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Full text of "Universal wiring computer : for determining the size of wires for incandescent electric lamp leads and for distribution in general, without calculation, formulæ or knowledge of mathematics : with some notes on wiring, and a set of auxiliary tables"

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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. 



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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- 
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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 





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1.4 1.6 1.8 

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2. 2.4 



. 8. 10. 
Copyright, 1891, 



50 100 



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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<xls;and general "Jriits, see text. 



(Chart ^B:) 



HERING. 



240 260 300 350 400 600 700 Lamps 




6. 8. NX 

Copyright, 1891, 1 



10 



70 




9876 5 



2 1 O 

B. & S. Gauge Numbers. 



MANY LAMPS AT SHORT DISTANCES. 

5 Rule for using the chart: 

| Follow the general direction of the broken line and the arrows, from 

^ one set of diagonals to the next. 

Hi, EXAMPLE : What size wire is required for 100 lamps of .775 amperes each, at 50 feet, for 

| a loss of 2 volte? 

SOLUTION : Starting with the current for 1 lamp, .775 amperes (see scale below center), 
2 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 100 lamps ; thence to the right to 
<i the diagonal representing 50 feet, and from here down to the scale of the circular mils 
cr 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, abbj-evjated^metho^s and ge,ne.ral~bints, see text. 

(dwi icf 

ARL BERING. 




Copyright, 1891, b\ 




RL HERING. 



(Chart D.) 



DISTRIBUTION OF INCANDESCENT LAMP 
LEADS. 



IN the ideal system of wiring for incandescent lamps (or 
motors) in multiple arc, there are two requirements, assuming 
that the potential is kept constant at the source : First, that each 
lamp should have the same potential at its socket as all the other 
lamps, when all are burning at once ; secondly, that this potential 
should remain constant at each lamp, when the other lamps are 
turned off. In some cases, as for factories, street lights, store 
lights, etc., only the first requirement need be complied with ; in 
other cases, as in dwellings, theaters, etc., both conditions must 
be provided for. The second condition is the one most difficult to 
provide for, and it necessarily includes the first. A number of 
systems of running the leads will comply with the first condition, 
but to meet the second condition there is only one ideal system. 

In general, it would be quite impracticable to comply strictly 
with either of these conditions, and therefore a slight margin of 
variation at the different lamps is usually allowed ; the amount of 
such allowable variation, being necessarily different for different 
conditions, must be chosen by the judgment of the engineer. This 
variation is due to the different losses in potential in the leads to 
the different lamps. This variation is, therefore, not identical 
with the loss in the leads, but it is the differences between these 
losses when the losses are not precisely the same to all lamps. 

The amount of wire used increases very rapidly as the allow- 
able loss is diminished ; for a 1 per cent, loss, for instance, the 
amount of wire by weight is double what it would be for a 2 per 
cent. loss. On the other hand, if the lamps must be capable of 
being turned off one by one, the life of the lamps in the general 
systems will diminish rapidly as this allowable loss is increased, 
because the unavoidable differences between the losses to different 
lamps, that is, the variation, increases. It is, therefore, a choice 
between two evils. As the conditions are quite different in the 

(9) 



10 WIRING COMPUTER. 

case when the lamps may be turned off one by one, than when 
they always burn together, the two cases must be considered sepa- 
rately and should not be confounded with each other ; the former, 
of course, includes the latter, and is, therefore, merely an addi- 
tional condition to the latter. 

The case in which all the lamps are either burning or turned 
off together, is by far the simpler of the two. In the simple case 
shown' in Fig. 1, the difference between the potential at the nearest 

FIG. 1. 



000000000000 

lamp and that at the farthest, is merely the amount lost in the 
length of wire between the two lamps, and it is entirely independ- 
ent of the amount lost between the dynamo (or center of distri- 
bution) and the first lamp ; this latter loss may, therefore, be made 
as great as desired, as far as the lamps are concerned. In this 
case, therefore, the loss from the dynamo to the first lamp may be 
made anything that is desired, but the wire between the first and 
last lamp must be so large that the loss on that portion does not 
exceed the allowable variation for the lamps, say about 1 percent.; 
or at most, 2 per cent. If this portion of the circuit is so long 
that it would require a very large wire, then the lamps are often 
divided into two or more groups, as shown in Fig. 2, each group 



i 



oooooooooooo 



being supplied or fed by a separate set of leads ; these two sepa- 
rate sets of leads must then be calculated for the same loss as 
before between the dynamo and the lamps, thus requiring the 
longer ones to be much thicker than the shorter ones, as shown. 
The choice between the dispositions shown in Figs. 1 and 2 de- 
pends entirely on whether the wire between the first and the last 
lamp must be so thick, owing to the allowable difference between 
the lamps, that it would be cheaper to divide the leads to dynamo 
into two parts ; this can be determined only by calculating both 
cases. In Fig. 1 it might, under special circumstances, be quite 



DISTRIBUTION OF INCANDESCENT LAMP LEADS. 11 

rational to connect the lamps by a much thicker wire than that 
leading to the dynamo, even though the latter carries a greater 
current. The disposition shown in Fig. 2, of running separate 
sets of leads to different groups of lamps, applies equally well to 
groups of lamps in different directions from the center of distri- 
bution, and in this sense it is one of the most frequent and best 
systems of distribution. 

