J*3_ *V " 'A *** S^*~\ |,|6^ N ;'/<>-' -4JM *9 i NA; -^ I^?*^ V^jgSf ' A ^U^r* ^ UNIVERSAL WIRING COMPUTER FOR DETERMINING The Size of Wires for Incandescent Electric Lamp Leads AND FOR DISTRIBUTION IN GENERAL, Without Calculation, Formulas or Knowledge of Mathematics WITH SOME NOTES ON WIRING AND A SET OF AUXILIARY TABLES. BY CARL HERING NEW YOEK: THE W. J. JOHNSTON COMPANY, LTD. 1891 2- Copyright, 1891, by Carl Bering. PREFACE. IN submitting to the public the accompanying new system for determining the size of leads without calculations, the author desires to say that he has endeavored to make the charts as simple and practical as possible; but, as in other new departures, it is possible that such proportions as the dimensions of the scales, their ranges, the size of the charts, the limit of accuracy, etc., might be more advantageously chosen so as to bring the average values to the best parts of the charts. As the values for the< usual determinations have such very wide limits, it is difficult to determine on the best proportions of the charts except by long and repeated use in practice under widely differing circumstances. Since this can best be done by the aid of those using this system under different circumstances, the author appeals to those using these charts to aid him in finding the most convenient propor- tions, by suggesting to him any changes in the present proportions gained from actual experience with the charts. Such changes will, if practicable, be embodied and duly acknowledged in subse- quent editions, of which copies will be sent to those to whose kindness the author owes the changes. As its title indicates, this book is intended to facilitate the computing of the size and quantity of wire used for wiring ; it is not a treatise on wiring, but assumes a knowledge of wiring on the part of the reader. It is intended for a book of reference, and not for a book of instruction. The auxiliary tables, which were almost all calculated for this book, are limited to those which wiremen frequently have occasion to refer to. The author is indebted to his friend Richard W. Davids for some practical suggestions, and to the ELECTRICAL ENGINEER for the use of some of the illustrations. CARL HERING. Philadelphia, April, 1891. & > 7 b 8 CONTENTS. PAGE Introduction 1 Explanation of the Charts 3 Hints and Modifications 4 Charts following 8 Distribution of Incandescent Light Leads 9 Fusible Cut Outs 17 Wiring Formulae. Their Deduction and Use 18 Tables : Tables of Wire Gauges ... 23 Table of Compounded Wires of Large Cross Section 28 Table of the Weight and Eesistance of Copper Wire 30 Table of Temperature Corrections for Copper Wire 32 Weight of Insulated Wire for Wiring 33 Table of Heating Limits or Maximum Safe Carrying Capacity of Insulated Wires 34 Table of Horse Power Equivalents 35 Wiring Tables 38 UNIVERSAL WIRING COMPUTER. INTRODUCTION. THE determination of the proper size of the wire for distribut- ing current for incandescent lighting, is burdened with the use of formulae having " constants " varying with each style of lamp ; these constants mean different things, depending on which formula is used; furthermore many wiremen and contractors may not know how this constant is determined, and therefore they cannot deduce it themselves if they have forgotten it, or if they have to wire for a different make of lamp. Such formulae and constants are therefore often unsatisfactory for all cases except for daily work with one particular make of lamp. Even then there is no small amount of calculation necessary to make a proper determi- nation of the wiring of a building; the natural consequence is that much of the wiring is a mere guess as to the size of wire, and it is a matter of chance whether this guess is a good one or a bad one. The sizes of wire may be so widely different for differing conditions, that a " guess " is more likely to be a bad one, except, perhaps, in the unfrequent case of a person making very many determinations daily for the same make of lamp ; even in such cases it is well to check the results by a proper determination. The competition among contractors for wiring is getting to be so (1) ; JNTkCDUCTION. great thaV f it;^iJ2:;l>f* tttfc ,w& who makes the most economical determination of the sizes of wire, who will be able to outbid his competitors who may either waste wire in making it too large, or have to add an additional wire afterwards in case it was too small. The cause of much of this " guessing " is doubtless due to the fact that it requires no small amount of figuring to make even an approximate determination of the sizes of the wire. It is to diminish this work that the author has devised the accompanying charts, by means of which all such determinations are made at a glance, more readily even than if the values were looked up in tables (if such tables existed), which would necessarily have to be very bulky and cumbersome, in order to cover such a wide range as that required for the general practice. EXPLANATION OF THE CHARTS. GENERAL. These charts will give directly and without calcula- tion or the use of formulae, the gauge number or cross-section in circular mils of leads for any number of lamps of any make, at any distance and for any loss. There are three charts with differ- ent scales, covering the following ranges : Few lamps at short distances. Few lamps at long distances. Many lamps at short distances. Also a blank chart which can be filled out for any special ranges, as will be described below. The ranges overlap somewhat, so that if the values sought for are on awkward parts of the charts, they will probably be found in better parts on one of the other charts. They cover the ranges for house wiring, for large or small houses, and give the results with a degree of accuracy which is far greater than is necessary on account of the wide limits between the standard sizes of wire in the market ; a greater accuracy than this would be absurd, as one cannot generally obtain the wire for any but the regular sizes, and not even for all of these. For many lamps at a great distance, a small error would make a great differ- ence in the cost of the wire. For such cases the wire must be cal- culated by means of the usual formula, for which see page 19. How TO USE THE CHARTS. The vertical scale just below the center represents the current in amperes for one lamp. Find the current of the particular make of lamp on this scale, and follow it horizontally to the left until it intersects the diagonal represent- ing the desired loss in volts (see broken line on charts) ; from this intersection follow the corresponding vertical line until it inter- sects the diagonal in the upper left hand portion, representing the desired number of lamps ; from this intersection follow horizon- tally to the right to the next set of diagonals representing the dis- tances in feet (not the length and return, but merely the distance one way), and from this intersection follow down vertically to the scale which gives the circular mils, as also the B. & S. (American) (3) 4 WIRING COMPUTER. wire gauge numbers. An example is worked out on each chart and indicated on the chart by a broken line. It should be noticed that the loss is given in volts, and not in per cent., except for a 100-volt lamp, for which the loss in per cent, and in volts is the same thing. For any other voltage, if the loss is given in per cent., find the number of volts which this represents before starting to use the chart. This is done by mul- tiplying the voltage of the lamp, say 75 volts, by the per cent., say 2 per cent., and divide by 100 ; thus, 75 x 2 -r- 100 = 1.5 volts. HINTS AND MODIFICATIONS. " FOR ONE PARTICULAR MAKE OF LAMP. If, as is generally the case, a large number of determinations are to be made for one particular make of lamp, the work can be shortened considerably by laying off with care, on the first scale, the current for that lamp, and then with a lead pencil or red ink draw a bold horizontal line across to the left. The intersections of this line with the volt diagonals will then be the starting points for the different losses. The numbers which the diagonals represent can then be trans- ferred to this line for convenience. FOR ONE PARTICULAR Loss. If, besides using the same lamp the loss is also the same for a large number of determinations, which is very often the case, then draw a second red line, or bold pencil line, vertically upward across the " lamp " diagonals, then these intersections (in the upper left hand field) will be the start- ing points for all determinations, thus simplifying the work by reducing it to one-half. It is recommended in this case to transfer the numbers representing the lamps to the intersections of this new line, with the respective diagonals in that field, as these inter- sections form the starting points. STANDARD SIZES OF WIRES. The work is still further simplified by the vertical dotted lines in the right hand field which have been drawn through the gauge numbers on the scale which represent the standard B. &. S. sizes of wire. This facilitates following the vertical lines down to the scale, thus reducing the amount of work still more. Loss IN PER CENT. INSTEAD OF VOLTS. If it is preferable to have the losses read in per cent, instead of in volts, the change can be made by calculating what percentages are represented by EXPLANATION OP THE CHARTS. 