Electricity supply

Mains electricity is the general-purpose alternating-current (AC) electric power supply. Mains electricity is the form of electrical power that is delivered to homes and businesses, and it is the form of electrical power that consumers use when they plug kitchen appliances, televisions and electric lamps into wall sockets.

The two principal properties of the electric power supply, voltage and frequency, differ between regions. A voltage of (nominally) 230 V and a frequency of 50 Hz is used in Europe, most of Africa, most of Asia, most of South America and Australia. In North America, the most common combination is 120 V and a frequency of 60 Hz. Other voltages exist, and some countries may have, for example, 230 V but 60 Hz. This is a concern to travelers, since portable appliances designed for one voltage and frequency combination may not operate with or may be destroyed by another. The use of different and incompatible plugs and sockets in different regions and countries provides some protection from accidental use of appliances with incompatible voltage and frequency requirements.

In the US, mains electric power is referred to by several names including "household power", "household electricity", "house current", "powerline", "domestic power", "wall power", "line power", "AC power", "city power", "street power", and "the grid".

In the UK, mains electric power is generally referred to as "the mains".

For a list of voltages, frequencies, and wall plugs by country, see Mains electricity by country

Worldwide, many different mains power systems are found for the operation of household and light commercial electrical appliances and lighting. The different systems are primarily characterized by their

All these parameters vary among regions. The voltages are generally in the range 100–240 V (always expressed as root-mean-square voltage). The two commonly used frequencies are 50 Hz and 60 Hz. Single-phase or three-phase power is most commonly used today, although two-phase systems were used early in the 20th century. Foreign enclaves, such as large industrial plants or overseas military bases, may have a different standard voltage or frequency from the surrounding areas. Some city areas may use standards different from that of the surrounding countryside (e.g. in Libya). Regions in an effective state of anarchy may have no central electrical authority, with electric power provided by incompatible private sources.

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