Another system, but applicable only in special cases, is that 
shown in Fig. 3, in which the two leads from the dynamo divide, 

FIG. 3. 



one going in one direction around a rectangle, and the other going 
in the reverse direction. No matter what the loss or the size of 
the wire, all the lamps between this pair of leads will have the 
same potential, provided the positive and negative leads are both 
of the same size, and provided all the lamps are turned on and 
off together ; if the lamps are turned off one by one, the potential 
will no longer be constant. 

To recapitulate, it will be seen that when the lamps of a group 
are all turned on or off together, and not individually, the distri- 
bution is simple, requiring only that the difference between the 
potential at the nearest and the farthest lamp on the same leads 
shall not exceed the allowable variation of 1, 2 or even 3 per cent, 
(in which case the lamps are entirely independent of the loss be- 
tween them and the dynamo or center of distribution), and that if 
there are a number of such groups connected to the same dynamo 
or center, the loss from dynamo to lamp must be the same for each 
group. In the latter case the groups will be entirely independent 
of each other, and may be turned off or on as individual groups, 
provided their leads do not join those of any other group on their 
way to the dynamo. In other words, groups having independent 
connections to the dynamo are independent of each other, and 



12 WIRING COMPUTER. 

may be turned off or on as groups. It is assumed, of course, that 
the dynamo is self-regulating. 

Taking up the other case, in which the individual lamps are to 
be turned off and on, the problem is quite a different one. Refer- 
ring again to Fig. 1, the loss of potential from each lamp to the 
dynamo or source, depends on the total current in the common 
leads and on the resistance of these leads ; these losses, therefore, 
remain constant only as long as the total current is constant ; if 
one lamp is turned off, the total current becomes less, and, there- 
fore, the loss to each remaining lamp becomes less, and vice versa. 
Finally, if all but one of the many lamps are turned off, the loss 
in the leads will be very small, and, therefore, the potential at the 
last remaining lamp will be increased accordingly. Each individ- 
ual lamp is, therefore, dependent not only on the others, but also 
on the total loss of potential between it and the dynamo. It is in 
the latter feature that this case differs entirely from the first case 
described above, in which they are all turned off or on together. 
For independent lights the loss between them and the dynamo 
must, therefore, be made as small as practicable, as it affects the 
steadiness and life of the lamps. For this reason it requires, in 
general, relatively thicker wire for independent lamps than for 
groups, provided the distance to the dynamo is sufficiently great 
to make a difference. 

Suppose, in Fig. 1, there are 100 lamps and the loss from the 
dynamo to the first lamp is four volts when all are burning ; then 
if all but one are turned off, the voltage of that one will be about 
four volts in excess of what it should be. In order to save the 
lamps from part of this strain, the voltage of the dynamo may be 
so chosen that when all are burning they will be two volts below 
the normal, and when only one is burning it will be two volts 
above, the difference remaining, as before, four volts. If, as in a 
dwelling, the full number of lights burning is the exception, and 
a few lights the rule, then the potential at the dynamos may be 
chosen so that it is the proper amount at the lamps when the aver- 
age number is turned on. 

As the potential at the lamp depends on the total current in 
the leads, it follows that the ideally perfect system of independent 
lamps is to have a separate pair of leads for each lamp back to 
the dynamo (or center of distribution). Each pair of leads is then 
calculated so as to have the required loss for its lamp. Such an 



DISTRIBUTION OF INCANDESCENT LAMP LEADS. 13 

ideal system is, however, not practicable, as a rule, but the general 
rule may be laid down, that the nearer a system approaches to 
this ideal, the better it is. For instance, comparing Figs. 1 and 2, 
in each of which there are twelve lamps, the second approaches 
more nearly to the perfect system, and the lamps in Fig. 2 are 
subjected to only half as great a variation *in potential as those in 
Fig. 1, when all but one are turned off. It follows from this rule 
that the distribution is better, the more a circuit is branched, the 
nearer such branch connections are to the dynamo, and the larger 
the number of independent leads to the dynamo. Such distribu- 
tion is better, not only because the lamps are subjected to less 
variation of potential, but for the same allowable variation of, say 
2 per cent, at the lamp, the total loss from the dynamo to the 
lamps may be chosen much greater than in other systems and 
thereby saving wire, for it is evident that in the ideal system the 
loss from the dynamo to the lamps may be made anything de- 
sired, without making the lamps dependent on each other ; their 
dependence on each other varies with and is proportioned to, the 
number of lamps on one wire, and the distance from the dynamo 
to the junction of their individual wires. 