5 each of the volt lines, and marking them accordingly. But such figures will be correct only for lamps of that same voltage, and for no other. INTERPOLATING. For values lying between two diagonals, or when new diagonals are drawn for special values (as, for instance, for one standard loss in volts), notice that in the lower left hand field the distances between the diagonals should be measured on a vertical scale on which they are proportional to the volts ; for instance, a diagonal representing 1 J- volt would be half way be- tween that for 1 volt and that for 1 J volt, measured on any vertical line, and not on a horizontal line nor on the arc of a circle. The same thing is true of the upper left hand field (lamps), namely, that the vertical scale is quite regular. In the upper right hand field (feet), it is the horizontal scale and not the vertical which is regular. CHANGING THE SCALES. The following points are worth re- membering. The number of lamps and the distances in feet are interchangeable. It may be^ more convenient sometimes to use lamps for feet and feet for lamps ; both give the same result. Fur- thermore, either of these two may be divided or multiplied by 2, or 10, or 100, etc., if the other one is correspondingly multiplied or divided by the same factor. For instance, 1 lamp at 400 feet is the same as 2 lamps at 200 feet, or 4 lamps at 100 feet. Some- times one or the other of these alternatives is more convenient to find. With the volt scale, however, it is different ; if the volt figures are multiplied by two, for instance, the lamp figures (or the feet) must be multiplied (not divided) by two also ; for instance, for a 1-amp. lamp and a J-volt loss, the intersection falls off the chart ; but by using the 1-volt diagonal instead, and doub- ling the number of lamps (or the feet), the final result will be the same. Such changes are rarely necessary, on account of the dif- ferent ranges of the different charts; but it may often be less trouble to take such an alternative than to turn to another chart. SPARE CHARTS. A spare chart has been added on which the lines are identical with those on the other charts. This may be filled out with figures so as to cover any special work, as, for instance, for the three- wire system, for motor work, or perhaps for improvements on the ranges of the scales of the other charts.* * See Preface. 6 WIRING COMPUTER. The two preceding paragraphs will explain in what proportions the numbers may be changed without changing the lines themselves. Spare charts may be obtained from the publisher. LAMPS OF DIFFERENT CANDLE-POWERS. If lamps of different candle-power (that is, having different currents) are mixed and are on the same circuit, they must either all be reduced to their equivalent in terms of the same lamp, or else if there are only two or three kinds, the leads may be determined in circular mils (not in gauge numbers) for each batch of like lamps separately, and the sum of all the circular mils taken, from which sum the gauge numbers are .then found from a table or from the double scale on the chart. POWER LEADS. For the distribution of power, start with the line (near the bottom of the chart) representing a one-ampere lamp, then the numbers representing lamps in the upper left hand field will represent amperes of current. The current in amperes cor- responding to the horse-power must, of course, be determined first from the horse-power and the volts (see table of horse-power equivalents, pages 36 and 37). THREE-WIRE SYSTEM. If the wiring is to be done for the three- wire system in which three wires of like size are used in place of two, the cross-section of each will be one-fourth as great as that for the ordinary system. , Instead of finding the cross-section from the charts and dividing it by four, and then finding the gauge number from a table, it is much simpler to proceed as before, but taking either one-fourth the number of lamps or one-fourth of the distance, or four times the loss. By doing it in this way the size of wire is obtained directly without the use of any table, while the only calculation necessary is merely a mental one. OTHER USES OF THE CHARTS. The charts may be used back- ward, so to speak, by starting with a given size of wire and work- ing backward to find what the loss will be for a given number of lamps at a given distance. In the same way, the allowable number of lamps or the distance may be determined if the other quantities are given. In general, any one of the quantities may be found if all the others are given ; the general rule in that case is to start from the beginning and end of the chart simultaneously, and con- tinue as usual until the two lines which one is following intersect in the common field which contains the diagonals representing the quantity looked for; that diagonal which passes through EXPLANATION OF THE CHARTS. 7 or nearest to this intersection represents the number sought for. For instance, how many .775-ampere lamps will a No. 11 wire carry, to a distance of 50 feet, with a loss of 1 volt? See the first chart, broken line. Starting with the line represent- ing a .775-ampere lamp, follow it to the 1 volt loss line ; thence up into the field representing lamps ; then begin with the intersection of the dotted line representing a No. 11 wire and the 50 feet line, and follow backward (see broken line) to the lamp field ; where it crosses the other line, find what diagonal passes through this point ; this diagonal, namely 10 lamps, is the required number of lamps. AUXILIARY TABLES. At the end of the book there are some tables which will frequently be found useful in connection with wiring determinations. MANY LAMPS AT A GREAT DISTANCE. If the leads are to be determined for many lamps at a great distance, a small error in the determination signifies a considerable difference in cost of the wire ; the computation must therefore be made more accurately. To do this would require a chart of very great size. It is there- fore preferable to calculate such exceptional determinations by means of one of the following rules : If the total current is given : multiply the total current by the dis- tance in feet and by 21.21, and divide by the loss in volts ; the result will be the required cross-section of the leads in circular mils. If the current per lamp is given : multiply the current per lamp by 21.21 ; this gives the " constant "; multiply the number of lamps by the distance in feet and by this " constant" and divide by the loss in volts; the result will be the required cross section in circular mils. The gauge numbers corresponding to these cross sections will be found in the tables at the end of the book, page 23. For very large cross sections a 'table is given showing what sizes of wires bunched together will make this cross-section. (See page 28). BASIS OF THE CHARTS. The basis of these charts (as also that of the tables and formulae in this book) is a resistance of 10.61 legal ohms per mil foot of copper wire. In terms of the Matthies- sen standard suggested by the Committee of the American Insti- tute of Electrical Engineers (namely, 9.612 legal ohms per mil foot at C.), this is equivalent to the resistance at, about 75< to 80 F. As pure copper of the present time sometimes has even less resistance than that referred to in this standard, it is thought 8 WIRING COMPUTER. that the value chosen for these charts and tables represents a fair t .value for the resistance of good copper at the average normal tem- perature. As the accidental differences in the 'actual diameters of the wires introduce errors far greater than a slight difference in the assumed standard conductivity, it would not be reasonable to attach much importance here to great precision in the assumption of the standard. All that is necessary here is to select the fairest possible value for actual practice, to state what this value is, and to have it the same throughout this whole set of charts, tables and formulae. 