The standard voltage of a home electrical outlet in the United States is 120 volts, although the actual voltage supplied may be as low as 110 volts, due to line conditions. A few appliances, like stoves and electric dryers, may use 240 volts, which require special wiring and outlets.
The actual voltage supplied to a home from the electric utility is 240 volts, split across two "legs." Most outlets are wired to one leg and a neutral leg. This provides half the total incoming voltage, or 120 volts. 240-volt outlets are wired to both of the incoming legs, providing the full voltage.