It is sometimes thought that the ideal system may be carried 
out by calculating the leads to each lamp or groups of lamps sep- 
arately and then bunching all the wires running parallel into one 
common wire having a cross-section equal to the sum of all the 
smaller wires combined. But this is an error and may result in a 
worse distribution than if it had been calculated on the usual 
plan. As soon as two wires are metallically connected they become 
one and the same wire from there to the dynamo. 

To recapitulate : When the lamps are to be cut off independ- 
ently they are dependent on each other and on the loss of potential 
between them and the dynamo in so far as they are connected to 
common leads. The leads should therefore be split up as much as 
practicable, and the total loss should be divided so as to have the 
greater part in the small individual branch wires, and the smaller 
part in the larger main wires. 

To calculate the wires for a building with independent lamps, 
lay them out so as to approach as much as practicable to the 
best distribution as described above, making common mains as 
short as possible, and individual branch wires as great a propor- 
tion of the whole as possible; then determine on the total loss, for 



14 WIRING COMPUTER. 

instance, four volts, and divide it amongst the leads so as to have 
as small a part as practicable (say one volt) on the common main, 
and the other part (three volts) again divided, if necessary, on the 
distributing branch wires. Calculate the size of each wire from 
the number of lamps supplied by it, and from this portion of the 
total loss allowed for that part of the whole lead. The lamps will 
then be dependent on each other only in so far as they are on 
common wires, and to an amount that other lamps effect the loss 
only on this common wire. 

To illustrate some of the points mentioned above by an actual 
(exaggerated) case, suppose the leads for four lamps, a, 6, c, d, Fig. 4, 
be subdivided as shown, and suppose the total loss of 8 volts be 

FIG. 4. 



1 volt 



^ 



* 



oc 



FIG. 5. 



divided into 5, 2 and 1, as indicated, on the separate mains and 
branches ; the relative distances being in the proportions of the 
diagram. The loss is proportionately small on the common mains 
and large on the individual branches. Now, taking any one lamp, 
as a, its voltage will be increased as follows : With b turned off, 
1J volt ; with c or d turned off, J volt ; with c and d both turned 
off, J volt ; with 6, c and d turned off, If volt. This shows that 
lamp a is dependent on the others in proportion as it is on com- 
mon mains with them, and on the loss of volts on the common 
mains, which is small in this case. 

Now, for the sake of comparison, let the four lamps be sup- 
plied by a single pair of mains, as in Fig. 5, with the same loss of 
8 volts. Turning off one lamp increases the voltage of the others 
2 volts ; with two lamps turned off, 4 volts ; and with three lamps 
off, 6 volts. This shows how very great the difference is, namely, 
a maximum of 6 volts in Fig. 5, as compared to If volts in Fig. 4. 



DISTRIBUTION OF INCANDESCENT LAMP LEADS. 15 

The weight of wire in Fig. 4 is only slightly higher, namely, as 
23 to 20. If now the wire in Fig 5 be made larger, so as to have 
the same maximum variation in volts as in Fig. 4, namely, If volt, 
the total loss would have to be 2 volts, and this would increase 
the weight of wire to about three times that in Fig. 4, showing 
the advantage in subdividing the leads, aside from the fact that 
Fig. 4 is a distribution (as the lamps might just as well be at the 
same distance in different directions), while that in Fig. 5 is not. 
The actual figures will, of course, vary greatly under different cir- 
cumstances, and no general statement can be made regarding the 
amount of gain. 

In referring to the dynamo in the above deductions it was 
understood to mean the place from which distribution begins, 
that is, the center of distribution, or the common point at which 
the potential is kept constant. In wiring large buildings or spaces 
it is usual to run a pair of large mains to a central point from 
which distribution begins; this pair of mains, provided it is the 
only one from the dynamo, is not included in the above discus- 
sion, as it is supposed that the dynamo is so regulated as to keep 
a constant potential at the far ends of this pair of mains, that is, 
at the center of distribution ; if the dynamo does not do this, or 
if there is more than one pair of such mains, then it brings the 
center of distribution back to the dynamo, thus making these 
mains part of the distribution. 

A great mistake is often made in supposing that a dynamo can 
keep the potential constant at more than one distant center of dis- 
tribution, without special apparatus at the dynamo. This refers, 
of course, to a system of independent lamps. Suppose all lamps 
are turned on at one center, and only one lamp is on at the other, 
this lamp will be run too high, as the dynamo must be kept at the 
same high potential on account of the lamps on the other center. 
It can be accomplished only in one of two ways, first, approxi- 
mately, by making the loss on the mains very small ; secondly, 
by regulators in each of the original branches from the dynamo. 

