AC power plugs and sockets

A socket (also known as a receptacle or outlet) is fixed in place, often on the internal walls of buildings, and is connected to an AC electrical circuit.

Coordination of technical standards has allowed some types of plug to be used across large regions to facilitate the production and import of electrical appliances and for the convenience of travellers.

Other portable appliances (such as vacuum cleaners, electric fans, smoothing irons, and curling-tong heaters) were connected to light-bulb sockets.

[citation needed] Designs of plugs and sockets have gradually developed to reduce the risk of electric shock and fire.

Contact pins may be sheathed with insulation over part of their length, so as to reduce exposure of energized metal during insertion or removal of the plug.

Where a "neutral" conductor exists in supply wiring, polarisation of the plug can improve safety by preserving the distinction in the equipment.

For example, appliances may ensure that switches interrupt the line side of the circuit, or can connect the shell of a screw-base lampholder to neutral to reduce electric shock hazard.

This allows connecting more than one electrical consumer item to one single socket and is mainly used for low power devices (TV sets, table lamps, computers, etc.).

In some countries these adaptors are banned and are not available in shops, as they may lead to fires due to overloading them or can cause excessive mechanical stress to wall-mounted sockets.

[3][4] Safety advocates, the United States Army,[5] and a manufacturer of sockets[6] point out a number of safety issues with universal socket and adaptors, including voltage mismatch, exposure of live pins, lack of proper earth ground connection, or lack of protection from overload or short circuit.

In Brazil, similar plugs and sockets are still commonly used in old installations for high-power appliances like air conditioners, dishwashers, and household ovens.

Since Brazil adopted the NBR 14136 standard which includes a 20 A version, the original motivation to use the NEMA 10-20 plug has ceased to exist.

Australian and New Zealand wall sockets (locally often referred to as power points) almost always have switches on them for extra safety, as in the UK.

Some of these countries have national standards based on BS 1363, including: Bahrain, Hong Kong,[14] Ireland, Cyprus, Malaysia, Malta, Saudi Arabia, Singapore, Sri Lanka, and UAE.

The International Commission on the Rules for the Approval of Electrical Equipment (IECEE) was a standards body which published Specification for plugs and socket-outlets for domestic and similar purposes as CEE Publication 7 in 1951.

The socket has a circular recess with two round holes and two earthing clips that engage before live pin contact is made.

[citation needed] The few European countries not using it at all are Belgium, Czech Republic, Cyprus, Ireland, Liechtenstein, Switzerland, and the UK, or not using it predominantly are Denmark, Faroe Island, France, Italy, Monaco, San Marino, Slovakia.

Alternative II, popularly known as the Europlug, is a flat 2.5 A-rated plug defined by Cenelec standard EN 50075 and national equivalents.

This transition aims to improve electrical safety and standardization, aligning South Africa with international plug and socket systems.

Few private houses in Brazil have an earthed supply, so even if a three-pin socket is present it is not safe to assume that all three terminals are actually connected.

Europlugs are also in common use in Italy; they are standardized under CEI 23-34 S 1 for use with the 10 A socket and can be found fitted to Class II appliances with low current requirement (less than 2.5 A).

The devices are named using the format NEMA n-mmX, where n is an identifier for the configuration of pins and blades, mm is the maximum current rating, and X is either P for plug or R for receptacle.

Within the series, the arrangement and size of pins will differ, to prevent accidental mating of devices with a higher current draw than the receptacle can support.

[48] In stage lighting, this connector is sometimes known as PBG for Parallel Blade with Ground, Edison or Hubbell, the name of a common manufacturer.

NEMA 14-50 devices are frequently found in RV parks, since they are used for "shore power" connections of larger recreational vehicles.

Newer applications include Tesla's Mobile Connector for vehicle charging, which formally recommended the installation of a 14-50 receptacle for home use.

They were also used in the Ministry of Defence Main Building inside circuits powered from the standby generators to stop staff from plugging in unauthorised devices.

[71] The socket is rectangular, with lateral key pins and indentations to maintain polarisation, and to prevent insertion of a plug with different current ratings.

Even so, the Magic security system had some success at first because its enhanced safety features appealed to customers; standard connectors of the day were not considered safe enough.

This allows delicate electronics equipment to be connected to an independent circuit breaker, usually including a surge protector or an uninterruptible power supply backup.