1 whatever the load may be4 ,its operation depends on the fact that the dynamo voltage must rise and fall with the load4 ,it can1 therefore1 be used only with a shunt dynamo or its equivalent as the source of supply4 ,ques4 ,what use is made of the series booster system8 ,ans4 ,it is suited to power1 but not to incandescent lighting purposes1 being similar in operation to a floating battery4 ,it is not extensively used as the other types give better service1 under the same conditions4 ,illustration3 ,,fig4 #a1aic4--;,diagram of ,joseph ,bijur's storage battery system 7,general ,storage ,battery ,co474 ,the booster field winding has one terminal connected to the middle point of the battery and the other terminal1 to the wire joining the resistances ,a and ,b4 ,a lever1 pivoted at ,l1 carries at either end a number of contact points which dip into troughs of mercury when one end of the lever moves upward or downward4 ,these points are connected to corresponding points on their respective resistances1 and therefore all of the resistances connected to contact points which are immersed in the mercury are short circuited4 ,the points are of various lengths1 so that when the lever operates1 they contact progressively with the mercury4 ,if more of the ,a points than the ,b points be immersed in the mercury1 the resistance of ,b is less than that of ,a1 more sections of it being short circuited4 ,current will therefore flow from the middle point of the battery1 through the booster field1 and through ,b to the negative side of the system1 exciting the booster field and producing a booster voltage to charge the battery4 ,again1 if more of the ,a points be immersed1 the ,a resistance becomes the smaller1 and current then flows from the positive side of the system through resistance ,a1 through the booster field to the middle point of the battery1 the field excitation and the booster pressure produced being in a direction opposite to the first described1 and tending to discharge the battery4 ,when the resistances ,a and ,b are equal1 there is no pressure to send current in either direction through the booster field coil4 ,when the load on the external circuit is normal1 the lever is in a horizontal position1 ,a and ,b being equal1 no current flows through the booster field hence1 no current passes into or out of the battery4 ,with increase of external load1 the pull of the solenoid is strengthened by a small increase in dynamo current passing through the winding4 ,this draws down the left end of the lever producing a current in the booster field such as to discharge the battery and assist the dynamo to supply the load demand4 ,a decrease in external load is attended by a slight diminution in dynamo current1 the solenoid is weakened and the pull of the spring predominates4 ,this results in a downward movement of the right side of the lever causing excitation of the booster field to produce a pressure to send charge into the battery4 ,ques4 ,describe some characteristics of the series booster4 ,ans4 ,it is automatic and adjusts its voltage to produce the proper ratio of charge or discharge with varying external load1 and it also tends to maintain a constant voltage across the line1 under all conditions of change in circuit4 ,illustration3 ,,fig4 #a1aid4--,load diagram1 showing kind of service to which the shunt booster is adapted4 ,shunt ,boosters4--,this type of machine is simply a shunt dynamo1 having its armature circuit in series with the line from the main dynamo to the battery4 ,a rheostat controls the field excitation4 ,its function is to send charge into the battery4 ,it is used in plants where the battery is not designed to take up load fluctuations1 but is in service only to carry the peak of the load1 being charged during periods of light loads and discharged in parallel with the dynamo4 ,the shunt booster acts to increase the voltage applied to the battery so that the charging current will flow into the latter4 ,ques4 ,how is a battery used with a shunt booster proportioned8 ,ans4 ,usually sufficient battery is provided to carry the entire load during the light load period4 ,ques4 ,explain the use of the rheostat controlling the field excitation4 ,ans4 ,it is used to vary the booster voltage so as to hasten the charging of the battery if desired4 ,illustration3 ,,fig4 #a1aie4--;,entz' carbon pile booster system 7,electric ,storage ,battery ,co474 ,the booster field winding is connected at one end to the middle point of the battery4 ,the other end is connected to the upper contact points of two carbon pile resistances1 ,a and ,b4 ,the lower end of ,a is connected to the negative side of the battery1 and the corresponding end of ,b1 to the positive side4 ,this arrangement constitutes in effect a potentiometer4 ,if the resistance of ,a be