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UNIVERSAL
WIRING COMPUTER

FOR DETERMINING

The Size of Wires for Incandescent Electric

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-

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.

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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.9 1. 1.2 1.5

98 7

B. & S. Gauge Numbers.

FEW LAMPS AT SHORT DISTANCES.

Rule for using the chart:

Follow the general direction of the broken line and the arrows, from
one set of diagonals to the next.

EXAMPLE: What size wire is required for 10 lamps of .775 amperes each, at 50 feet, for
a loss of 1 volt?

SOLUTION : Starting with the current for 1 lamp, .775 amperes (see scale below center),
follow it (see broken line and arrows) to the left, until it intersects the diagonal represent-
ing 1 volt loss ; thence up to the diagonal representing 10 lamps ; thence to the right to
the diagonal representing 50 feet, and from here down to the scale of the circular mils
or gauge numbers, on which the reading is found to be about 8,200 circular mils, or a
No. 11 B. & S. wire.

For a more detailed explanation, abbreviated, raetbods-and gerv?ral5iiots, see text.

ARL IIERING.

12 Lamps 14

18 20 22 24 26 30 35 40 50 60 70 Lamps

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1.4 1.6 1.8

Loss in volts.

2. 2.4

. 8. 10.

50 100

150

200

250 300 Feet 400

500

8 ! 3
2 i o

B. & S. Gauge Numbers.

00

<=" o~

g fe

FEW LAMPS AT

DISTANCES.

Rule for using the chart :

Follow the general direction of the broken line and the arrows, from
one set of diagonals to the next.

EXAMPLE: What size wire is required for 10 lamps of .775 amperes each, at 500 feet, for
a loss of 2 volts?

SOLUTION : Starting with the current for 1 lamp, .775 amperes (see scale below center),
follow it (see broken line and arrows) to the left, until it intersects the diagonal represent-
ing 2 volts loss ; thence up to the diagonal representing 10 lamps ; thence to the right to
the diagonal representing 500 feet, and from here down to the scale of the circular mils
or gauge numbers, on which the reading is found to be about 42,000 circular mils, or a
No. 4 B. & S. wire.

For a more detailed explanation, abbreviated, aeib<xls;and general "Jriits, see text.

(Chart ^B:)

HERING.

240 260 300 350 400 600 700 Lamps

6. 8. NX

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.

RL HERING.

(Chart D.)

DISTRIBUTION OF INCANDESCENT LAMP

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
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

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

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

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

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.

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

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

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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2 2 2 2 2

l

WIRING TABLES.

41

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I

42

WIRING COMPUTER.

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44

WIRING "COMPUTED,

!
|

ifl

sa
3
*

I!

I

ThackaraMfg.Co

and 1^26 Chestnut Street,

Mantafactuirer of

Electroliers

and

Gas Fixtures.

SPECIAL DESIGNS
FOR

Hotels,

Theatres,
Office Buildings

AND

Marine Work.

ALFRED F. MOOSE, Established 182O. WBBTBRN AGKKT,

CHARLES C. KIXG, G. A. HARMOTJNT,

ANTOINK BOURNOHVILLE. 149 Wabash Ave., Chicago, 111

ALFRED F. MOORE,

MANUFACTURER OF

INSULATED

ELECTRIC WIRE,

FLEXIBLE CORDS AND CABLES,

of every description.

200 N. Third St., Philadelphia, Pa.

THE

Runner and Gotta Percty Insulating Co.

MANUFACTURERS OF

RUBBER COVERED WIRE

For Concealed Work, For Electric Railways,

For Underground Work, For Manufactories*

For Public Buildings.

Adopted by the NAVY DEPARTMENT, and in use on all the vessels of
the United States Navy.

Our insulation fulfills all requirements in places demanding the " Beet," and
in that field finds no successful competitors.

Office and Works, Branch Office,

Glenwood, Yonkers, N. Y. 315 Madison Ave., New York.

(Cot. 42d St.)
W. M. HABIRSHAW, General Manager.

m-fff^ym\

^B^^^

465768

UNIVERSITY OF CAUFORNIA LIBRARY

I
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