It has been suggested to put lower voltage lamps at the most 
distant centers, and higher voltage lamps at the nearer ones, on 
account of the greater loss in the longer mains. It is a question 
Whether this is practicable, for a number of reasons. A lower volt 
lamp requires a greater current and, for this reason alone, a larger 
wire. It is not a good practice to have lamps of differing voltages in 



16 WIRING COMPUTER. 

stock for one and the same building or installation, unless there is 
a reliable person to take charge of their proper placing. 

In the three-wire system there are practically two lamps in 
series, and, therefore, the current need be sent out and back only 
once for every two lamps ; this requires but half the wire (in cross- 
section) otherwise necessary for the same number of lamps. Fur- 
thermore, the loss of volts is divided between two lamps, and it 
can therefore be made twice as great as in the simple system ; this 
halves the quantity of wire again, making the total one-quarter as 
great as for the two-wire system. To carry the current for any 
lamp which may not at the time have another in series with it, a 
third or neutral wire is laid, which, in wiring buildings, is usually 
made the same size as the other two ; this increases the wire by a 
half, making the total three-eighths of that required for the sim- 
ple system. To calculate the leads for the three-wire system, pro- 
ceed as in the simple system and divide the cross-section obtained 
by four, using three wires of this cross-section. The same result 
would, of course, be obtained by using one-quarter the number of 
lamps, or one-quarter the distance, or four times the loss. 



FUSIBLE CUT-OUTS. 



The general principle of safety or fusible cut-outs is that they 
protect from a dangerous excess of current those wires which are 
beyond them, as distinguished from the wires between them and 
the dynamo, which are not protected by the fuses. They should 
therefore always be placed at the beginning of a wire (that is, at 
the end toward the dynamo) and not at the lamp end. Further- 
more, they should be made so small that they protect the smallest 
wire lying beyond them up to the next fuse ; this is not infre- 
quently overlooked, and may be a source of great danger. A thick 
wire is sometimes protected by a large fuse, because it is a thick 
wire, notwithstanding that a small wire is attached to it, unfused ', 
there is always great damage in such cases. It follows, there- 
fore, that wherever the wire changes its size, a fuse should be 
placed, unless the fuse preceding it is small enough for the small- 
est wire beyond it. In general, therefore, a fuse should be placed 
at the beginning of every branch circuit, except as explained. 

If only one side of a circuit is protected by fuses, the building 
is not completely protected, as there are possible cases in which a 
wire might become overheated, as, for instance, when a heavily- 
fused wire and a light unfused wire are both grounded or in con- 
tact. Fuses should, therefore, always be " double-pole." 

It has been suggested to make the fuses of copper wire of a 
certain number of sizes smaller than the size of the wire to be pro- 
tected by it. This would be a very good general rule and guide, 
but the temperature of the fused copper is so very much higher 
than that of lead alloys, that there would be danger of fire caused 
by scattering of this melted copper. 

Fuses should be marked with the current at which they will 
fuse, but as such marks are sometimes very unreliable, even with 
fuses sold by otherwise reliable companies, a careful engineer will 
always test a sample fuse before using them. Some fuses are 
marked with the number of lamps normally supplied by them, 
others with amperes, others with the fusing current, etc.; unless it 
is known what such marks mean, it is not safe to trust them. 

(17) 



WIRING FORMULAE. THEIR DEDUCTION 
AND USE. 



When a current passes through a wire there is a gradual loss 
of voltage along the whole length of the wire. This loss, from 
Ohm's law, is equal to the product of the current and the resist- 
ance, that is, 

E = CR 
Now, the resistance of a wire is equal to 

R= L 10.61 1 
d 2 

in which R is in legal ohms, at about 75 to 80 F. ; L is the length 
of the wire in feet, d is the diameter in mils or d 2 the cross-section 
in circular mils. 

From these two formulae it follows that 
10.61 C L 
E = -dT- 

from which the loss in volts can be determined for any current, 
length and diameter of wire. As the circuit is usually a loop or 
return circuit, it is simpler to use the distance, represented by D 
which is equal to ^ L. Furthermore, as the loss is usually known, 
while the diameter is that which is required, the formula reduces 
to the form 

j > 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 

<j 


A. F. Moore. Weather-proof. 


A. F. Moore. Fire and Weather-proof. 


N. Y. Insulated Wire Co. 
Competition Line Wire. 


N. Y. Insulated Wire Co. 
Other Wires. 


Okonite Electric Light Line Wires. 
Plain Insulation. 


Okonite Electric Light Line Wires. 
Braided Insulation. 


Simplex. 
T Z R Weather-proof. 


Simplex. 
Caoutchouc, Plain Rubber. 


Simplex. 
Caoutchouc with Protective Braids. 