equal to that of ,b1 there is no pressure in the booster field to establish current through it4 ,the drop through ,a ,b is equal to the total battery voltage1 and if ,a ,b1 the drop from either side of the battery through ,a or ,b is one-half the total drop1 hence the end of the booster field winding1 connected to the upper ends of ,a and ,b is also at the pressure of the middle point of the battery which is likewise the pressure of the other side of the booster field coil4 ,accordingly when ,a ,b1 there can be no current through the coil4 ,when the two resistances are unequal1 there will be current through the booster field1 its direction depending on which of the resistances is the less1 and its magnitude will be proportional to the difference between the two resistances4 ,variations in the pressure on a carbon pile causes variations in its resistance and the solenoid1 ,m1 opposed by spring ,s1 both pulling on lever ,l which rests on the two piles ,a and ,b1 controls the relative resistances of the two piles to cause charge and discharge of the battery4 ,the solenoid winding is in series with the dynamo circuit and when the load is normal1 the spring pull is just equal to the magnet pull1 and the resistance of ,a and ,b are equal4 ,when external load varies1 a small but proportional variation in the pull of ,p charges the relative resistances of the piles and the booster field is energized to produce a voltage to cause battery charge or discharge4 ,ques4 ,for what service is the shunt booster not suited8 ,ans4 ,it is not adapted to circuits where there are sudden fluctuations that are great compared with the capacity of the dynamo4 ,ques4 ,what is its action in changing from charge to discharge8 ,ans4 ,it is not automatic1 the switching must be done by hand4 ,illustration3 ,,fig4 #a1aif4--;,diagram showing usual connections of a non-reversible shunt booster and battery system4 ,in charging1 the switches ,a and ,b are closed1 and ,c put on contact m2 the end cell switch ,d is put on the last contact4 ,part of the dynamo current will go into the line and part through the booster into the battery4 ,the charging current is adjusted by the field rheostat ,e4 ,to discharge1 throw the end cell switch ,d to first contact2 next turn switch ,c to contact s4 ,the battery is then in parallel with the dynamo with all end cells cut out4 ,as the voltage of the battery falls1 end cells are cut in by the end cell switch ,d4 ,ques4 ,how may it be used reversibly8 ,ans4 ,it will give a pressure to assist the battery to discharge when excited from the bus bars and provided with a reversing rheostat4 ,in this case it will assist the battery to discharge when the direction of the field magnetization is changed4 ,when so used1 no end cells are necessary1 but the booster must be run continuously during the entire period of discharge4 ,ques4 ,what should be the battery capacity on a #aaj volt circuit with a reversible booster8 ,ans4 #ef cells will be sufficient4 ,the voltage to fully charge is #ef #b4f #adf1 or #cf volts above dynamo voltage4 ,minimum voltage of discharge #a4h #ef #ajj volts1 or #aj volts less than that of the line4 ,hence1 the booster need give only #cf volts maximum1 and is required to add #aj volts to the battery voltage toward the end of battery discharge4 ,in this case1 the booster voltage is only #cf_/di or about of that required in the preceding case2 five cells less of battery are necessary and the end cell switches and leads are eliminated4 ,illustration3 ,,fig4 #a1aig4--;,diagram of compound booster connections4 ,the machine will be larger1 however1 than it would be if used only for charging1 because the discharge current is unusually greater than that of charge1 and the current carrying of the armature must be great enough to take care of the heaviest currents4 ,compound ,boosters4--,these machines are used on railway and power circuits where there are great fluctuations in load1 the battery acting to prevent excessive drop and to assist the generating machinery in carrying the load1 relieving it from the strain of sudden rushes of current4 ,the connections are shown in the diagram fig4 #a1aig4 ,under ordinary working conditions1 the shunt field of the booster creates an electric pressure in the same direction as that of the battery1 tending to discharge it4 ,illustration3 ,,fig4 #a1aih4--;,fairbanks-,morse lighting outfit4 ,the above cut illustrates a #b horse power vertical special gasoline or kerosene oil engine belted to a 4#i kw4 compound wound #cb volt dynamo4 ,it will supply a maximum of #db-bj watt1 or #ej-ae watt #cb volt ,tungsten lamps and is built and balanced1 so that current can be taken direct from the dynamo without flicker in the lights4 ,the storage battery has #af cells and a capacity of #d amperes for #g hours at #cb volts4 ,this will supply seven #bj watt ,tungsten lamps for #g hours1 or nine #ae watt lamps for #g hours4 ,the switchboard is arranged so as to give #bd hours service4 ,it is customary to run the engine during most of the lighting period and to use the battery for lights late at night4 ,if the whole number of lights be not used when the engine and dynamo are in operation1 the surplus is used to charge the battery4 ,when no current is flowing into or out of the battery1 the following relation exists3 ,dynamo voltage booster voltage battery voltage ,in this case the dynamo carries the whole external load4 ,if the load increase1 the dynamo voltage decreases1 so that the booster voltage battery voltage is greater than the dynamo voltage1 and the battery begins to discharge4 ,in discharging1 the current passes through the series field of the booster and produces a proportional pressure acting with the shunt field to raise the voltage of the booster1 thus increasing the battery discharge and shifting more of the load from the dynamo1 until the system becomes balanced4 ,illustration3 ,,fig4 #a1aii4--;,diagram showing method of charging a storage battery at one voltage and supplying lights at a different voltage4 ,as may be seen1 two end cell switches are required4 ,the voltage of the supply current is adjusted by the number of cells in series on switch ,s'1 while switch ,s is moved to cut out cells as they become fully charged4 ,in this instance the end cells included between the contact arms of the two end cell switches must be of sufficient size to receive the charging current1 plus the current to the supply circuit4 ,if the battery can be charged at times when the dynamo is supplying no other load1 only one end cell switch is required4 ,if the load on the external circuit be small1 the dynamo voltage rises and current flows into the battery4 ,in this case the series field acts against the shunt field and decreases the booster voltage so that the pressure at the dynamo is greater than booster and battery voltage combined1 thus increasing the rate of charge of the battery until the load causes the dynamo voltage to drop to normal and the system is again balanced4 ,the battery and booster can be placed at the power house or where the greatest drop is likely to occur4 ,as this system1 like the series booster1 depends for its action upon the drop of voltage with increase of load1 it is only adapted to shunt wound dynamos4 ,from the foregoing description it will be seen that the compound booster is automatic within certain limits of battery charge4 ,any marked change of battery voltage will be followed by a corresponding change in dynamo current1 unless the rheostat be manipulated to bring battery voltage booster voltage back to normal4 ,while the theoretical dynamo current variation is small for a given change of load1 there is always a sudden1 momentary1 current rush from the dynamo on increase of load1 the duration of which is equal to the time lag of magnetization of the booster field4 ,lights on a circuit with variable load will wink on sudden changes of load4 ,in this respect the compound booster is not so satisfactory as the constant current booster1 as in the latter all dynamo current passes through the series fields1 which1 by reason of their self-induction1 oppose and check any sudden current rush1 giving the booster field time to change its magnetization to the proper degree4 ,illustration3 ,,fig4 #a1bjj4--;,diagram of connection of one form of differential booster4 ,in operation1 the dynamo current passes through the series winding of the booster1 and the current in this winding is to remain practically constant4 ,the shunt coil produces a field which opposes the field produced by the series coil1 the resulting magnetization being1 in direction and amount1 the resultant of the two field strengths4 ,the adjustments are so made that when the normal dynamo current is passing through the series coil1 the shunt field just neutralizes its effect1 and the resultant magnetization is zero4 ,since the open current voltage of the battery is equal to that of the system1 neither charge nor discharge takes place4 ,with increased demand on the line1 the slight increase in dynamo current in the series coil overpowers the shunt field1 and causes a pressure in the booster armature in such direction as to assist discharge4 ,if the external load fall below the average demand1 the current in the series coil decreases slightly so that the shunt field predominates1 producing a booster armature pressure in a direction to assist charge4 ,although the voltage of the battery falls while discharging by an amount proportional to the outflowing current the increased excitation due to this current through the series coil is also proportional to it1 and the