12 Li in p.9 1 1 1 I 18 20 22 ft i 20 30 i 6 4 ) 50 i (1 : n \ \ \ \ \ \ \ \ | \ i \ 1 \ \ \ \ \ \ \ \ \ S x \ \ \ \ \ 11 v \ \ \ 1 \ 5 \ \ 1 \ \ v . \ \ \ 5 \ \ \ \ \ \ \ \ \ \ 1 & \ \ \ \ \ k V \ \ \ ^ Q 10 \ \ s, \ \ ^ \ s \ \ N \ ^. \ \ \ \ X , V \ N \ \ 1 \ \ \ \^ ^ \ \ \ \ \ \ \ \ 1 9 \ \ k \ ] \ \ ' \ \ \ \ \ \ \ \ > \ \ \ ^ \ V \ \ \ \ -x s, ! \ \ JL \ \ \ s \ \ \ 8^ Vy \ \ N \ \ \ ^ \ X x. Vy \ \ s, \ N. \ \ \ \ s ^ x^ \ \ s, \ \ \ \ ~ , \ x \ ' , X \ \ \ \ \ \ \ \ \ \ \ \ ^ - \ 7 > x \ - \ - \ \ \ \ ^ \ I X X V \ V Vk \ \ \ ; \ , ^ ; N \ \ N, \ \ \ \ \ \ - \ \ ' X \ s X \ So s. \ x ^ \ \ \ i \ \ \ 1 JL 6s s K^ x^ s S^ x > v \ \ ^ \ \\ \ \ V \ X .. x x x. s s^ \ \ \ \ \ \ i \ ^ X t ' > v -. X >y \ \ \ \ \ \ \ f \ \\ ^_ \ ., x, X \ v \^ x - \ s \ \ \ ^ \ \ \ 1 \, \\ ~ 5, "X s. X X. x \ \ \ \ \ \\l \ \ h \\ ** ^ \ x X N. x \ \ S \ \ ' \ \ \ \ s^ X x^ X X^ X x X, \ \ \ - \ A \\ \ \ \ \ \ ~ s '^ ^ v X K. N x^ " \ \ . s^ , \ \ \ S " N |T \ \ \ \ LI: 4^ s^ x . X s^ \ \ , A *- r- jr A _\ - \- ' ^. ^ ^ \ " x X s x, \ s^ s \ \ V \ \ \ "1 jj ^ .. x ^ >s x^ X X^ s K x \ '- s^ 5 \ \ , \ \ P. - . -^ --. Xv, X ., X X s - x^ s \k \ " \ \ \ \ \\ ' B 3, " "* ^, ^s, " ^ - Xs, x s^ > X, \ \ - ^ s.\ \ \ \ \ \\ ^ 1 . "-.^ - ~^ ^ x X, x v^ x^ s x s ^ v Sk^ s \ 5 V \ f \ *~-~. ^^ V. - ^- ^ X s " x x s \ '\ \ \ \ 3 , i \ : - * . ^ ^^ ""* X, X N x S \ \ s s \ Mt fr . - ^. ~-^^ -^ ^ "^-^ x |^ ^ X^ X \ \ \ \ v ^ N v V\ . 1 ~ ~- -- .., -> ^^ ^ L^ s x X ^ s s \ \ V \\ \\\ " ^ - - -_ ^_^ ^ >^, ^ X. X. \ s v s s s l s \ \ \ S^- 5 " -- "^-v. N. *^. "X s, s V\ k\ \ I- 7 = =r ^z ~ . =- .- \ - ~ "-^ --^- -^-^ "-] * *. - - - - -a- = =a ==- ^=r " . ~ ^- =: \ -^i. =i ->^ - -=i s -^Z z=^ ^-C ^^ ~- . r^. =^ ^C -^^ -^ ^z t" v 5^^ : 1 ^ - . ^ x, -^ *^ . i ^1 i \ 1 ~-~- ^-f - ' f - -^ ^~ ^*- r^ I - ^ .-^ ^** ~ ^ . " ^ H% . - ^ ^ s ' / '4 / // 'i ^-i .'- s / ,. / n .2- *~* < = r- :T , ^ -:' <.*- ;;; ^^ ^ -^ s -^ ? 7* / Z ,/ 1 ^ , ' ^f ^ g S / -' / / /I ] .... ^~- -- ^ ,, / ' J / i / _.._. - " ^ ^ ,- ? / / / 2 - Lu .3- ** s /' /> ^ / i : \f . ^ ~ J^ -' ^ / / ' / ~LL * 3 ^* -*" - ' ^ ^ s / / / / I ^ -- - s / /^ / _/ * a A / " / i " t tD /> / / / / / o s ? / / / / / / / , t s" ' *- S - s 1 ' : "s ,. s . , , / i I ^ ^ ' ,, ^ / 1 / i I .6' ,.- ^ - , / '. 1 /f / / ' 1 .7 Loss in volts. .9 1. 1.2 1.5 Copyright, 1891, 98 7 B. & S. Gauge Numbers. FEW LAMPS AT SHORT DISTANCES. Rule for using the chart: Follow the general direction of the broken line and the arrows, from one set of diagonals to the next. EXAMPLE: What size wire is required for 10 lamps of .775 amperes each, at 50 feet, for a loss of 1 volt? SOLUTION : Starting with the current for 1 lamp, .775 amperes (see scale below center), follow it (see broken line and arrows) to the left, until it intersects the diagonal represent- ing 1 volt loss ; thence up to the diagonal representing 10 lamps ; thence to the right to the diagonal representing 50 feet, and from here down to the scale of the circular mils or gauge numbers, on which the reading is found to be about 8,200 circular mils, or a No. 11 B. & S. wire. For a more detailed explanation, abbreviated, raetbods-and gerv?ral5iiots, see text. ARL IIERING. 12 Lamps 14 18 20 22 24 26 30 35 40 50 60 70 Lamps \ S s \ \ \ \ | \ " t i \ \ \ \ \ ^ \ \ \ \ 3 \ \ \ \ i \ 11 \ \ \ V \ \ \ \ \ \ \ ^ \ \ \ \ \ n, \ \ \ \ ' \ \ \ - R 10 . \ \ . v \ ,1 5 \ \ \ \ ^y \ \ \ \ \ \ - \ \ \ - \ \ ' \ \ \ . \ \ \ 1 9 % x \ \ \ \ \ \ ' \ \ - \ J \ \ ,' \ \ V \ \ \ \ \ A \ u * i i 8> S^ S. i * - \ ^ i i_ i T s X - N N s s \ \ \ \ \ \ 1 -1 H- X N, \ N - \ \ \ , , 7^ X " \ x, \ | \ k \ 1 B \ 1 s s s \ s s \ N \ \ \ \ \ 1 \ \\ U fx s ^ s. \ \ . k \ \ \ \ 1 i . X X, ' \ Sj X . \ ' \ \ \ \ - 6 N ^ X \ \ S. \ S, ^ \ \ ' \ 1 \\ X b x N X - \ N. \ N s j \ \ ; J \ \l\ X X s V ' N \ s \ \ \ \ ^ \ \ 1 - ix x, s X s "V s X \ \ ' ( \ \ 1 , \\\ - 5> > X, \ x, ^ ^ S ' \ \ \ \ N \ \ \ X^ X. S X V. \ \ \ s ^ v \ \ { I \ ^ *X - X - N X X S ' \ y \ \ \ Y A- w- 4 ^ X- "X, - [x \^ ^ ^ X "\ X s ^" y ^~ y _\ MtV te~- ^ X '"s v *N x . > \ x, \ \ \ \i 3j B ^ a - 'x s^ X s X x - s 3 K \ N^ - V A \ pr n ro --, s *- ^ ^ ^x ^ -. x x x *\ \ 5 \ \ \ \^ \ \ M\ & 3^ ^v ^ "V ^ x, s * . !s jj \ X^ -, ^ ^ s ^ a PR \ 1 ^ . -. v ^ , x . x ^ > \ -. x X s^ x ^ 3 \ \N \ . ~- ^, *^, L^ > - s^ N^ 1 5 s \ X, x \ , s \ \v I \ u -- -^ __^ "" -~* *^, -- ~^ ^~ ^ - . ^> ^ -. -x v x X s \^ \ ' \v \\ 2-, ^- ~ L ^^ I |^, K -- ^. s "X x. \ V \ EL . - __ - ^- v. 5 5 -^ " - 5 ^ x s x t\ \ \ NSK k \ \ *-^, - , -~. - - ._^ . "^**. ^^, 5= ^. ^ : ,^ \ x x, ^ x. S s - s \i\ SK n - ^ - , ^~ '-- & *^-* **^J *x ^ v ^ ^ 3S \~ "u 1. -^i = ___ ^ , 1 -i=< -^^: - . ^ . =-. -=3 ._ -~_. "" ' "-^, i - =*^ >> =c ^ i^ -^ ^ !^s. ^x*. ^ ^ l\\ f mm MM f Ml mm 1 MMl M. { MM MM + **a Ml i , MM = t r-. MB *- = ! ^=: -' , t ^ (MM -- ' - ^ _^> MM . _- ^~~. MM . ^ SM. "^ MM ^*~ *^c= MM - - ^^ f ^~- - , mm J ^1 I 1 ^r^ ^ li ^*- ^ ~~ ^ ^ - ~ =- = ^f -^ ~ S r* /j .4. -=" e =rr -= '_ ~ ^ -/* S* ^ '7 / ' i / /]/ " - - ^ ^ ^ ' / ' / /I 1 * ^* ^^ " s> ., / / / 1 ^ , / ^ , / /' ' / / ' , <- .6 ' / / / ,'- { } ^* s ^ | - 4 / / / -S ^, s / / fi / o ^ ^" / S* / / ' -6 - c s* / 2 t~- -- - -7 ~r *~" 'w ^ ^ ^f / / / f I /i/ <- ^ '" ^ ^ s / / / t-'- n ^ ^ ' , / / i 1 1- S / ' / 1 i / ,, / , / - 1 / / <- S\ / / f , i / / 1 1.2 s ^ / / <. / / / / 1 ! 1 1.4 1.6 1.8 Loss in volts. 2. 2.4 . 8. 10. Copyright, 1891, 50 100 150 200 250 300 Feet 400 500 8 ! 3 2 i o B. & S. Gauge Numbers. 00 <=" o~ g fe FEW LAMPS AT DISTANCES. Rule for using the chart : Follow the general direction of the broken line and the arrows, from one set of diagonals to the next. EXAMPLE: What size wire is required for 10 lamps of .775 amperes each, at 500 feet, for a loss of 2 volts? SOLUTION : Starting with the current for 1 lamp, .775 amperes (see scale below center), follow it (see broken line and arrows) to the left, until it intersects the diagonal represent- ing 2 volts loss ; thence up to the diagonal representing 10 lamps ; thence to the right to the diagonal representing 500 feet, and from here down to the scale of the circular mils or gauge numbers, on which the reading is found to be about 42,000 circular mils, or a No. 4 B. & S. wire. For a more detailed explanation, abbreviated, aeib 2 _21.21 CD E in which D is the distance in feet from the dynamo to the lamps or motor, and E is the loss in volts. For arc light circuits this formula is in its simplest form, and for motor circuits also, after having first determined the current (7, which is equal to 746 times the horse-power divided by the volt- age of the motor, or which may be found from the tables of horse- power equivalents in the back of this book, see pages 36 and 37. 1 This constant is in accordance with the new Matthiessen standard suggested by the Com- mittee of the American Institute of Electrical Engineers. (18) WIRING FORMULA. 19 For incandescent lighting this formula may be still further simplified by substituting the number of lamps n for the current O, in which case it is necessary to introduce the constant c, which is the current required by one lamp. This is usually multiplied once for all by 21.21, giving what is generally termed the "con- stant " for calculating the leads for that lamp. The formula then becomes in which the quantity in parentheses is the " constant " calculated once for all. This constant is then divided by the actual loss in volts, E (not in per cent.), which gives a new constant, but for that loss only. The calculation is therefore as follows : Multiply the number of lamps by the distance in feet and by the constant (which constant has first been divided by the loss in volts). The answer is the cross- section in circular mils. From a table (see page 23) find what gauge number this corresponds to, or from a table of squares or square roots find the diameter in mils of which this is the square. If lamps of different candle-power (and therefore of different currents) are used together, it is best to reduce them all to thd equivalent in one size, or else find the total current in amperes, and use the original formulae in which the current is used instead of the number of lamps. The loss is often given in per cent, instead of in volts. To find what this is in volts, it is necessary merely to multiply the voltage of the lamp, V, by the per cent, (in whole numbers, thus, 2 per cent.) and divide by 100. Or to bring this all into the formula gives in which V is the voltage of the lamps, and % is the loss in per cent, (in units, thus, 2). Instead of giving the cross-section in circular mils, namely, d\ the formula might be made to give it in square mils, but the very good practice of using circular mils instead of square mils has become so universal and is so much simpler, that the other is no longer to be recommended. To change the above formulae so as to give the answer in square mils instead of circular mils, multi- ply the numerical constant by .7854, and change d* to a. From the above explanation regarding the " constant " anyone 20 WIRING COMPUTER. will be able to calculate the constant for any make of lamp. It is always best to calculate this, unless one is very sure what the constant given by the makers means. To determine the constant it is necessary to have the current required for one lamp ; when- ever possible, it is best to measure this one's self for a batch of 10 or 100 lamps, as the figures given by the makers are sometimes considerably below their true values. TABLES. PAGE Tables of Wire Gauges 23 Table of Compounded Wires of Large Cross Section .... 