OOOO 

ooo 

00 


1 


Solid 
Solid 
Solid 
Solid 






7O.6 
6O.O 
5O.O 
4O.O 


75. 
65.O 
44.0 
35.0 


73. 
53.7 
42.3 
33.2 


88.7 
65.5 
51.6 
41.7 


40.6 


... 


93.8 
69.2 
56.4 
43.7 


99.0 
71.4 
60.0 
47.3 


74.6 
60.6 
47.7 
38.2 


78.1 
63.3 
50.1 
41.8 


92.6 
8O.9 
67.2 
57.0 


OOOO 
OOO 
00 

o 

1 
1 
2 
2 

3 
3 

4 
4 






45.0 
35.0 


42.5 
33. 


1 
1 

2 
2 

3 
3 
4 
4 


Solid 
Stranded 
Solid 
Stranded 


29.0 


27.O 


31.6 


28.4 


27. 


33.4 


33.3 


tj 


34.5 
36.2 
28.2 
3O.O 


36.7 
38.7 
29.7 
32.5 


31.1 
2.38 


31.4 
33. 
25.5 
26.5 


37.2 
41.2 
29. 
31.9 


24.0 


20. 4 


27.9 


23.5 


22.4 


27.7 


28.6 
















Solid 
Stranded 
Solid 
Stranded 


19.5 


17.7 


24.O 


19.0 


18.0 


22.3 


21.1 


I 



* 


20.6 
24.O 
17.O 
2O.1 


22. 
25.7 
18.4 
21.4 


19.2 
16.8 


20. 3 
22.1 
16.7 
17.1 


24.O 
25.8 
18.8 
19.1 


15.5 


14.0 


15.8 


15.5 


14.7 


18.2 


18.2 
















5 
5 
6 
6 

7 
7 
8 
8 

9 
1O 
11 
12 

13 
14 
15 
16 


Solid 
Stranded 
Solid 
Stranded 


12.5 


11.0 


12.9 


12.5 


11.9 


17.4 


14.3 


) feet and nc 






12.6 
10*. 4 


13.6 
13.8 
1O.7 
11.7 


16.3 

12*. 7 
13.5 


5 
5 
6 
6 

7 
7 
8 
8 

9 
10 
11 
12 

13 
14 
15 
16 

17 
18 
19 
20 


16.3 
11.6 
13.6 


17.7 
12.5 
15.0 


1O.5 


9.5 


1O.9 


1O.2 


9.7 


12. 


11.1 


8.1 












Solid 
Stranded 
Solid 
Stranded 


7.3 


8.3 


8.1 


7.7 


10.3 




and sold by the 1<X 


lo'.e 

7.O 
8.8 

5.6 
5.2 


l'l'.5 
7.6 
9.6 


8.9 


8.5 


1O.2 

8.2 
8.7 

7.0 

5.7 


7.3 


6.5 


7.1 


6.9 


6.6 


8.9 


7.2 


7.6 


7.0 
7.4 


5.5 
5.0 
4.O 
2.9 

2.4 
2.1 
1.7 
1.3 

1.2 
1.0 
.90 
.85 


4.9 
4.5 
3.5 
2.5 

2.1 
1.8 
1.5 
1.3 

1.2 
1.0 
.90 
.85 


5.5 
5.2 
3.95 
3.4O 


5.4 
4.7 


5.1 
4.5 


6.8 
6.0 





Solid 
Solid 
Solid 
Solid 


6.1 
5.6 


6.4 
5.3 


5.9 
4.6 


2.85 


2.6 


3.5 





1 


3.3 


3.8 


3.7 


3.1 


4.2 


Solid 
Solid 
Solid 
Solid 




2.27 


2.00 


1.9 


2.7 






2.4 


2.7 


2.4 


2.1 


2.9 


1.89 


1.3O 


1.25 


1.8 







1.55 


1.86 


1.8 


1.4 


1.9 


17 
18 
19 
2O 


Solid 
Solid 
Solid 
Solid 






1.5O 


1.O5 
.90 
.85 


l.OO 
.85 
.80 


1.4 
1.24 
1.17 






1.10 


1.38 


1.5 


1.0 


1.4 










.95 


1.21 



















34 



WIRING COMPUTER. 



TABIuE OF HEATING LIMITS 

OB 

MAXIMUM SAFE CARRYING CAPACITY 

OF INSULATED WIRES. 

These numbers were calculated from the formula given by the 
Edison Company on their standard tables, namely : max. amp. = 

CITC ' /1 I which reduces to the more convenient form : 
104. J 



.031 J 2 diam* 



The numbers are only approximate, as they depend on the 
nature of the surroundings of the wire, thickness of insulation, 
etc. The temperature given with the formula is 50 C. or 122 F. 



