Contested Currents
The Race to Electrify America

Resisting the Current
One of the greatest challenges to both Thomas Edison and George Westinghouse was the problem of electrical resistance and power loss in transmission lines. In the 1900's, there was simply no good way to transmit electrical power over long distances.

The power loss in a wire can be described by the formula P(loss) = I^2 x R, where power loss is the product the current squared, times the resistance of the wire. This means when the resistance is doubled, the power loss is twice as great. Since the resistance in a wire is directly proportional to distance traveled, a house twice as far from a power station would result in twice as much power lost. To transmit power to homes and businesses farther and farther away, something had to be done to decrease these power losses.

To reduce the resistance of the wires, Edison and Westinghouse could increase the size of the wires used. For example, they could have used a wire ten times as big for a house ten times as far away. Of course, this only would have worked over short distances, because wires can only be so big and still be produced and installed cheaply.

Another option was to increase the voltage used to transmit the electricity. Because the current (I) in a wire is equal to the power produced (P) divided by its voltage [I = P/V], you can rewrite the formula for power loss [P(loss) = I^2 x R] to be equal to the square of the power produced divided by its voltage, multiplied by the resistance of the wire [P(loss) = (P/V)^2 x R]. In this new equation, you can see that as the transmission voltage (V) increases, the power loss decreases by the square of the increase in voltage (I.e. if the voltage doubles, the power loss decreases by a quarter). It was therefore obvious that Edison and Westinghouse had to find a way to transmit large amounts of power at high voltages.

The key to high voltage electrical power distribution, was a power transformer developed by Lucien Gaulard and John Dixon Gibbs in 1881. The Gaulard-Gibbs transformer was one of the first that could handle large amounts of power and could be easily manufactured.