28 Table of the Weight and Resistance of Copper Wire 30 Table of Temperature Corrections for Copper Wire 32 Weight of Insulated Wire for Wiring 33 Table of Heating Limits or Maximum Safe Carrying Capacity of Insulated Wires ... 34 Table of Horse Power Equivalents . , . 35 Wiring Tables 1 . 38 (21) TABLES OF WIRE GAUGES. 23 TABLES OF WIRE GAUGES. Tables giving the diameters and cross-sections of different wire- gauge numbers are usually given separately, or, if together, they usually give approximate equivalents only. As the latter is often insufficient, the accompanying table has been arranged to give in the order of their size all the values for each of the principal Ameri- can and European gauges. All the approximate equivalents may, therefore, be readily found by mere inspection, while the degree of approximation may be seen directly from their cross-sections or diameters. It therefore forms a complete and combined set of all the gauges used in practice. The tables usually published often give only approximate diam- eters and cross-sections, and some of them contain a number of errors. The accompanying table has, therefore, been calculated from the original correct data. It may not be generally known that the tables of B. & S. gauges, as usually published, contain a number of errors which were apparently copied from an incorrect original, and have been acknowledged to be errors by the origi- nators. The corrected values have been used in this table. In connection with the B. & S. gauge, it may be added here that it follows a regular law, each cross-section being a -certain per cent, smaller than the one before. It may not be generally known that with every three sizes the cross-section is doubled approxi- mately. Thus, No. 4, for instance, is very nearly twice as large in cross-section as No. 7 and half as large as No. 1. The error is only one-quarter of 1 per cent. This rule applies to the whole range of the gauge. The accompanying table may be used also for converting diam- eters into areas, millimetres into mils, diameters of the one into areas of the other units, etc., and vice versa. 24 WIRING COMPUTER. TABLES OF WIRE GAUGES. American and European. WITH CROSS-SECTIONS AND DIAMETERS Arranged for Comparison and Reduction. GAUGES AND SCALES. CROSS-SECTION. DIAMETER. 8 1 fi 1 " i. * MILLIMETER SCALE. (Diam. in Millimeters.) DECIMAL SCALE. (Diam. in Mils.) EDISON GAUGE. BIRMINGHAM, or Stubs (Holzapffel) or Old English Standard Gauge. B.W.G. NEW BRITISH, or Standard Gauge (March 1st, 1884). American or B. & S. GAUGE. CIRCULAR MILS. (=- d) (1 Circular Mil .7854 Square Mils.) SQUARE MILS. (1 Sq. Inch = 1,000,000. Sq. Mils.) SQUARE MILLIMETERS. (1 Sq. m. m. 1550.1 Sq. Mils). MILLIMETERS. (1 m. m. =- 39.3708 Mils.) MILS. (<=d). (1 Inch 1,000. Mils.) II. in. IV. v. VI. VII. VIII. IX. 506.69 285.01 197.93 182.41 172.28 "miT 152.01 141.88 131.74 126.68 XI. XII. 1000 750 625 1 OOO OOO. 562 5OO. 39O625. 36OOOO. 34O OO6. 785398. 441 786. 3O6 796. 282 743. 267 O4O. 25.400 19.050 15.875 15.240 14.810 1OOO.O 75O.OO 625.00 600.00 583.10 360 340 320 300 280 260 32OOO5. 3OOOO8. 28OO1O. 26OOO8. 25OOOO. 251 332. 235626. 21992O. 2O421O. 196 35O. 14.365 13.912 13.440 12.952 12.700 "12^43- 11.914 11.785 11.684 11.531 565.69 547.73 529.16 509.91 500.00 JL 5OO 7/0 .... 240 220 24OOO2. 22OOO8. 215296. 211 6OO. 206116. 188497. 172794. 169 O93. 166190. 161883. 121.61 111.48 109.09 107.22 104.44 489.90 469.05 464.00 46O.OO 454.OO 6/0 OOOO oooo 45O 2OO 2O2 5OO. 2COOO6. 191 4O6. 190000. 186624. 159O43. 157084. 150330. 149226. 146574. 102.61 101.34 96.98 96.27 94.56 11.430 11.359 11.113 11.071 10.972 450.00 447.22 437. 5O 435.89 432. OO Ks 19O 5/0 425 18O ooo 180625. 180005. 170008. 167805. 16OOOO. 155006. 150001. 1444OO. 14O625. 14OOO3. "1398937 138384. 133079. 13OOO4. 125555. 141863. 141376. 133524. 131 79O. 125664. 91.61 91.21 86.14 85.03 81.07 10.795 10.776 10.473 10.405 10.160 425.00 424.27 412.32 4O9.64 4OO.OO 17O 000 400 16O OOOO 1O 15O 121 74O. 117811. 113411. 110450. 109958. 78.54 76.00 73.17 71.25 70.94 10.000 9.837 9.652 9.525 9.504 393.71 387.30 380.00 375. OO 374.17 oo % 375 14O : fi OOO ' 00 ' 1O9858. 108687. 104518. 1O2 1O5. 98 588. 70.88 70.12 67.43 65.87 63.62 9.500 9.448 9.266 9.158 9.000 374.02 372.00 364.80 360.56 354.34 350.00 348.00 346.42 343.75 34O.OO ISO 9. 35O OO 122 500. 121 104. 120007. 118 164. 1156OO. 96211. 95115. 94253. 92810. 9O792. 62.07 61.37 60.81 59.87 58.57 8.890 8.839 8.799 8.731 8.636 12O & 340 ^ f> no 111992. 11OOO5. 1O5625. 1O5534. 1O4976. 100001. 992O4. 97656. 95OO5. 9O OOO. 87968. 86398. 82958. 82887. 82 448. 78541. 77914. 76 699. 74617. 70686. 56.75 55.74 53.52 53.47 53.19 8.500 8.424 8.255 8.2-51 8.229 334.65 331.67 325.00 324.86 324.00 325 o R 1OO 50.67 50.27 49.48 48.14 45.60 8.032 8.000 7.937 7.829 7.620 316.23 314.97 312.50 308.23 300.00 *A* 95 3OO 9O 1 1 'l.h 85 87191. 85001. 83 694. 80656. 80 004. 68 479. 66 76O. 65732. 63347. 62835. 44.18 43.07 42.41 40.87 40.54 7.500 7.405 7.348 7.213 7.184 295.28 291.55 289. 3O 284.OO 282.85 1 2 80 2 79 1O2. 76 176. 75953. 75625. 75 OO5. 62 ISO. 59828. 59653. 5939O. 68 9O8. 40.80 38.59 38.48 38.32 38.00 7.144 7.010 7.000 6.985 1 6.956 281.25 276.OO 275. 6O 275.OO 273.87 7 275 75 Copyright, 1891, by CARL BERING. TABLES OF WIRE GAUGES. 25 GAUGES AND SCALES. CROSS-SECTION. DIAMETER. Millimeters. 1 ! M British. 02 *5 fg ! a * Square Millimeters. Millimeters. | I. II. III. IV. V. VI. VII. VIII. IX. ~549807 52 685. 52 128. 51 436. 51 O55. X. -35.47 33.99 33.63 33.18 32.94 XI. XII. 7O 70003. 67O81. 66373. 65 49O. 65OO5. 63 5O4. 62 5OO. 6OOO1. 56.644. 558O2. 6.720 6.578 6.544 6.500 6.476 264.58 259. OO 257.63 255.91 254.96 3 2 6.5 65. y* 25O 3 49876. 49 O87. 47 124. 44488. 43827. 32.18 31.67 30.40 28.70 28.27 6.401 6.350 6.222 6.045 6.000 "5.957" 5.952 5.893 5.827 5.715 252. OO 250.00 244.95 238.00 236.23 6O 4 6. it 55 55 OO4. 54932. 53824. 52 634. 50625. 43 2OO. 43 143. 42273. 41 339. 39761. 27.87 27.83 27.27 26.67 25.65 234.53 234.38 232. OO 229.42 225. OO 4 3 225 5O 5 5OOO1. 48 4OO. 47852. 46889. 45 OO3. 39271. 38O13. 3758O. 36827. 35346. 25.34 24.52 24.25 23.76 22.80 "22.7T 21.15 20.91 20.88 20.27 5.680 5.588 5.556 5.500 5.388 223.61 22O.OO 218.75 216.54 212.14 & 5.6 45 5 44 944. 41 743. 41 26O. 41 2O9. 4O OOO. 38752. 36864. 36 1OO. 35713. 35 156. 35299. 32 784. 32 4O5. 32365. 31416. 5.385 5.189 5.159 5.156 5.080 5:000 4.877 4.826 4.800 4.762 212.OO 204.31 2O3.13 2O3.OO 2OO.OO 4 M 6 2OO 40 6 SO 435. 28953. 28 350. 28055. 2761O. 19.63 18.68 18.32 18.10 17.81 196.85 192.OO 19O.OO 188.98 187.50 i 4.8 19O 35 5 35OO2. 33 1O2. 32 799. 32 400. 31389. 27491. 25999. 2576O. 25447. 24647. 24328. 23569. 23563. 232O3. 22698. 17.44 16.77 16.62 16.42 15.90 4.752 4.621 4.600 4.572 4.500 187.O9 181.94 181.11 180.00 177.17 4.6 18O 7 4.5 J4 4- 7 SO 976. 3OOO9. 30002. 29541. 289OO. 15.69 15.21 15.20 14.97 14.64 ~13^5" 13.79 13.30 12.97 12.67 "12.57 12.37 11.40 11.34 11.10 4.470 4.400 4.400 4.366 4.318 176. OO 173.23 173.21 171.88 17O.OO 165.36 165.OO 162. 02 16O.OO 158.12 157.48 156.25 15O.OO 149.61 148.00 3O ff 17O 4tt 8 27343. 27225. 2625O. 256OO. 25OO2. 21 475. 21 382. 2O618. 20106. 19636. 4.200 4.191 4.115 4.064 4.016 6 16O 8 25 * 4 248O1. 24414. 22 5OO. 22383. 21 9O4. 19479. 19170. 17671. 17579. 172O3. 4.000 3.969 3.810 3.800 3.759 38 150 x 9 9 7 2O82O. 2O 736. 2OO89. 2OOO2. 19776. 16351. 16286. 15778. 15710. 15532. 10.55 10.51 10.18 10.14 10.02 "9.931" 9.621 9.098 9.079 8.563 8.365 8.302 8.042 7.917 7.601 3.665 3.658 3.600 3.592 3.572 144.29 '1 44.OO 141.74 141.43 140.63 3 6 A 3 5 14O 196OO. 18988. 17956. 17919. 169OO. 15394. 14913. 141O3. 14073. 13273. 3.556 3.500 3.403 3.400 3.302 14O.OO 137.8O 134.OO 133.86 130.00 10 3 4 130 1O 8 1651O. 16384. 15873. 15625. 15OO1. 