booster voltage rises as that of the battery falls1 their sum being always equal to that of the system4 ,in other words1 the booster serves to compound the battery for constant pressure4 ,differential ,boosters4--,in this type of booster1 a series coil energized from the main current1 tends to discharge the battery1 and a shunt coil1 excited from the battery1 tends to charge the cells4 ,these two coils are opposed to one another1 and the difference in their respective strengths represents the net strength available for boosting4 ,in order to produce quicker reversal1 additional compound coils are sometimes added4 ,illustration3 ,,fig4 #a1bja4--;,diagram of differential booster system with compensating coil4 ,in operation1 the compensating field coil of the booster opposes the shunt coil and prevents the variation of the battery voltage disturbing the equilibrium of the system4 ,if the battery pressure be lower than normal1 it will not discharge rapidly enough to relieve the dynamo from overload fluctuations1 unless the booster voltage be increased1 and the dynamo will therefore have to supply a current greater than normal4 ,if a current greater than normal flow through the compensating coil1 the effect of the shunt coil opposed by the series coil is decreased1 and the compensating coil1 acting in the same direction as the series coil1 causes a higher booster pressure tending to discharge the battery1 and thus brings down the dynamo load to normal4 ,should the battery voltage be above its normal value1 the battery would discharge too rapidly and carry more than its share of the load4 ,in operating this system1 the varying load must be beyond the booster equipment4 ,the series and compensating coils may be temporarily short circuited so that the battery may be charged more rapidly4 ,ques4 ,for what service is the differential booster adapted8 ,ans4 ,it is suited to power and railway circuits where the load fluctuates widely and suddenly4 ,there are several varieties of this type of booster1 and many patents have been issued covering the different methods of varying the voltage of the machine4 ,constant ,current ,boosters4--,in installations where it is desired to supply both an approximately constant load and a fluctuating load from the same dynamos 7as for instance1 in office buildings or hotels1 where it is necessary to supply lights and elevators from the same source71 the fluctuations in the power circuits must not interfere with the lighting circuits and to prevent this1 two sets of bus bars are provided4 ,illustration3 ,,fig4 #a1bjb4--;,diagram of non-reversible or constant current booster system4 ,the booster armature and field are in series between one side of the lighting and power bus bars4 ,a shunt field is also provided1 which acts in opposition to the series field4 ,this booster carries a practically unvarying current from the lighting to the power bus bars1 regardless of the fluctuations of the external load1 which current is equal to the average required by the fluctuating load4 ,except under abnormal conditions the shunt field always predominates giving a voltage which is added to that of the lighting bus bars1 so that the voltage across the power busses is always higher than that across the lighting by an amount equal to the booster voltage4 ,if an excessive load come on the power circuits1 the increased excitation of the series coil1 due to a slight increase in current from the lighting to the power bus bars1 lowers the booster voltage and consequently reduces the voltage across the power bus bars4 ,the battery discharges1 furnishing an amount of current equal to the difference between that required by the load and the constant current through the booster4 ,if the power load decrease below normal1 the slight decrease in current in the booster series field increases the booster armature voltage and the excess current goes into the battery4 ,the booster1 therefore1 does not in reality give a constant current1 but by proper design the variation may be kept within a few per cent4 ,the dynamos are connected in the usual manner to one set of bus bars1 and the lighting circuits are connected across these4 ,across the other set of bars are connected the circuits supplying the fluctuating load1 and the battery is also connected directly across these power bars4 ,the power bars are supplied with current from the lighting bars1 a non-reversible or so called constant current booster being interposed between the two as shown in fig4 #a1bjb4 ,since this permits only a constant current to pass from the lighting bus bars1 the load on the dynamo does not vary1 although the load on the power busses may vary widely4 ,illustration3 ,,fig4 #a1bjc4--;,hubbard's separately excited booster system 7,gould ,storage ,battery ,co472 diagram showing