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Frequency and voltage supplied to most premises by country. 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.
Another requirement is to provide low-voltage electricity to a device from mains electricity; this would be done by what is usually called a power supply.Most modern electronic devices require between 1.5 and 24 volts DC; lower-powered devices at these voltages can often work either from batteries or mains.
Mains electricity or utility power, grid power, domestic power, and wall power, or, in some parts of Canada, hydro, is a general-purpose alternating-current (AC) electric power supply.
Fig. 1 Fig. 2. A transformer supplying a three-wire distribution system has a single-phase input (primary) winding. The output (secondary) winding has a center tap connected to a grounded neutral.
This map reflects the nominal voltage of residential buildings of most countries. In the USA and Canada, there are 2 nominal voltages: 120V and 240V concurrently. This is not a 3 phase system and 240V is not a phase-phase voltage. This system is unique and is only used in certain parts of the world. 230/380V in Europe does not use a similar system.
In 1903, Harvey Hubbell filled the U.S. patent 774,250, for a lightbulb socket adaptor and plug, also a standalone receptacle.The adaptor was screwed into the lightbulb socket, leaving a flat face with two holes to conveniently attach the plug.
Power supplies are categorized in various ways, including by functional features. For example, a regulated power supply is one that maintains constant output voltage or current despite variations in load current or input voltage.
Single phase power transmission took many years to develop. The earliest developments were based on the early alternator inventions of 19th century Parisian scientist Hippolyte Pixii, which were later expanded upon by Lord Kelvin and others in the 1880s.