12967. 12868. 12466. 1227O. 11782. 3.264 3.251 3.200 3.175 3.111 128.49 128. OO 125.99 125.00 122.48 3 2 K 15 3. 12O 11 144OO. 13951. 13456. 13092. 12 152. 11 31O. 10954. 10568. 10283. 9545. 7.296 7.069 6.818 6.634 6.158 "6.131 6.081 6.061 6.020 5.480 3.048 3.000 2.946 2.906 2.800 12O.OO 118.11 116.OO 114.42 11O.24 9 . . . a a no 12 12 1OO. 12OO1. 11 963. 11 881. 1O816. 9503. 9426. 9395. 9331. 8495. 2.794 2.783 2.778 2.769 2.642 11O.OO 1O9.55 1O9.38 1O9.OO 1O4.OO A 12 12 Copyright, 1891, by CARL HERING. 26 WIRING COMPUTER. GAUGES AND SCALES. CROSS-SECTION. DIAMETER. j 1 Decimal. ! 6 t M British. OJ 3 M ii js & Square Millimeters. Millimeters. 1 I. ii. in. IV. V. VI. VII. VIII. IX. X. XI. XII. 2.6 10 1O478. 1O384. 1OOOO. 9688. 9025. 8 23O. 8 155. 7854. 7609. 7088. 5.309 5.261 5.067 4.909 4.573 2.600 2.588 2.540 2.500 2.413 1O2.36 1O1.9O 1OO.OO 98.43 95.OO 100 2 5 95 13 A ! 4 8928. 8789. 8464. 8234. 8100. 7O12. 6903. 6648. 6467. 6362. 4.524 4.453 4.289 4.172 4.104 2.400 2.381 2.337 2.305 2.286 94.49 93.75 92.OO 9O.74 9O.OO "89.45" 86.62 85. OO 83. OO 8O.81 8O.OO 78.74 78.13 75.OO 74.81 13 . .^. . 9O 2 2 8 8OO1. 7502. 7226. 6889. 6530. 6284. 5892. 5675. 5411. 5129. 4.054 3.801 3.664 3.491 3.309 2.272 2.200 2.160 2.108 2.053 85 14 12 2 O 8O 14 64OO. 6200. 6104. 5625. 5596. 5027. 4870. 4793. 4418. 4395. 4072. 4067. 3944. 3928. 3848. 3.243 3.142 3.093 2.850 2.835 2.032 2.000 1.985 1.905 1.900 * 1.9* 75 15 15 13 5184. 6179. 6022. 6001. 49OO. 2.627 2.624 2.545 2.534 2.483 1.82? 1.828 1.800 1.796 1.778 "LTOr 1.651 1.628 1.626 1.600 72. OO 71.96 7O.87 7O.72 7O.OO 1 8 5 7O .... 7 65 16 4480. 4225. 4107. 4096. 3968. 3518. 3318. 3225. 3217. 3 116. 2.271 2.141 2.081 2.078 2.011 66.93 65. OO 64.O8 64.OO 62.99 14 16 1.6 Me 6O 39O6. 3600. 3488. 3364. 3257. ~~3T36T~ 3O38. 3O25. 3OO1. 262O. 2583. 25OO. 24O1. 23O4. 2232. 2 197. 2O48. 2O25. 1875. 1 764. 1 624. 1 6OO. 1 55O. 1296. 1288. 3O68. 2827. 2739. 2642. 2 558. 1.979 1.824 1.767 1.705 1.650 1.589 1.539 1.533 1.521 1.327 1.588 1.524 1.500 1.473 1.450 1.422 1.400 1.397 1.391 1.300 62. 5O 6O.OO 59. 06 58.OO 57.07 1 5 17 15 17 2463. 2384. 2376. 2357. 2O57. 56. OO 55.12 55.OO 54.78 51.18 1 4 55 3 1,3 5O 16 2O29. 1 964. 1 886. 181O. 1 753. 1.309 1.267 1.217 1.167 1.131 1.291 1.270 1.245 1.219 1.200 5O.82 5O.OO 49.OO 48. OO 47.25 18 18 1 2 i 17 1 726. 1 6O9. 1 69O. 1 473. 1 385. 1.113 1.038 1.026 .9509 .8938 ^8230- .8107 .7854 .6567 .6527 1.191 1.150 1.143 1.100 1.067 46.88 45.26 45.OO 43.31 42. OO 45 1 1 19 4O 19 18 1276. 1257. 1217. 1 O18. 1 O12. 1.024 1.016 1.000 .9144 .9116 4O.3O 4O.OO 39.37 36.OO 35.89 35.43 35.OO 32. OO 31.96 31. 5O 19 .9 85 20 21 1 256. 1225. 1 O2 4. 1O22. 992.0 985.9 962.1 8O4.2 802.3 779.3 767.O 7O6.9 636.3 615.8 696.5 .6362 .6207 .5188 .5176 .5027 .9000 .8890 .8128 .8118 .8000 21 20 ,8 * 976.6 9OO.O 81O.1 784.O 759.5 .4948 .4560 .4105 .3972 .3848 -^425~ .3255 .3167 .2919 .2827 .7937 .7620 .7229 .7112 .7000 31.25 3O.OO 28.46 28. OO 27.56 26.OO 25.35 25. OO 24.OO 23.62 ... SO 21 28 22 22 7 26 22 676.O 642.5 625.O 576.O 658. 63O.9 6O4.6 49O.9 452.4 438.3 .6604 .6438 .6350 .6096 .6000 25 24 23 23 fl 22 . . . . 24 24 23 5O9.5 48 4. 4O4.1 4OO.O 387.5 4OO.2 380.1 317.3 314.2 3O4.4 .2581 .245? .2047 .2027 .1963 .5733 .5588 1 .5106 .5080 i .5000 22.57 22.00 20.1O 2O.OO 19.69 24 20 25 25 5 Copyright, 1891, by CARL HEBING. TABLES OF WIRE GAUGES. 27 GAUGES AND SCALES. CROSS-SECTION. DIAMETER. a ~TT~ Millimeters. 1 Edison. e British. || 9 M |j \i F 1 u X. J i n. III. IV. v. VI. VII. VIII. 361 .0 324.O 32O.4 313.9 289. IX. 283.5 254.5 251.7 246.5 227. 211.2 2O1.1 199.6 194.8 191.8 XI. 7482T .4572 .4547 .4500 .4318 XII. 19. OO 18. OO 17. 9O 17.72 17. OO 18 26 26 .1832 .1642 .1624 .1590 .1464 7i363~ .1297 .1288 .1257 .1237 25 45 17 16 27 27 269.O 256.O 254.1 248.O 244.1 .4166 .4064 .4049 .4000 .3969 16. 4O 16.OO 15.94 15.75 15.63 26 15 28 225. 219.0 201.5 196.0 189.9 176.7 172. 158.3 153.9 149.1 .1140 .1110 .1021 .09931 .09621 .3810 .3759 .3606 .3556 .3500 T345T .3302 .3211 .3150 .3048 15.OO 14.80 14.20 14.00 13.78 27 35 14 28 13 29 29 185.0 169.0 159.8 153.8 144.O 145.3 132.7 125.5 120.8 113.1 .09372 .08563 .08097 .07792 .07296 .07069 .06818 .06421 .061 58 .06087 13.60 13. OO 12.64 12.4O 12.OO 28 SO 12 30 a 31 139.5 134.6 126.7 121.5 121.O 109.5 105.7 99.53 95.45 95. 03 91.61 82. 3O 78.94 78.54 7O.12 .3000 .2946 .2859 .2800 .2794 11.81 11. 6O 11.26 11.O2 11. OO 28 29 11 .... .26 32 116.6 1O4.8 1OO.5 1OO.O 89.28 .05910 .053 09 .05092 .05067 .04524 .2743 .2600 .2546 .2540 .2400 1O.8O 1O.24 1O.O3 10.00 9.449 30 10 31 33 914 9 . . . . 32 34 84.64 81. OO 79. 7O 75.02 70.56 66.48 63.62 62. 6O 58. 9O 55.42 .04289 .04104 .04039 .03801 .03575 .2337 .2286 .2268 .2200 .2134 -^032" .2019 .2000 .1930 .1800 -J798" .1778 .1727 .1601 .1600 TI524 .1426 .1400 .1321 .1270 9.2OO 9.000 8.928 8.662 8.4OO 7i950 7.874 7.6OO 7.O87 31 9, 9. 35 8 33 32 64.OO 63. 2O 62.00 57.76 50.22 5O.27 49.64 48.70 45.36 39.44 .03243 .03203 .03142 .02926 .02545 ^02539" .02483 .02343 .02014 .02011 no 36 IB 7 . . . . 34 33 50.13 49.00 . 46.24 39.75 39.68 39.37 38.48 36.32 31.22 31.15 7.O8O 7.OOO 6.8OO 6. 305 6.299 37 34 16 6 38 36 36.00 31.53 3O.38 27.O4 25.OO 23.04" 22.32 19.83 19.36 18.75 28.27 24.76 23.84 21.24 19.64 .01824 .01597 .01539 .013 70 .01267 Toner .01131 .01005 .0098 09 .0095 03 T008107 .007967 .007854 .006561 .006362 6.OOO 5.615 5.512 5.2OO 5.OOO 14 39 5 35 36 .18 37 17.53 15.57 15.21 14.73 .1200 .1131 .1117 .1100 4.725 4.453 4.4OO 4.331 41 1 1 4 36 42 38 16.00 15.72 15. 5O 12.96 12.56 12.57 12.35 12.17 10.18 9.859 .1016 .1007 .1000 .0914 .0900 T689T .0813 .0800 .0799 .0762 4.OOO 3.965 3.937 3.6OO 3.543 .10 43 OP 44 39 12.47 lp.24 9*920 9.888 9.OOO 9.793 8.042 7.793 7.766 7.O69 .006318 .005191 .0050 27 .005010 .004560 .003972 .003848 .002918 .0028 27 .0020 27 "^01963 .0012 97 .000730 .0005.07 3.531 3.2OO 3.15O 3.145 3.OOO 2i756 2.400 2.362 2.000 OR 40 3 07 45 7.84O 7.595 5.760 5.580 4.000 6.158 5.965 4.524 4.383 3.142 .0711 .0700 .0610 .0600 .0508 To5oor .0406 .0305 .0254 46 00 2 47 Oft 48 49 5O 3.875 2.56O 1.44O l.OOO 3.044 2. Oil 1.131 .7854 1.969 1.6OO 1.2OO l.OOO 1 Copyright, 1891, by CARL HERING. 28 WIRING COMPUTER. COMPOUNDED WIRES OF LARGE CROSS-SECTION. In wiring, it is sometimes necessary to use wires larger than No. 00, B. & S. - gauge. It then becomes necessary to compound the wire, not only because No. 00 is the largest size which it is prac- ticable to lay (unless the wire is stranded), but chiefly because the size wanted does not generally happen to correspond with those of the gauge numbers ; and as the length of the wires is often great, a small excess over the required cross-section may signify a con- siderable increase in the cost. In such cases it is, therefore, often desirable to obtain the closest possible approximation to the re- quired cross-section by the best combination of the sizes in the market. The table gives every possible combination of the four largest wires which it is practicable to use, namely, Nos. 2, 1, and 00 B. & S. gauge. The combinations are classified in the order of their combined sections. Having given the desired cross-section of a compounded wire, for instance, 400,000 circular mils, look for this size in the second column, then all the possible combinations which approximate this most closely will be found near to it in the adjoin- ing first column. In this case it will be seen from the 'table that three No. wires and one No. 1 will give it very closely ; and there is no other combination which will give it more closely. Furthermore, the values often do not differ very much from each other, thus allowing some choice, which is often desirable. For instance, in this case it will be seen that three No. 00 wires will give practically the same close approximation, and this would re- quire the handling of only one size of wire, which is sometimes greatly to be preferred. Again, the combination just above this one, namely, four No. 1 wires and one No. 2, is also quite close to the desired value ; this combination would be preferable if there are many corners and bends, as the wires are smaller. The largest limit of the cross-sections in this table was taken as 500,000 circular mils, or a little less than four 00 wires. For larger sections, as, for instance, 600,000, select from the table any convenient combination, regardless of cross-section, as, for instance, that of three 00 wires, and subtract its combined section, namely about 400,000, from the 600,000, and then find from the table the best combination to make up this balance of 200,000, as, for instance, one No. 00 and one No. 2 wire. COMPOUNDED WIRES. 