general arrangement4 ,separately ,excited ,boosters4--,in some forms of booster the field excitation is secured by a small exciting dynamo4 ,an example of this class is shown in fig4 #a1bjc4 ,the exciter is provided with a single series coil1 through which the station output or a proportional part thereof passes4 ,the armature of the exciter is connected to the exciting coil on the booster1 and thence across the mains as shown4 ,,note4--,reversible boosters should be used where the average total current to the fluctuating load is greater than the battery discharge current1 and where the pressure of the power bus bars must not fall off with increase in load4 ,electric railway and lighting plants having long feeders are examples of the systems to which reversible boosters are suited4 ,non-reversible boosters should be used where the average total load is less than the battery discharge current1 and where a drop in the voltage of the power bus bars is of advantage4 ,examples of such plants are hotels or apartment houses where electric elevators are operated from the lighting dynamos4 ,boosters are usually driven by electric motors directly connected to them1 though any form of driving power may be used4 ,with the average current passing through the field coil or the exciter1 its armature generates a voltage which is equal to that of the system1 and in opposition to it4 ,these two opposing pressures balance1 and no current flows in the booster field coils4 ,illustration3 ,,fig4 #a1bjd4--;,battery system with regulation for long feeders1 for installing where it is desirable to locate the battery at a point remote from the station and avoid any equipment requiring constant attention at the battery end4 ,the compound wound motor1 constant current booster is used and keeps constant the current flowing through the feeder1 the battery taking up all load fluctuations4 ,with an increase in external load above the average1 the tendency is for an increase to take place through the exciter series coil1 augmenting its field strength and consequently the exciter armature voltage4 ,this latter now being higher than that of the line1 causes current to flow in the booster field coil in such a direction as to produce a pressure in the booster armature which assists the battery to discharge1 and is of a magnitude to compensate for the battery drop occasioned thereby4 ,illustration3 ,,fig4 #a1bje4--;,diagram illustrating storage battery system1 as applied to an automobile for lighting4 ,when the load decreases below the normal1 the current in the exciter field is decreased1 and its armature voltage falls below that of the system4 ,current will now flow in an opposite direction in the booster field coil1 generating a voltage in the booster armature to assist charge4 ,since the exciter always generates a voltage in opposition to that of the line1 this system is known commercially as the counter pressure system4 ,,hawkins ,,practical ,,library ,,of ,,electricity ,,in ,,handy ,,pocket ,,form ,,price #a4jj ,,each ,they are not only the best1 but the cheapest work published on ,electricity4 ,the books are sold at #a each4 ,each number being complete in itself4 ,they are guaranteed in every way or your money will be returned4 ,the new numbers will be supplied for #a each1 as published4 ,,now ,,ready ,,electrical ,,guide1 ,,no4 #a ,containing the principles of ,elementary ,electricity1 ,magnetism1 ,induction1 ,experiments1 ,dynamos1 ,electric ,machinery4 ,,electrical ,,guide1 ,,no4 #b ,the construction of ,dynamos1 ,motors1 ,armatures1 ,armature ,windings1 ,installing of ,dynamos4 ,,electrical ,,guide1 ,,no4 #c ,electrical ,instruments1 ,testing1 ,practical ,management of ,dynamos and ,motors4 ,,electrical ,,guide1 ,,no4 #d ,distribution ,systems1 ,wiring1 ,wiring ,diagrams1 ,sign ,flashers1 ,storage ,batteries4 ,,electrical ,,guide1 ,,no4 #e ,principles of ,alternating ,currents and ,alternators4 ,,electrical ,,guide1 ,,no4 #f ,alternating ,current ,motors1 ,transformers1 ,converters1 ,rectifiers4 ,,electrical ,,guide1 ,,no4 #g ,alternating ,current ,systems1 ,circuit ,breakers1 ,measuring ,instruments4 ,,electrical ,,guide1 ,,no4 #h ,alternating ,current ,switch ,boards1 ,wiring1 ,power ,stations1 ,installation and ,operation4 ,,in ,,work 7,ready ,soon7 ,,electrical ,,guide1 ,,no4 #i ,telephone1 ,telegraph1 ,wireless1 ,bells1 ,lighting1 ,railways4 ,,electrical ,,guide1 ,,no4 #aj ,modern ,practical ,applications of ,electricity and ,ready ,reference ,index of the #aj ,numbers4 ,theo4 ,audel ,co41 ,publishers #gb ,,fifth ,,avenue4 ,transcriber's ,note3 ,where possible1 unicode characters are used4 ,some of the fractions do not have a unicode character which will cause some inconsistencies in the display4 ,inconsistent spelling and hyphenation are as in the original4