& 

II 


I 


Greatest number of LAMPS of the following different 
currents per lamp : 


lORSE- 

on a 

Ircuit.* 


tl 


*2 


I 


(For the THSKB-WIRI system use double the number of lamps.) 


iP 


21 







.45 


.50 


.55 


.60 


.65 


.70 


.75 


.80 


.90 


1.00 


1.10 


JPl 





0000 


303. 


673 


6O6 


651 


505 


466 


433 


404 


379 


336 


303 


275 


89.3 


oooo 


ooo 


254. 


566 


509 


463 


424 


392 


364 


339 


318 


283 


254 


231 


75.0 


ooo 


oo 


214. 


476 


428 


389 


357 


329 


3O6 


285 


267 


238 


214 


195 


63.1 


oo 


o 


180. 


400 


360 


327 


3OO 


277 


257 


24O 


225 


2OO 


18O 


163 


53. 


o 


1 


151. 


336 


302 


275 


252 


232 


216 


2O1 


189 


168 


151 


137 


44.5 


1 


2 


127. 


282 


254 


231 


212 


195 


181 


169 


159 


141 


127 


115 


37.5 


2 


3 


107. 


237 


213 


194 


178 


164 


152 


142 


133 


119 


1O7 


97 


31.4 


3 


4 


9O. 


2OO 


18O 


163 


15O 


138 


128 


12O 


112 


1OO 


9O 


82 


26.5 


4 


6 


75. 


167 


151 


137 


125 


116 


1O7 


1OO 


94 


84 


75 


68 


22.2 


5 


6 


63. 


14O 


127 


115 


105 


97 


9O 


84 


79 


70 


63 


67 


18.6 


6 


7 


63. 


118 


1O6 


97 


89 


82 


76 


71 


66 


69 


63 


48 


15.7 


7 


8 


45. 




89 


81 


74 


69 


64 


59 


66 


49 


45 


40 


13.2 


8 


9 


37. 


83 


75 


68 


62 


57 


63 


6O 


47 


41 


37 


34 


11.0 


9 


10 


31. 


70 


63 


57 


62 


48 


45 


42 


39 


35 


31 


29 


9.32 


10 


11 


26. 


59 


53 


48 


44 


41 


38 


35 


33 


29 


26 


24 


7.81 


11 


12 


22. 


49 


45 


40 


37 


34 


32 


3O 


28 


25 


22 


20 


6.58 


12 


13 


19. 


42 


38 


34 


31 


29 


27 


25 


23 


21 


19 


17 


5.54 


13 


1/4 


16. 


35 


32 


29 


26 


24 


22 


21 


20 


17 


16 


14 


4.66 


14 


15 


13. 


29 


26 


24 


22 


20 


19 


17 


16 


14 


13 


12 


3.89 


15 


16 


11. 


24 


22 


20 


18 


17 


16 


15 


14 


12 


11 


10 


3.27 


16 


17 


9.4 


21 


19 


17 


16 


14 


13 


12 


11 


10 


9 


8 


2.75 


17 


18 


7.9 


17 


16 


14 


13 


12 


11 


1O 


10 


9 


8 


7 


2.32 


18 


19 


6.6 


14 


13 


12 


11 


10 


9 


8 


8 


7 


6 


6 


1.95 


19 


20 


5.6 


12 


11 


10 


9 


8 


8 


7 


7 


6 


6 


5 


1.63 


2O 


21 


4.7 


10 


9 


8 


8 


7 


6 


6 


6 


6 


4 


4 


1.37 


21 


22 


3.9 


8 


7 


7 


6 


6 


5 


5 


5 


4 


4 


3 


1.15 


22 



* These numbers represent ELECTRICAL HORSE-POWER ; for MECHANICAL HORSE-POWER mul- 
tiply these numbers by the efficiency of the motor. 

Copyright, 1891, by CARL HERINO. 



HORSE-POWER TABLE. 35 



TABLE OF HOKSE-POWER EQUIVALENTS. 

In wiring for motors, the wireman desires to know what cur- 
rent he must wire for, when the horse-power is given. To do this 
he must find the current corresponding to this horse-power. The 
horse-power tables as usually published are not well suited for 
this, as they are arranged for the reverse of this calculation. 
Furthermore, their ranges and the large number of decimals are 
far beyond the limits used by wiremen, and the tables are, there-' 
fore, unnecessarily large and cumbersome. The following table 
has therefore been prepared especially for wiremen, the ranges 
being chosen to cover those with which he has to deal, namely, 
from .1 to 30 H.P. and from 45 to 250 volts. It gives the currents 
in amperes required for different horse-powers at different voltages. 

For horse-powers greater than the limit of the table, find the 
current for J, , or J of this horse-power, and then multiply the 
current obtained by 2, 3, or 4, respectively. For an odd number 
of horse-powers, as 21.5, for instance, add the current for 1.5 to 
that for 20 H.P. 

