LAMP TABLE FOR RUBBER COVERED WIRES

Showing the maximum number of 16 candle power 110 to 240 volt lamps in parallel that may be carried by the various sizes of wire without violating the underwriters' rules.

Wire size
B. & S.
gauge
Amperes.3.1.watt lamps.3.5.watt lamps.4.watt lamps.
At 110
volts.
220
V.
At 110
volts.
220
V.
220
V.
230
V.
240
V.
0000210462924412825722754787
000177389778347695608636663
00150330660294589515539562
0127279558249499436456476
1107235470210420367384401
290197396176353309323337
376167334149298261273285
465143286127255223233243
554118237106212185194202
64610120290180158165172
8337214564129113118123
1024521054794828690
121737743366586163
1412265223½47414345
16[3]613..11..202122

Now, according to Ohm's law,

volts = amperes × ohms . . . . (2)

hence, substituting in (2) the value for the resistance in ohms, as obtained in (1):

volts = amperes × feet × 10.8 circular mils

or using the usual symbols

E = I × feet × 10.8 circular mils . . . . (3)

or expressed in words, formula (3) means that the volts lost or drop between the beginning and end of a circuit is equal to the current flowing through the circuit multiplied by the product of the conductors' length in feet multiplied by the resistance of one mil foot of wire, divided by the area of the conductor in circular mils.