Type or paste a DOI name into the text box. The resource you are looking for has been removed, had its name changed, or electrical wiring residential 16th edition pdf temporarily unavailable. This article is about mains power connection devices used in domestic and light commercial environments. For other types, see Industrial and multiphase power plugs and sockets.
Plugs and sockets for portable appliances started becoming available in the 1880s, to replace connections to light sockets with easier to use wall-mounted outlets. A proliferation of types developed to address the issues of convenience and protection from electric shock. Today there are approximately 20 types in common use around the world, and many obsolete socket types are still found in older buildings. Plugs and sockets may sometimes combine male and female contacts, but the exposed pins or terminals in the socket are not energized. The International Electrotechnical Commission publishes IEC 60050, the International Electrotechnical Vocabulary, which is also available as IEV Online. Generally the plug is the movable connector attached to an electrically operated device’s mains cable, and the socket is fixed on equipment or a building structure and connected to an energised electrical circuit.
To reduce the risk of users accidentally touching energized conductors and thereby experiencing electric shock, plug and socket systems often incorporate safety features in addition to the recessed slots or holes of the energized socket. A socket may be surrounded by a decorative or protective cover called a wall plate, face plate, outlet cover, socket cover, or wall cover. In some designs this is an integral piece with the socket itself, bought and installed as a single unit. Electrical sockets for single phase domestic, commercial and light industrial purposes generally provide either two or three electrical connections to the supply conductors. IEC 60050 as a portable accessory constructed as an integral unit incorporating both a plug portion and one or more socket-outlet portions.
There is an alternative spelling, adapter, but adaptor is the form usually used in standards and official documents. When electricity was first introduced into houses, it was primarily used for lighting. At that time, many electricity companies operated a split-tariff system where the cost of electricity for lighting was lower than that for other purposes. As electricity became a common method of operating labour-saving appliances, a safe means of connection to the electric system other than using a light socket was needed. Thomas Tayler Smith of London, England received British patent 4162 in 1882 for an “Electric-Circuit Connection” to “enable the electric conductors conveying the current to one or more lamps, or along a flexible cord, to be rapidly and safely brought into connection with the line or main wires”.
Several early American electrical plug and socket arrangements were invented by Harvey Hubbell. On 26 February 1903 he filed two patent applications featuring 2-pin plugs and adaptors for using his plugs with existing designs of lamp sockets and wall receptacles. Hubbell’s catalogue of 1906 includes various three-way adaptors similar to those shown in the US 776,326 patent, but modified for use with the coplanar flat pin plugs. The Chapman receptacle must have been in general use at the time, as it was the only type of non-lampholder receptacle for which adaptors were supplied. A feature common to all of Hubbell’s patented designs is the provision of detents to retain a plug in its socket. This would have been a desirable feature in the days before wall receptacles became widespread and, for many consumers, the only source of electricity was an electric light socket. 1915 the use of Hubbell’s configuration was widespread.