For two, three, or four times the voltage given in the table, 
divide the current obtained from the table by two, three, or four, 
respectively. 

The figures at the top may be read as amperes if those in the 
body of the table are read as volts. If many determinations are 
to be made for one particular voltage it is recommended to draw 
a red line on each side of that particular column. 

For very large horse-powers, or when greater accuracy is re- 
quired than is given in the table, the calculation should be per- 
formed. The current in amperes is equal to the horse-power mul- 
tiplied by 746 and divided by the voltage. 

These figures are for electrical horse-powers supplied 
to the motor. If the column of horse-powers is to rep- 
resent mechanical horse-powers delivered by the motor, 
then divide the current obtained from the table by the 
efficiency of the motor (in units, thus, 70), and multiply 
by 100, which will give a proportionately greater current. 



36 



WIRING COMPUTER. 



HORSE-POWER EQUIVALENTS IN VOLTS AND AMPERES. 



Horse 
Power 



.1 
.15 
.2 
.25 



.35 

.4 

.45 

.5 

.55 

.6 

.65 

.7 

.75 



.85 

.9 

.95 

'.I 

.2 
.3 
.4 
.5 
.6 

1.7 
1.8 
1.9 



2.4 
2.6 
2.8 



3.4 

3.6 

3.8 

4. 

4.2 

4.4 

4.6 

4.8 

5. 

6.5 



6.5 

7. 

7.5 



8.5 

9. 

9.5 
1O. 
10.5 

11. 

11.5 

12. 

12.5 

13. 

14. 
15. 
16. 
17. 
18. 

19. 
2O. 
22. 
25. 
SO. 



VOLTS. 



50 55 



65 70 I 75 



100 



105 110 115 



4.15 3.73 
4.97 



1.66 1.49 1.36 1.24X15 1.O7|.995 .932 .878 .829 .785 .746 .71OI.678 .649 
2.49 2.24 2. 04 1.87, 17.211. 6O|1. 49 1. 4o|l.32 ! 1.24'1. 18 1.12 1.O7 1.O2 973 
3.32 2.99 2.71!2.492.3O2.13il.99 1.8711. 76'l.65 1.57 1.49 1.42 1 36 1.3O 
3.39 3.11 2.87:2. 67J2. 49 2.33 2.2O 2. 07; 1.96 1.87 1.78 1.7O 1 1 62 
4.O7 3.73 3.44 3.2O 2.99 2.8OJ2.63 2.49 2.36|2.24 2.13 2.O4 1.95 

4.75 4.354.O2 3.73 3.48 3.263.O7 2.9O2.75 ! 2.61 2.49 2 37 2 27 
5.434.97 4.59 4.263.98 3.73 3.51 3.32 3. 14 2.98 2.84 271 2^60 
6.10:5.59 5. 16 4.8O 4.48 4.2O 3.95 3.73 3.53 3.36 3.2O 3.O5 2.92 
6.78|6.22i5.745.33 4.97 4.564.39 4.153.93 3.73 3.55 3.39 3.24 
7.46,6.8416.31:5.86,5.4715.1314.83,4.56,4.32 4.103.91,3.7313.57 

A C** A *%*( . 



5.8O 5.22 
6.63 5.97 

6.71 

7.46 
9.12 8.21 

9.95 8.95 8.14!7.46 ! 6.89'6.405.97i5.59'5.27|4.97l4.71 4.48'4.26'4 O7 ! 3 89 
1O.8;9.7O 8.82 8.O8 7.46 6.93 6.46 6.O6 5.71 5.39 5. 1O 4.85 4.62 4 41 4 22 
1 1.6 ! 1O.5 9.49 8.7O 8.O3 7.46 6.96 6.53 6. 14 5.8O 5.5O 5.22 4.97 4 75 ! 4 54 
1 1.2 1O.2 9.32 8.6l!7.99 7.46 6.99 6.58 6.22 5.89 5.59 5.33 5*09 4 86 
10.9,9.95,9.18 8.52 7.96,7.46 7.O2 6.63 6.28 5.97 5.68 5. 42 5^9 



14.9 
15.8 



18.2 



24.9 
26.5 



i : i 



11.9 

12.7 11.5il0.69.769.06;8.45l7.937.46 ! 7.05'6.68 ! 6.346.04'5.76!5.51 
13.4il2.2jl 1.2 1O.39. 59 8.958. 39 ( 7.9O 7.46 7. 07 6.71 6.39 6.1O 5.84 
14.2-12.9 11.8 1O.91O.1 9.4518.868.34 7.87 7.46 7. 09 6.75 6 44 6.16 
1 4.9 13. 6, 12. 4 11.5 1O.7 9.95 9.32 8.78 8.29 7.85 7.46 7.1O6 78 6 49 
16.4 1 4.9,13.7:12. 6;il. 7110.9.10.3:9. 65 9. 12 8. 64,8.21 7.82 7.46: 7.13 



