Editing Mains electricity (section)

== Building wiring ==
{{See also|Electrical wiring}}

Portable appliances use single-phase electric power, with two or three wired contacts at each outlet. Two wires (neutral and live/active/hot) carry current to operate the device.<ref>[https://books.google.com/books?id=83v7hptwljkC&dq=live+parts+energized+conductive+components&pg=PA29]''Electrical Inspection Manual, 2011 Edition''], Noel Williams & Jeffrey S Sargent, Jones & Bartlett Publishers, 2012, p. 249 (retrieved 3 March 2013 from Google Books)</ref><ref>[https://books.google.com/books?id=4kugySmaTeAC&dq=%22live+part%22&pg=PA44]''17th Edition IEE Wiring Regulations: Explained and Illustrated''], Brian Scaddan, Routledge, 2011, p. 18 (retrieved 6 March 2013 from Google Books)</ref> A third wire, not always present, connects conductive parts of the appliance case to earth ground. This protects users from electric shock if live internal parts accidentally contact the case.

{{further|Ground and neutral}}

In northern and central Europe, residential electrical supply is commonly 400&nbsp;V three-phase electric power, which gives 230&nbsp;V between any single phase and neutral; house wiring may be a mix of three-phase and single-phase circuits, but three-phase residential use is rare in the UK. High-power appliances such as [[kitchen stove]]s, water heaters and household power heavy tools like [[log splitter]]s may be supplied from the 400&nbsp;V three-phase power supply.

Small portable electrical equipment is connected to the power supply through flexible cables terminated in a plug, which is inserted into a fixed receptacle (socket). Larger household electrical equipment and industrial equipment may be permanently wired to the fixed wiring of the building. For example, in North American homes a window-mounted self-contained [[Air conditioning|air conditioner]] unit would be connected to a wall plug, whereas the central air conditioning for a whole home would be permanently wired. Larger [[Industrial and multiphase power plugs and sockets|plug and socket combinations]] are used for industrial equipment carrying larger currents, higher voltages, or three phase electric power.

[[Circuit breaker]]s and [[fuse (electrical)|fuse]]s are used to detect [[short circuit]]s between the line and neutral or ground wires or the drawing of more current than the wires are rated to handle (overload protection) to prevent overheating and possible fire. These protective devices are usually mounted in a central panel—most commonly a distribution board or consumer unit—in a building, but some wiring systems also provide a protection device at the socket or within the plug. [[Residual-current device]]s, also known as ground-fault circuit interrupters and appliance leakage current interrupters, are used to detect ''ground faults''—flow of current in other than the neutral and line wires (like the ground wire or a person). When a ground fault is detected, the device quickly cuts off the circuit.