Mains electricity by country includes a list of countries and territories, with the plugs, voltages and frequencies they commonly use for providing electrical power to low voltage appliances, equipment, and lighting typically found in homes and offices. (For industrial machinery, see industrial and multiphase power plugs and sockets.) Some countries have more than one voltage available. For example, in North America, a unique split-phase system is used to supply to most premises that works by center tapping a 240 volt transformer. This system is able to concurrently provide 240 volts and 120 volts. Consequently, this allows homeowners to wire up both 240 V and 120 V circuits as they wish (as regulated by local building codes). Most sockets are connected to 120 V for the use of small appliances and electronic devices, while larger appliances such as dryers, electric ovens, ranges and EV chargers use dedicated 240 V sockets. Different sockets are mandated for different voltage or maximum current levels.
Voltage, frequency, and plug type vary, but large regions may use common standards. Physical compatibility of receptacles may not ensure compatibility of voltage, frequency, or connection to earth (ground), including plugs and cords. In some areas, older standards may still exist. Foreign enclaves, extraterritorial government installations, or buildings frequented by tourists may support plugs not otherwise used in a country, for the convenience of travellers.