There are two ways of keeping this loss down. One is by increasing the size of the transmission wires, thus cutting down the resistance in ohms; the other way is by raising the voltage, thus cutting down the per cent loss. For instance, suppose the pressure was 1,100 volts, instead of 110 volts. Five amperes at 1,100 volts pressure, gives the same number of watts, power, as 50 amperes, at 110 volts pressure. Therefore it would be necessary to carry only 5 amperes, at this rate. The loss would be 5 volts, or less than ½ of 1 per cent, as compared with 45 per cent with 110 volts.
Splicing transmission wire
In large generating stations, where individual dynamos frequently generate as much as 20,000 horsepower, and the current must be transmitted over several hundred miles of territory, the voltage is frequently as high as 150,000, with the amperes reduced in proportion. Then the voltage is lowered to a suitable rate, and the amperage raised in proportion, by special machinery, at the point of use.
It is the principle of the C^2R loss, which the farmer must apply in determining the size of wire he is to use in transmitting his current from the generator switchboard to his house or barn. The wire table on page 159, together with the formula to be used in connection with it, reduce the calculations necessary to simple arithmetic. In this table the resistance of the various sizes of wire is computed from the fact that a wire of pure copper 1 foot long, and 1/1000 inch in diameter (equal to one circular mill) offers a resistance of 10.6 ohms to the foot. The principle of the C^2R loss is founded on Ohm's Law, which is explained in Chapter V.
The formula by which the size of transmission wire is determined, for any given distance, and a given number of amperes, is as follows:
In other words, multiply the distance in feet from mill to house by 22, and multiply this product by the number of amperes to be carried. Then divide the product by the number of volts to be lost; and the result will be the diameter of the wire required in circular mills. By referring to the table above, the B. & S. gauge of the wire necessary for transmission, can be found from the nearest corresponding number under the second column, entitled "circular mills area."
COPPER WIRE TABLE
| B.& S. Gauge | Feet per Lb. | Area in circular mills | (R) Ohms per 1,000 feet | Feet per Ohm | (R) Ohms per pound |
| 0000 | 1.561 | 211,600.0 | .04904 | 20,392.90 | .00007653 |
| 000 | 1.969 | 167,805.0 | .06184 | 16,172.10 | .00012169 |
| 00 | 2.482 | 133,079.0 | .07797 | 12,825.40 | .00019438 |
| 0 | 3.130 | 105,534.0 | .09829 | 10,176.40 | .00030734 |
| 1 | 3.947 | 83,694.0 | .12398 | 8,066.00 | .00048920 |
| 2 | 4.977 | 66,373.0 | .15633 | 6,396.70 | .00077784 |
| 3 | 6.276 | 52,634.0 | .19714 | 5,072.50 | .00123700 |
| 4 | 7.914 | 41,742.0 | .24858 | 4,022.90 | .00196660 |
| 5 | 9.980 | 33,102.0 | .31346 | 3,190.20 | .00312730 |
| 6 | 12.58 | 26,250.0 | .39528 | 2,529.90 | .00497280 |
| 7 | 15.87 | 20,816.0 | .49845 | 2,006.20 | .00790780 |
| 8 | 20.01 | 16,509.0 | .62840 | 1,591.10 | .01257190 |
| 9 | 25.23 | 13,094.0 | .79242 | 1,262.00 | .01998530 |
| 10 | 31.82 | 10,381.0 | .99948 | 1,000.50 | .03178460 |
| 11 | 40.12 | 8,234.0 | 1.26020 | 793.56 | .05054130 |
| 12 | 50.59 | 6,529.9 | 1.58900 | 629.32 | .08036410 |
| 13 | 63.79 | 5,178.4 | 2.00370 | 499.06 | .12778800 |
| 14 | 80.44 | 4,106.8 | 2.52660 | 395.79 | .20318000 |
| 15 | 101.4 | 3,256.7 | 3.18600 | 313.87 | .32307900 |
| 16 | 127.9 | 2,582.9 | 4.01760 | 248.90 | .51373700 |
| 17 | 161.3 | 2,048.2 | 5.06600 | 197.39 | .81683900 |
| 18 | 203.4 | 1,624.3 | 6.38800 | 156.54 | 1.29876400 |