29 TABtE OF COMPOUNDED WIRES OF LARGE SECTION. A table of all the possible combinations of numbers 00^ 0, 1 and 2, B. & S. wires having a combined cross-section of less than 500,000 circular mils. It if Il I || il B. & S. (Ameri Gauge Numb* 1 si S if 11 02 |> M jji oo-oo-oo-oo o-o-o-o-o 532316. 527 67O. OO-O-2-2-2 0-2-2-2-2-2 437 732. 437399. O-O-2-2 O-1-1-2 343814. 339295. OO-OO-1-1-2 499919! OO-OO-l-l OO- 1-1-2-2 433 540. 433213. 1-1-1-1 00-00-2 332 53 1! OO-1-1-2-2-2 1-1-2-2-2-2-2 OO-O-O-1-2 O-O-1-2-2-2 499 586. 499 253. 494214. 493881. 1-1-2-2-2-2 OO-O-O-l O-O-1-2-2 0-1-1-1-2 432 88O. 427841. 427508. 422 989. 00-2-2-2 2-2-2-2-2 OO-O-l O- 1-2-2 332 198. 331 865. 322 3O7, 321974. 00-0-1-1-1 0-1-1-1-2-2 0-0-0-0-2 1-1-1-1-1-2 489 695. 489362. 488 509. 484843. 0-0-0-0 1-1-1-1-1 OO-OO-1-2 OO-1-2-2-2 422 136. 418 47O. 416225. 415892. 1-1-1-2 O-O-O OO-O-2 O-2-2-2 317455. 316602. 3O4986. 3O4 653. O-O-O-l-l OO-OO-OO-l OO-OO-1-2-2 OO- 1-2 -2 -2 -2 483 99O. 482931. 482 598. 482265. 1-2-2-2-2-2 OO-O-O-2 O-O-2-2-2 00-0-1-1 415559. 41O52O. 410187. 406001. 00-1-1 1-1-2-2 O-O-l OO-1-2 3OO 467. 3OO 134. 294762. 283 146. 1-2-2-2-2-2-2 00-00-0-0 00-0-0-2-2 0-0-2-2-2-2 481 932. 477226. 476893. 476 560. 0-1-1-2-2 1-1-1-1-2 O-O-O-l OO-OO-OO 405 668. 4O1 149. 4OO296. 399237. 1-2-2-2 O-O-2 O-l-l OO-OO 282813. 277441. 272922. 266 158. 00-0-1-1-2 0-1-1-2-2-2 OO-1-l-l-l 1-1-1-1-2-2 472 374. 472 O41. 467855. 467 522. OO-OO-2-2 OO-2-2-2-2 2-2-2-2-2-2 OO-O-1-2 398 9O4. 398571. 398238. 388 68O. OO-2-2 2-2-2-2 O-1-2 1-1-1 265825. 265492. 255 6O1, 251 O82. O-O-O-1-2 OO-OO-OO-2 OO-OO-2-2-2 OO-2-2-2-2-2 466 669. 465 6 1O. 465277. 464 944. O- 1-2 -2 -2 OO-l-l-l 1-1-1-2-2 0-0-0-2 388347. 384 161. 383828. 382975. 00-0 0-2-2 1-1-2 OO-l 238613. 238280. 233761. 216773. 2-2-2-2-2-2-2 O-O-l-l-l 00-00-0-1 00-0-1-2-2 464611. 462 15O. 455386. 455053. 0-0-1-1 00-00-0 00-0-2-2 O-2-2-2-2 378 456. 371692. 371 359' 371 O26. 1-2-2 OOOO O-O OO-2 21644O. 211 6OO. 211 O68. 199452. O- 1-2 -2 -2 -2 00-1-1-1-2 1-1-1-2-2-2 OO-O-O-O 454720. 450 534. 45O2O1. 449681. 00-1-1-2 1-1-2-2-2 O-O-1-2 O-l-l-l 366 84O. 366 5O7. 361 135. 356616. 2-2-2 O-l O-2 000 199 119, 189228. 171907. 167805. O-O-O-2-2 O-O-1-1-2 O-1-l-l-l OO-OO-O-2 449348. 444829. 44O31O. 438 O65. OO-OO-l OO-1-2-2 1-2-2-2-2 OO-O-O 349852. 349519. 349 186. 344 147. 1-1 1-2 00 2-2 167388. 15O067. 133 O79. 132 746. 30 WIRING COMPUTER. TABLE OF WEIGHT AOT> RESISTANCE OF COPPER WIRE. American or B. & S. Wire Gauge. Decimal Gauge in Mils. - 1 New British Gauge, or Stand- 00 I ard Wire Gauge, March, 1884. Diameter in Mils. (1 mil = .001 inch.) Cross-section in Circular Mils. (Circ. mil = .7854 sq. mil.) Cross-section in Square Mils. (1 sq. in. = 1,000,000 sq. mils.) Pounds per 1000 Feet. tSp.gr. 8.889.) Feet per Pound. Ohms per 1000 Feet. (1 mil-foot 10.605 legal ohms.) Ohms per Pound. Feet per Ohm. K 1 500. 5OO.OO ! 464.OO 460.00 450. OO 432. OO 425.OO 409.64 4OO.OO 375.OO 372.00 25OOOO. 215296. 211 6OO. 2O2 5OO. 186624. 18O626- 1678O5- 16OOOO- 14O625. 138 384. 196350. 169093. 166190. 159043. 146 574. 141 8637 131 790. 125664. 110 450. 108687. 104518. 96211. 95115. 82958. 82887. "824487 70686. 65732. 59828. 59390. 121287 49876. 49087. 42273. 41339. 756.6 651.6 64O.4 612.9 564.8 534.2 507.9 484.2 425.6 418.8 4O2.8 37O.8 366.5 319.7 319.4 1.322 1.535 1.562 1.632 1.770 1.829 1.969 2.065 2.350 2.388 2.483 2.697 3.728 3.128 3.131 .O4242 .O4926 .O5O12 .O5237 .O5683 .O5871 .O632O .O6628 .07542 .O7664 .0000561 .0000756 .0000783 .0000855 .0001006 .0001074" .0001244 .0001369 .0001772 .0001830 .0001979 .0002335 .0002389 .0003141 .0003146 .0003180 .0004326 .0005003 .0006039 .0006127 .0007955 .0008689 .0008971 .001210 .001265 23573. 2O3O1. 19953. 19O94. 17598. 17032. 15823. 15O87. 1326O. 13O49. 17836. 13228. 12778. 11702. 9939. 9310. 8036. 7306. 5643. 5465. 4/0 45O. 5/6 666 425. 4OO. 375. 4/0 666 oo 350. 00 364.80 35O.OO 348.OO 325.OO 324.86 133 O79. 122 5OO. 121 1O4. 105625. 1O5534. 1O4976. 90 000. 83 694. 76 176. 75625. 66373. 63 504. 62 500. 53824. 52 634. 506257 44 944. 41 743. 4O OOO. 86864. 83 1O27 32 4OO. SO 976. 2625O. 256OO. 2O82O. 2O 736. 196OO. 16900. 16510. .07969 .O8657 .O8757 .1O04 .1OO5 12548. 11551. 11419. 996O. 9951. 5054. 4282. 4185. 3184. 3178. "11457" 2312. 1999. 1656. 1632. ^2577" 1151. 1115. 826.8 790.6 731.4 576.4 497.2 456.6 387.8 ~S12JT 299.6 273.8 196.7 187.0 '6' 325 *i' 300. i 324.OO 3OO.OO 289. 3O 276. OO 275.00 257.63 252. OO 25O.OO 232.00 229.42 225.OO 212.00 204.31 2OO.OO 192. OO 181794 18O.OO 176. OO 162. 02 16O.OO 317.7 272.4 253.3 230.5 228.9 20079" 192.2 189.2 162.9 159.3 3.148 3.671 3.948 4.338 4.369 4.978 5.203 5.287 6.139 6.278 .1O1O .1178 .1267 .1392 .14O2 .1598" .167O .1697 .1970 .2015 9899. 8486. 7892. 7183. 7131. 6258. 5988. 5893. 5075. 4963. 2 ~sT 275. 3 4 25O. 3 225. '5' 39 761. 35 299. 32784. 31416. 28953. 25999. 25447. 24328. 20618. 20106. 153.2 136.0 126.3 121.1 111.6 100.2 98.O6 93.75 79.45 77.48 6.527 7.352 7.916 8.260 8.963 -9.982" 10.20 10.67 12.59 12.91 .2O95 .236O .2541 .2651 .2877 .32 O4 .3273 .3424 .4O4O .4143 75094" .5114 .5411 .6275 .6424 76-473" .7365 .7881 .81OO .8765 .001367 .001735 .002011 .002190 .002579 .003198 .003338 .003652 .005085 .005347 4774. 4238. 3936. 3772. 3476. 3121. 3055. 2921. 2475. 2414. ~T963. 1955. 1848. 1594. 1557. 4 2OO. '&' *7' ~5~ iso. 6 ^T 160. 8 144.29 144.OO 14O.OO, 13O.OO 128.49 16351. 16286. 15394. 13273. 12967. 63.01 62.76 59.32 51.15 49.97 15.87 15.93 16.86 19.55 20.01 .008085 .008150 .009121 .01227 .01286. 123.7 122.7 109.6 81.51 77.79 9 ' a' 140. 130. 120. 1O "lY 128.OO 12O.OO 116.00 114.42 11O.OO 16384. 14400. 13456. 13092. 12 1OO. 12868. 11 310. 10568. 10283. 9503. 8495. 8155. 7854. 6648. 6467. -63627 5129. 5027. 4072. 4067. ^8487 3225. 3217. 2827. 2558. 2463. 2029. 1964. 1810. 1609. 49.59 43.58 4O.73 39.63 36.62 32.73 31.42 8O.27 25.62 24.92 20.17 22.95 24.67 25.24 27.31 .01305 .01690 .01935 .02044 .02393 1545. 1358. 1269. 1236. 1141. 76.60 59.18 51.67 48.92 41.78 & no. T2^ 1O4.OO 1O1.9O 100.00 92.OOO 9O.742 10816. 10384. 1OOOO. 8464. 8234. 8 1OO. 653O. 6400. 5184. 5 179. 30.55 31.82 33.04 39.04 40.13 .98O5 .021 .061 .253 .288 .02995 .03250 .03504 .04891 .05168 76535T- .08218 .08555 .1304 .1307 1O2O. 979.1 942.9 798.1 776.4 763.8 615.7 6O3.5 488.8 488.3 462. 387.2 386.2 339.5 3O7.1 295.7 243.5 235.7 217.3 193.1 33.39 20.77 28.54 20.44 19.35 10 100. 13 11 '12 90. 9O.OOO 80.808 80.000 72.000 71.962 24.51 19.76 19.37 15.69 15.67 40.79 50.60 51.63 63.74 63.81 .309 .624 .657 2.O46 2.O48 18.72 12.17 11.69 7.669 7.653 80. 14 16 13 'l4 *15 7O. 7O.OOO 64.O84 64.OOO 60.000 57.068 4900. 4107. 4096. 36OO. 3257. 14.88 12.43 12.40 10.90 9.857 9.491 7.817 7.566 6.973 6.199 67.43 80.46 80.67 91.78 101.5 2.164 2.582 2.589 2.946 3.256 .1459 .2078 .2084 .2704 .3304 6.852 4.813 4.788 3.698 3.027 ~2780T 1.904 1.784 1.515 1.197 'eo. 16 16 17 56.OOO 50.821 50.000 48.000 45.257 3136. 2583. 25OO. 23O4. 2O48. 105.4 127.9 132.2 143.4 161.3 3.382 4.1O6 4.242 4.6O3 5.178 .3646 .5253 .5607 .6601 .8353 50. "l*8 17 According to the Matthiessen Standard suggested by the Committee of the Eng., these resistances are for pure copper wire at 78)4 F. Amer. Inst. of Elect. WEIGHT AND EESISTANCE. 31 i o 02 Decimal Gauge. New British Gauge. Diam. in Mils. Cross-section in Circular Mils. Cross-section in Square Mils. If I i i Ohms per 1000 Feet. Ohms per Pound. Feet per Ohm. Pounds per Ohm. "is" 45. ... 45.OOO 40.303 40.000 36.000 35.891 2025. 1624. 1600. 1296. 1288. 1590. 1276. 1257. 1018. 1012. ~9627l 804.2 802.3 706.9 636.3 6.129 4.916 4.842 3.922 S.899 163.2 203.4 206.5 255.0 256.5 5.237 6.529 6.628 8.183 8.233 .8545 1.325 1.369 2.086 2.112 190.9 153.2 150.9 122.2 121.5 1.170 .7529 .7306 .4793 .4735 T4282 .2992 .2978 .2312 .1873 !l304 .1178 .09468 .07408 40. 19 2O 26 21 357 2*1 35.OOO 32.OOO 31.961 30.000 28.462 1 225. 1024. 1 O22. 9OO.O 81O.1 3.708 3.099 3.O92 2.724 2.452 2.373 2.O46 .944 .743 .542 269.7 322.7 323.5 367.1 407.9 8.657 1O.36 10.38 11.78 13.O9' 2.335 3.342 3.358 4.326 5.339 115.5 96.56 96.33 84.86 76.39 SO. 22 '23 28. 26. 22 28.000 26.000 25.347 24.OOO 22.572 22.OOO 2O.1O1 2O.OOO 18.OOO 17.900 784.0 676. 642.5 576.O 5O9.5 615.8 530.9 504.6 452.4 400.2 42174 488.8 514.3 573.6 648.5 13.53 15.69 16.51 18.41 2O.82 21.91 26.25 26.51 32.73 33.1O 5.701 7.668 8.490 10.56 13.50 73.93 63.74 6O.68 54.31 48. 04 45.64 38. 1O 37.72 SO.55 3O.21 24. 23 24 25 22. 24 484.O 404.1 4OO.O 324.O 32O.4 380.1 317.3 314.2 254.5 251.7 211.2 201.1 199.6 176.7 172.0 158.3 153.9 145.3 132.7 125.5 120.8 113.1 105.7 99.54 95.03 .465 .223 .211 .98O6 .9697 682.7 817.8 826.0 1020. 1031. 14.96 21.47 21.90 33.38 34.13 .06685 .04659 .04566 .02996 .02930 20. 18. 25 26 16.4OO 16.OOO 15.941 15.OOO 14.80O 269.0 256.O 254.1 225.0 219.O .814O .7748 .7690 .6810 .6629 1229. 1291. 1300. 1468. 