Plants, Poles and Plugs
Electricity Is Measured In Watts.
Electricity is measured in units of power called watts. One watt is such a small amount of power, however, that the more commonly used measurement is the kilowatt, representing 1,000 watts. The higher the watt or kilowatt rating of a particular electrical device, the more electricity it requires.
The amount of electricity a power plant generates or a customer uses over a period of time is measured in kilowatt-hours (kWh). Kilowatt-hours are determined by multiplying the number of watts required by the number of hours of use, and then dividing by 1,000. For example, if you use a 60-watt light bulb five hours a day for 30 days, you have used 60 watts of power for 150 hours, or nine kWh of electrical energy. Although electricity use varies widely depending on the season and the region of the country, a typical household uses about 938 kWh of electricity a month.
 U.S. Department of Energy, Energy Information Administration, Electric Power Annual 2005, October 2006.