Household appliances may be labeled for use with 120, 115 or even 110 volt outlets. Regardless of the number, actual voltage at the outlet varies; however, for all practical purposes, these outlets can be treated as if they are the same.
In North America household electrical current is wired for one of two voltages, specified as 120 volt and 240 volt. The 120 volt circuits come from splitting a 240 volt circuit into two "legs."
The actual current supplied is required to fall in a range of plus or minus 5 percent, which equals 114 to 126 volts for 120 volt circuits, although the actual range is closer to 117 to 124 volts. Due to resistance in household wiring, the actual voltage at an outlet may be even lower, commonly as low as 110 volts.
Practically speaking, 110, 115 or 120 volts can be used interchangeably for appliances and electrical outlets. In fact, some appliances are actually designed to work best with 110 volts because this voltage is often found in outlets labeled 120 or 115 volt.