1508. 39.43 41.43 41.74 47.13 48.42 48.44 53.47 54.27 69.22 73.04 25.36 24.14 23.96 21.22 20.65 .02064 .01870 .01843 .01445 .01369 26 16. 15. 28* 27 14. 2*9 14.196 14.OOO 13.6OO 13.OOO 12.641 12.4OO 12.OOO 11.6OO 11.258 1 l.OOO 2O1.5 196.0 185.0 169. 159.8 144.O 134.6 126.7 121. .6099 .5932 .5598 .5115 .4836 .4654 .4358 .4O73 .3836 .3662 1640. 1686. 1786. 1955. 2068. 2149. 2295. 2456. 2607. 2731. 52.63 54.11 57.34 62.75 66.36 68797" 73.65 78.81 83.68 87.65 86.29 91.21 102.4 122.7 137.2 .148.2 169.0 193.5 218.2 239.3 19.00 18.48 17.44 15.94 15.O7 14.5O 13.58 12.69 11.95 11.41 .01159 .01096 .009763 .008151 .007288 7006747" .005918 .005167 .004584 .004178 28 13. 12. -36" sY . 2{ * 11. 1O.8OO 1O.O25 1O.OOO 9.2OOO 9.OOOO 116.6 1OO.5 1OO.O 84.64 81.OO 91.61 78.94 78.54 66.48 63.62 .353O .3O42 .3O27 .2562 .2451 2833. 3288. 3304. 3904. 4079. 9O.92 1O5.5 1O6.1 125.3 130.9 257.6 346.9 350.4 489.1 534.1 11. OO 9.477 9.429 7.981 7.638 .003883 .002883 .002854 .002044 .001872 SO 1O. 33 34 9. 31 8.9277 8.4OOO 8.OOOO 7.9503 7.6000 7.0800 7.0000 6.8000 6.3049 6.OOOO 79.7O 7O.56 64.OO 63.2O 57.76 62.60 55.42 50.27 49.64 45.36 39.37 38.48 36.32 31.22 28.27 .2412 .2136 .1937 .1913 .1748 4146. 4683. 5163. 5228. 5720. 133.1 150.3 165.7 167.8 183.6 551.6 703.8 855.5 877.1 1050. 7.515 6.653 6.O35 5.96O 5.446 .001813 .001421 .001169 .001140 .0009521 35 *;*32' 8. 36 33 7. 37* 5O.13 49.OO 46.24 39.75 36.00 .1517 .1483 .1399 .12O3 .1O9O 6592." 6743. 7146. 8312. 9178. 211.6 216.4 224.1 266.8 294.6 1395. 1459. 1639. 2218. 2704. 4.727 4.62O 4.36O 3.748 3.395 .0007170 .0006852 .0006102 .0004510 .0003698 .0002836 .0002087 .0001784 .0001515 .0001122 34 *36 6. 38 5.6147 5.2OOO 5.OOOO 4.8OOO 4.4526 31.53 27. 04 25.00 23.04 19.83 24.76 21.24 19.64 18.10 15.57 .O9541 .08 184 .O7566 .06973 .O6OOO 10482. 12220. 13217. 14341. 16666. 336.4 392.2 424.2 46O.3 534.9 547.8 662.8 674.5 818.3 85O.6 3526. 4792. 5607. 6601. 8915. 2.973 2.55O 2.357 2.173 1.869 ' 6*. 39 40 37 38 4. 41 42 4.4OOO 4.OOOO 3.9652 3.6OOO 3.5311 19.36 16.00 15.72 12.96 12.47 1O.24 9.888 9.000 7.840 6.76O 2.'560 1.44O l.OOO 1273. 15.21 12.57 12.35 10.18 9.793 O5859 O4842 .O4758 .O3922 .O3774 17067. 20651. 21015. 25495. 26500. 9349. 13688. 14175. 20863. 22540. 1.826 1.5O9 1.483 1.222 1.176 .0001070 .0000731 .0000706 .0000479 .0000444 43 39 . . . *4O 44 3.2OOO 3.1445 3.0000 2.8000 2.4OOO 2.OOOO 1.6OOO 1.2OOO l.OOOO 35.682 8.042 7.766 7.069 6.158 4.524 37142 2.011 1.131 .7854 1000. 259510. 8329. 1470. 8.329 1470. .O3O99! 32267. .02993! 33416. .02724 36713. .02373! 42146. .01743) 57364. 1O36. 1O73. 1178. 1353. 1841. 33418. 35841. 43260. 57009. 105620. 1T90107 534690. 1689900. 3504100. 2.162 .9656 .9324 .8486 .7393 .5431 .0000299 .0000279 .0000231 .0000175 .0000095 3. 45 46 48 49 6O "a. .O1211 .00775 .OO436 .OO3O3 3.853 l.OOO 1OOO. 32.10 5.665 .O321O 5.665 82604. 129068. 229456. 330416. 259.5 ~1660T 1.000 31.16 176.5 31156. 176.5 2651. 4143. 7366. 1O6O5. 8.329 .3772 .2414 .1358 .0943 12O.1 .0000046 .0000019 .0000006 .0000003 .4626 .03116 31156. 32.10 1.000 .0000321 1.000 1. 18.177 574.82 1O2.98 43.266 3.2566 43.266 33O.4 33O418. 1O6O5. 1872. 1O.61 1872. 32.10 .O321O l.OOO 5.665 1OOO. 5.665 32.10 .0000321 .03116 1.000 31156. 1.000 31.16 31166. 1OOO. 176.5 l.OOO 176.5 32 WIRING COMPUTER. TABLE OF TEMPERATURE CORRECTIONS FOR COPPER WIRE. Instead of using the usual formula for correcting the resistance of copper wire for temperature, the calculation may be very much simplified by finding the mil-foot resistance K in the first column of the accompanying table, corresponding to the given tempera- ture, and using the simple formula R = -~ K, in which R is the required resistance in legal ohms at the given temperature ; L is the length in feet; d is the diameter of the wire in mils, or d 2 the cross-section in circular mils; and K is the mil-foot resistance taken from the table. As this constant contains only two digits, one of which is unity, the calculation is a very simple one. This table is based on the Matthiessen standard suggested by the Committee of the American Institute of Electrical Engineers, namely 9.612 legal ohms for a mil-foot at C. 10.00 10.10 10.20 10.30 50.47 55.15 59.79 15.44 64.40 18.00 10.26 12.86 10.40 ;68.97 20.54 .50 173.51 23.O6 10.50 1O.6O 78.O1 25.56 10.70 82.47 28.04 stance per 1-foot in al Ohms. K. y, *j III ii A II lfl &c3Q 10.80 10.00 86.90 91.31 30.50 32.95 11.00 95.69 35.38 11.10 100.04 37.80 11.20 104.36 40.20 11.3O 108.64 42.58 11. 4O 112.9O 44.95 11.50 117.14 47.3O WEIGHT OF INSULATED WIRE. 33 WEIGHT OF INSULATED WIRE FOR WIRING. FOB COMPUTING THE COST WHEN MAKERS GITE THE PRICES PER POUND INSTEAD OF PER 100. FEET. B. & S. Wire Gauge Numbers. WEIGHTS IN POUNDS PER 100. FEET. B. & S. Wire Gauge Numbers. American Electrical Works. Underwriters Braided Electric Light Line Wire. American Electrical Works. Weather-proof Braided Electric Light Line Wire. Holmes, Booth and Haydens. K. K. Triple-braided. { 1 ri 12.9jl2.1 14.9 17.1 13.9113.1 15.9 14.9 14.0 13.2 ,12.6:11.9' 11.4 10.9! 1O.4 16.0! 1 5.8! 14.9!l4.l'l3.4'l2.7! 12.1111.6 11.0 I I 29.9 26.9 24.422.420.7 19.2 17.9} 16.8' 15.8<14.9;i4.i;i3.4 12.8 '12.2 11.7 31.5 28.4,25.723.621.8 2O.3 18.9117. 7jl6.7 i 15.8J14.9 14.2 13.5 12.91 12.3 27.1 124.923. 02 1.3 19.9 18.7 17. 6J 16. 5i 15.7! 14.9 14.2 13.e' 13.O 29.8 27.4 25.3,23.5,2 1.9,20.5 19.3 18.2J17.3l 16.4 15.6 14.9J 14.3 32.629.8 27.6 25.e'23. 9 22. 421. 1'19.9'l8. 9 17.9'l7.1 16.3 15.6 36.5 32.8 39.8 43.1 49.7 53.1 35 8 38. 8 135.3 32.3 29.9;27.7 25.9 24:322.8 21. 6 20. 4 19.418.5 17:e! 16.9 46.4 41.8 '38. OI34.8 32. li29. 9 27.9 26.1 24.6 23.2 22. 2O.9 19.9 19. 1 18.2 44.8 |4O.7 37.3 34.4 32. 29.9 28. 26.3 24.9 23.6 22.4 21.3 2O.4 19.5 47.8 43.439.8J36.7J34.2.31.8 29.9 28.1 26.5 25.1 23.9 22.7:21.7 2O.8 5O.7 46.1 42.3 39. 36.2 33.8 31. 7J29.9 28.2'26.7 25.4 24.2 23.1 22.1 597 |537 488 44s 4ls 384 35.8 33.6,3.e29.8 2a. 63.O 56.7|51.5 47.2 43.6 40. 5 37.8 35.433.431.529.9 28.427.O25 8 24.7 66.3!59.7!54.3 49.7 45.942.639.8 37.3 35.1 33.2 31.4 29.8 28.4 27 1 26.O 69.6J62.7 65.6 79.6 82.9 91.2 82.1 99.5 89.5 1O8. 116. 124. 133. 141. 149. 158 166. 174. 199. 2O7. 216. 71.6 74.6 112. 119. 127. 134. 142. 28.5 57.0 52.2 48.2 44.8 41.8:39.2 36.9 34.8 33.O 31.3,29.8|28.5 59.7 54.7 50.5 46.9'43.8 41. OS38.6'36. 5 34.6-32.S!31.3 29.8 62.457.2|52.8 49.0 45.8 42.9 4O.4 38. Ij36.1 ;34.3:32. 731.21 29.8 65.1 59.7 55.1 51.2 47.7 44.8 42.1 39.8 37.7 35.8 34.1 ; 32.6i 31. 1 67.8|62.2 57.4 53.3 49.7 45.6 43.9i41.~ " 74.668.463.1 58.6 54.7 51.3 48.3,45.6,43 .5 39.3 37.3 35.5 33. 9| 32.4 .6J43.2 41.0,39.1 37.3 35.7 81.4'74.6'68.9 64.O 59.7'55.9 52.7149.7 47. l ! 44.8'42.6;4O.7l 38.9 97. 88.2 8O.8 74.6 69.3 64.6 6O.6 57. 1 53.9I51.O 48.5 46.2 44 1142.2 1O5. 94.9 87.O 8O.3J74.6 69.6 ; 65.3 61.4 58. 55. 52.2 49.7:47.5; 45.4 1O2. |93.2 86.1179. 9J74.6 69.9 65.8 62.2 58.9 55.9 53.3 50. 9 48.6 1O9.!99.5:91.8|85.2 79.6 74.6 7O.2, 66.3 62.8j59.7|56.8 | 54.2 51.9 1 15. lO6.i97.6 9O.6 84.5 79.3 74.6 7O.5'66.8 63.4 6O.4i57.6 55.1 122. 1112. 11O3. 95.9 89.583.9 79. 74.6 7O.7 67.1 63.9 61. : 58.4 129. !ll8. 1O9.J1O1. 94.5 88.6 83.4 78.7 74.6 7O.9 67.564.4 61.6 136.: 124.' 1 15.I1O7. 99.5 93.2 87.8 82.9 78.5 74.6 71. 67.8! 64.9 142. 131. J121. 1112. 1O4. 97.9,92.1,87.1i82 478.474.6,71.2,68.1 .1126. 117. 1O9.! 149. 137.1126. |117.|lO9.!lO3. 96. 591. 2|86. 482.1 78.2 74.6J 71.3 1 56.| 143. 132. : 123.1 114. 1O7. 163.1149. 138. ! 128. 1 19.il 12. 172. 179 187J170. 155. 144J130. 124. 117! 194. J176. 162. 149.! 209. 224. 239. 254. 16O. 19O. 174.! 2O4. 187. 172. 217. 199.1184. 231. 211.;i95 244.l224.i207. 45 1 50 139. ,129. ,121. 149. 139J131 16O. 149.J14O. 171J159.J149. 181. 169. 159. 192. '179. 168. 1O1. 95.3,90.3 85.8 81.7 78. 74.6 1O5. 99.5 94.2 89.5 85.2 81.41 77.8 11O..1O4. 98.2 93.388.884.8:81.1 1 14.1 1O8., 1 02. 97.0,92.4 88.2; 84.3 140. 149. 158. 116.I11O. 124.1118. 132.J126. 141. 134. 149. 141. 257.;236. 218. 2O3. 189. 177. 167. 158. 271. 249. 23O. 213.: 199. 187. 176. 165. 298. 274. 253. 235. 219. 12O5. 193. '182. 339. 311.|287. 267. 249. 233. 22O.I2O7. 4O7. 373. 344. 32O. 299. 23O. 263. 249. 55 I 60 I 65 | 70 I 75 I 80 85 90 104.99.594.9190.8 107. 97.3 149. 142. 135. 129. 123 149. 142.H36. 13O. 164. 156.S149.' 143. 196. 187.1178. 17O.I 162. 236.224.213.204. 195. 100 I 105 I 110 115 Copyright, 1891, by CARL HERING. HORSE-POWER TABLE. 