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. | ||
| 0000 | 210 | 462 | 924 | 412 | 825 | 722 | 754 | 787 |
| 000 | 177 | 389 | 778 | 347 | 695 | 608 | 636 | 663 |
| 00 | 150 | 330 | 660 | 294 | 589 | 515 | 539 | 562 |
| 0 | 127 | 279 | 558 | 249 | 499 | 436 | 456 | 476 |
| 1 | 107 | 235 | 470 | 210 | 420 | 367 | 384 | 401 |
| 2 | 90 | 197 | 396 | 176 | 353 | 309 | 323 | 337 |
| 3 | 76 | 167 | 334 | 149 | 298 | 261 | 273 | 285 |
| 4 | 65 | 143 | 286 | 127 | 255 | 223 | 233 | 243 |
| 5 | 54 | 118 | 237 | 106 | 212 | 185 | 194 | 202 |
| 6 | 46 | 101 | 202 | 90 | 180 | 158 | 165 | 172 |
| 8 | 33 | 72 | 145 | 64 | 129 | 113 | 118 | 123 |
| 10 | 24 | 52 | 105 | 47 | 94 | 82 | 86 | 90 |
| 12 | 17 | 37 | 74 | 33 | 66 | 58 | 61 | 63 |
| 14 | 12 | 26 | 52 | 23½ | 47 | 41 | 43 | 45 |
| 16[3] | 6 | 13 | .. | 11 | .. | 20 | 21 | 22 |
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.