17.9 
19.4 



23.9 



28.2 '25.4 



21.7 
23.1 



14.9 13.8J12.8I11.9 11.2 1 



16.3 

16.2;14.9 
19.O 17.4 16.O 



20.4 18.7 



17.2 



19.9 18.4 



21.1 19.5 18.1 



1O.5 9.95 9.42 8.95 8.52 ! 8.14' 7.78 
11.411O.8I1O.2 9. 7O 9. 24 8.82 8.43 
12.3! 11.6jll.O 1O.49.95 9. 49I9.O8 
16.O 14.9J14.O 13.2il2.4 11.8ill.2llO.7!lO 2 9.73 



13.9>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. 


<fr or 1.1 volts, use table No. 1. 
2.2 " " 2. 
4.84 3. 
1. " 1. 
2. ' " 2. 
4.4 ' " 3. 


For a 75 volt lamp, taking .75 amperes. 
75 " .75 f ' 
75 " .75 " 
75 " .75 " 


Loss 1. 
" 2. 
" 4.4 
" 8.8 


<f> 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. 


<fc or .5 volts, use table No. 1. 

4.'4 " " 4.' 
8.8 " " 5. 


For a 110 volt lamp, taking .45 amperes. 
110 " .45 f ' 
110 " .45 " 
110 " .45 " 
110 " .45 " 


Loss .41 
" .8 
" 1.8 
" 3.6 
" 7.2 


% or .45 volts, use table No. 1. 
(ap.) .9 " " 2. 
2. (approx.) " 3. 
4. (approx.) " 4. 
8. (approx.) " 5. 



THREE WIRE SYSTEM. 

For a 100 volt lamp, taking .5 amperes. Loss .55 <jo or .55 volts per lamp, use table No. 3. 

100 .5 "' " 1.1 1.1 4. 

100 " _ .5 _ " 2.2 2.2 _ _ R 

For a 110 volt lamp, taking .5 amperes. Loss .5 $ or .55 volts per lamp, use table No. 3. 

' ' 2.2 " " 5.' 



_ 110 " _ .5 " " 2. 

For a 110 volt lamp, taking .45 amperes. Loss .4 

110 .45 fi " .9 

_ 110 " .45 " " 1.8 



or .5 (approx. 

1. (approx. 

2. (approx. 



use table No. 3. 
" 5! 



MOTOR CURRENTS. 



For a 50 volt circuit, and a loss of 2 $ or 1. 
50 " " 4. 2. 

50 " " 8.8 4.4 

50 " 17.6 8.8 

For a 55 volt circuit, and a loss of 1.8 (ap.) 1. 

8 ifti 

65 " " 16. 8.8 

For a 75 volt circuit, and a loss of 1.3 



volt, use table No. 1. 
2. 

" 3. 

" 4. 



volt, use table No. 1. 

2. 

3. 

" 4. 



2.7 
5.9 
11.7 



ap.) 1. 
ap.; 2. 
ap.) 4.4 
ap.) 8.8 



volt, use table No. 1. 

" 3! 

" 4. 



For a 100 volt circuit, and a loss of 1. $ or 1. 
100 " " 2. 2. 

100 " " 4.4 4.4 

100 " " 8.8 8.8 

100 " " 17.6 17.6 



volt, use table No. 1. 

3. 

4. 

" 5. 



For a 110 volt circuit, and a loss of .9 (ap.) 1. 
110 " " 1.8 (ap.) 2. 

110 " " 4. 4.4 

110 " " 8. 8.8 

110 " " 16. 17.6 



volt, use table No. 1. 
** 2. 

3. 

4. 
" 5. 



a 220 volt circuit, and a loss of .9 (ap.) 2. 
220 "2. 4.4 

220 " " 4. 8.8 



volt, use table Nc. 2. 

" 3. 

4. 

** 5. 



40 



WIRING COMPUTER. 



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WIRING "COMPUTED, 






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ThackaraMfg.Co 



and 1^26 Chestnut Street, 



PHILADELPHIA, PA. 



Mantafactuirer of 




Electroliers 

and 

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SPECIAL DESIGNS 
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CHARLES C. KIXG, G. A. HARMOTJNT, 

ANTOINK BOURNOHVILLE. 149 Wabash Ave., Chicago, 111 

ALFRED F. MOORE, 



MANUFACTURER OF 



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of every description. 



200 N. Third St., Philadelphia, Pa. 



THE 




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MANUFACTURERS OF 



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Adopted by the NAVY DEPARTMENT, and in use on all the vessels of 
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W. M. HABIRSHAW, General Manager. 






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UNIVERSITY OF CAUFORNIA LIBRARY 



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