37 HORSE-POWER EQUIVALENTS IN VOLTS AND AMPERES. Horse Powe VOLTS. Horse Power 120 130 140 150 160 170 180 190 200 210 220 230 240 250 .1 .622 .574 .533 .497 .466 .439 .414 .393 .373 .355 .339 .324 .311 .298 .1 .15 .932 .861 .799 .746 .699 .658 .622 .589 .560 .533 .509 .487 .466 .448 .15 .2 1.24 1.15 1.07 .995 .932 .878 .829 .7851.746 .711 .678 .649 .622 .597 .2 .25 1.55 1.44 1.33 1.24 1.17 1.1O 1.O4 .982 .932 .888 .848 .811 .777 .746 .25 .3 1.87 1.72 1.6O 1.49 1.4O 1.32 1.24 1.18 1.12 1.O7 1.O2 .973 .932 .895 .3 .35 2.18 2.O1 1.87 1.74 1.63 1.54 1.45 1.37 1.30 1.24 1.19 1.14 1.09 .04 .35 .4 2.49 2.3O 2.13 1.99 1.87 1.76 1.66 1.57 1.49 1.42 1.36 1.3O 1.24 .19 .4 .45 2.80 2.58 2.4O 2.24 2.1O 1.98 1.87 1.77 1.68 1.6O 1.53 1.46 1.40 .34 .45 .5 3.11 2.87 2.66 2.49 2.33 2.19 2.07 1.96 1.87 1.78 1.7O 1.62 1.55 .49 .5 .55 3.42 3.16 2.93 2.74 2.56 2.41 2.28 2.16 2.O5 1.95 1.87 1.78 1.71 .64 .55 .6 3.73 3.44 3.20 2.98 2.80 2.63 2.49 2.36 2.24 2.13 2.03 1.95 1.87 1.79 .6 .65 4.O4 3.73 3.46 3.23 3.O3 2.85 2.69 2.55 2.43 2.31 2.2O 2.11 2. 02 1.94 .65 .7 4.35 4.O4 3.73 3.48 3.26 3.O7 2.9O 2.75 2.61 2.49 2.37 2.27 2.18 2.O9 .7 .75 4.66 4.3O 4.OO 3.73 3.5O 3.29 3.11 2.94 2.80 2.66 2.54 2.43 2.33 2.24 .75 .8 4.97 4.59 4.26 3.98 3.73 3.51 3.32 3.14 2.98 2.84 2.71 2.6O 2.49 2.39 .8 .85 5.29 4.88 4.53 4.23 3.96 3.73 3.52 3.34 3.17 3.O2 2.88 2.76 2.64 2.54 .85 .9 5.60 5.16 4.8O 4.48 4.2O 3.95 3.73 3.53 3.36 3. 2O 3.05 2.92 2.80 2.69 .9 .05 5.91 5.45 5.06 4.72 4.43 4.17 3.94 3.73 3.54 3.38 3.22 3.08 2.95 2.83 .95 1. 6.22 5.74 5.33 4.97 4.66 4.39 4.14 3.93 3.73 3.55 3.39 3.24 3.11 2.98 1. 1.1 6.84 6.31 5.86 5.47 5.13 4.83 4.56 4.32 4.1O 3.91 3.73 3.57 3.42 3.28 1.1 1.2 7.46 6.89 6.39 5.97 5.6O 5.27 4.97 4.71 4.48 4.26 4.O7 3.89 3.73 3.58 .2 1.3 8. OS 7.46 6.93 6.46 6.O6 5.71 5.39 5.1O 4.85 4.62 4.41 4.22 4.O4 3.88 .3 1.4 8.70 8. OS 7.46 6.96 6.53 6.14 5.80 5.5O 5.22 4.97 4.75 4.54 4.35 4.18 .4 1.5 9.32 8.61 7.99 7.46 6.99 6.58 6.22 5-89 5.6O 5.33 5.O9 4.87 4.66 4.48 .5 1.6 9.95 9.18 8.52 7.96 7.46 7. 02 6.63 6.28 5.97 5.68 5.43 5.19 4.97 4.77 .6 1.7 1O.6 9.75 9.O6 8.45 7.92 7.46 7.O5 6.68 6.34 6.O4 5.77 5.51 5.28 5.O7 .7 1.8 11.2 1O.3 9.59 8.95 8.39 7.90 7.46 7.O7 6.71 6.4O 6.11 5.84 5.19 5.37 .8 1.9 11.8 1O.9 1O.1 9.45 8.86 8.34 7.87 7.46 7.09 6.75 6.44 6.16 5.91 5.67 .9 2. 12.4 11.5 1O.7 9.95 9.32 8.78 8.29 7.85 7.46 7.11 6.78 6.49 6.22 5.97 2. 2.2 13.7 12.6 11.7 1O.9 10.3 9.65 9.12 8.64 8. 2O 7.82 7.46 7.14 6.84 6.56 2.2 2.4 14.9 13.8 12.8 11.9 11.2 10.5 9.95 9.42 8.95 8.52 8.14 7.78 7.46 7.16 2.4 2.6 16.2 14.9 13.9 12.9 12.1 11.4 1O.8 1O.2 9.7O 9.24 8.82 8.43 8. OS 7.76 2.6 2.8 17.4 16.1 14.9 13.9 13.1 12.3 11.6 11.0 1O.4 9.95 9.49 9.O8 8.7O 8.36 2.8 3. 18.7 17.2 16. 14.9 14.0 13.2 12.4 11.8 11.2 1O.7 1O.2 9.73 9.32 8.95 3. 3.2 19.9 18.4 17.1 15.9 14.9 14.0 13.3 12.6 11.9 11.4 10.9 1O.4 9.95 9.55 3.2 3.4 21.1 19.5 18.1 16.9 15.9 14.9 14.1 13.4 12.7 12.1 11.5 11.0 10.6 1O.1 3.4 3.6 22.4 20.7 19.2 17.9 16.8 15.8 14.9 14.1 13.4 12.8 12.2 11.7 11.2 1O.7 3.6 3.8 23.6 21.8 20.2 18.9 17.7 16.7 15.8 14.9 14.2 13.5 12.9 12.3 11.8 11.3 3.8 4. 24.9 23. 21.3 19.9 18.7 17.6 16.6 15.7 14.9 14.2 13.6 13. 12.4 11.9 4. 4.2 25.1 24.1 22.4 2O.9 19.6 18.4 17.4 16.5 15.7 14.9 14.2 13.6 13.1 12.5 4.2 4.4 27.4 25.2 23.5 21.9 2O.5 19.3 18.2 17.3 16.4 15.6 14.9 14.3 13.7 13.1 4.4 4.6 28.6 26.4 24.5 22.9 21.5 20.2 19.1 18.1 17.2 16.3 15.6 14.9 14.3 13.7 4.6 4.8 29.9 27.6 25.6 23.9 22.4 21.1 19.9 18.8 17.9 17.1 16.3 15.6 14.9 14.3 4.8 5. 31.1 28.7 26.6 24.9 23.3 21.9 20.7 19.6 18.7 17.8 17.0 16.2 15.5 14.9 5. 6.5 34.2 31.6 29.3 27.4 25.6 24.1 22.8 21.6 2O.5 19.5 18.7 17.8 17.1 16.4 5.5 e. 37.3 34.4 32. 29.8 28.O 26.3 24.9 23.6 22.4 21.3 20.3 19.5 18.7 17.9 6. 6.5 4O.4 37.3 34.6 32.3 3O.3 28.5 26.9 25.5 24.3 23.1 22. 21.1 2O.2 19.4 6.5 7. 43.5 4O.2 37.3 34.8 32.6 3O.7 29. 27.5 26.1 24.9 23.7 22.7 21.8 2O.9 7. 7.5 46.6 43. 4O.O 37.3 35.O 32.9 31.1 29.4 28. 26.6 25.4 24.3 23.3 22.4 7.5 8. 49.7 45.9 42.6 39.8 37.3 35.1 33.2 31.4 29.8 28.4 27.1 26. 24.9 23.9 8. 8.5 52.9 48.8 45.3 42.3 39.6 37.3 35.2 33.4 31.7 3O.2 28.8 27.6 26.4 25.4 8.5 9. 56. 51.6 48. 44.8 42. 39.5 37.3 35.3 33.6 32. SO. 5 29.2 28.0 26.9 0. 9.5 59.1 54.5 5O.6 47.2 44.3 41.7 39.4 37.3 35.4 33.8 32.2 30.8 29.5 28.3 9.5 10. 62.2 57.4 53.3 49.7 46.6 43.9 41.4 39.3 37.3 35.5 33.9 32.4 31.1 29.8 10. 10.5 65.3 60.3 56.O 52.2 49.0 46.1 43.5 41.2 39.2 37.3 35.6 34.1 32.6 31.3 1O.5 11. 68.4 63.1 58.6 54.7 51.3 48.3 45.6 43.2 41.O 39.1 37.3 35.7 34.2 32.8 11. 11.5 71.5 66.0 61.3 57.2 53.6 5O.5 47.7 45.2 42.9 4O.9 39.O 37.3 35.7 34.3 11.5 12. 74.6 68.9 63.9 59.7 56. 52.7 49.7 47.1 44.8 42.6 4O.7 38.9 37.3 35.8 12. 12.5 77.7 71.7 65.6 62'. 2 58.3 54.9 51.8 49.1 46.6 44.4 42.4 40.5 38.9 37.3 12.5 13. 8O.8 74.6 69.3 64.6 6O.6 57.1 53.9 51.0 48.5 46.2 44.1 42.2 40.4 38.8 13. 14. 15. 87.0 93.2 8O.3 86.1 74.6 79.9 69.6 74.6 65.3 69.9 61.4 65.8 58.O 62.2 55.0 58.9 52.2 56.01 5s!sl 47.5 5O.9 45.4 48.7 43.5 46.6 41.8 44.8 14. 15. 16. 99.5 91.8 85.2 79.6 74.6 7O.2 66.3 62.8 59.7 56.8154.3 51.9 49.7 47.7 16. 17. 1O6. 97.5 9O.6 84.5 79.2 74.6 70.5 66.8 63.4 6O.4 57.7 55.1 52.8 50.7 17. 18. 112. 1O3. 95.9 89.5 83.9 79.0 74.6 7O.7 67.1 64.O 61.1 58.4 51.9 53.7 18. 19. 118. 1O9. 1O1. 94.5 88.6 83.4 78.7 74.6 7O.9 67.5 64.4 61.6 59.1 56.7 19. 2O. 124. 115. 1O7. 99.5 93.2 87.8 82.9 78.5 74.6 71.1 67.8 64.9 62.2 59.7 2O. 22. 137. 126. 117. 109. 103. 96.5 91.2 86.4 82. 78.2 74.6 71.4 68.4 65.6 22. 25. 155. 144. 133. 124. 117. 110. 104. 98.2 93.2 88.8 84.8 81.1 77.7 74.6 25. SO. 187. 172. 16O. 149. 14O. 132. 124. 118. 112. 1O7. 1O2. 97.3 93.2 89.5 SO. 120 ~130 140 7so~ 160 170 180 190 200 210 220 230 240 "250 Copyright, 1891, by CARI, HERING. WIRING COMPUTER. WIRING TABLES. The following set of five tables will be found very convenient for a special and limited class of work. They give the distances in feet up to 1,000, to which each size of wire of the B. & S. gauge will carry any given number of lamps at stated losses. Usually such tables are arranged differently, the sizes of wire being given for each number of lamp at regularly increasing distances. By the present arrangement, however, a table of the same size will cover a very much greater range of values ; and, as it gives actual values instead of approximate ones, it is even more accurate, not- withstanding its increased range. It is also more convenient to use, because instead of following two rows of figures to their inter- section, one lirie of figures is followed around a corner, which, for rapid work and a condensed table, is less confusing. Such tables are necessarily limited to special lamps and losses. The values assumed in the following set have been chosen so as to cover as wide a range as possible, and to suit the usual lamps, voltages and losses. For lamps of slightly different currents than those assumed, it need be remembered merely, that if the current is slightly greater, the distances must be taken slightly less than those given, and vice versa. For half the losses given, take half the distances, or better, take the distances for double the number <3f lamps. Although calculated for five special cases, these tables may be used also for quite a number of other lamps, voltages and losses. These have all been classified in the index on the opposite page to facilitate finding which table to use. It should be distinctly understood that these tables are not to be used for successive parts of branched circuits, unless the loss is understood to be for that part only. For instance, suppose the loss in a building is 2 per cent, and a certain circuit branches into two, say at one-fourth of the distance to the lamps, it is not correct to find the size of the first part for a two per cent, loss, and then the sizes of the second parts for a 2 per cent, loss, as this would give a total loss of 4 per cent. But if the loss on the first part be taken as, say \ per cent., and that on the second parts, the remaining \\ per cent., then the tables may be used for each part separately. This error has been made frequently by presumably reliable wiremen. WIRING TABLES. 39 INDEX TO WIRING TABLES. TWO WIRE SYSTEM. Fora 50 volt lamp, taking 1.1 amperes. 50 " ill 50 " 1. 50 " 1. " 50 " 1. " Loss 2.2 " 4.4 " 9.6 " 2. " 4. " 8.8 56 or 1.1 volts, use table No. 1. 2.2 " 2. 4.8 3. 1. " 1. 2. " " 2. 4.4 " " 3. For a 55 volt lamp, taking 1.1 amperes. 55 " l!l " 55 " 1. " 55 " 1. " 55 " 1. " Loss 2. ** 4. " 8.8 " 1.8 " 3.6 " 8. or .75 volts, use table No. 1. 1.5 2. 3.3 " 3. 6.6 ' " 4. For a 75 volt lamp, taking .6 amperes. 75 " !6 " 75 " .6 " Loss .8 " 1.6 " 3.5 " 7. % or .6 volts, use table No. 1. 1.2 ' 2. 2.64 " 3. 5.3 (approx.) " 4. For a 100 volt lamp, taking .5 amperes. 100 " .5 " 100 " .5 " 100 " .5 " 100 " .5 " Loss .5 ** 1* " 2.2 " 4.4 " 8.8 % or .5 volts, use table No. 1. 2 " " 3! 4.4 " " 4. 8.8 " " 5. For a 110 volt lamp, taking .5 amperes. 110 ' .5 f ' 110 " .5 " 110 " .5 " 110 " .5 " Loss .45 " .9 " 2. " 4. ' 8. >c3Scs55S3 es IPllflfJflfS S & ^13333333 w, I i^^^^^^lll d b ft 8 ^ H ffaftaaacxo, S glflllJtSIJ 1 1 11111111 1 _ 2:3!3SSS 3 iH .^^ eScjeeeaesaaca f i CO 00 *' W