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Plugs and sockets for portable appliances originated in Britain in the 1880s and were initially two pin designs. These were usually sold as a mating pair, but gradually de facto and then official standards arose to enable the interchange of compatible devices. British standards have proliferated throughout large parts of the former British Empire. BS 546, ''Two-pole and earthing-pin plugs, socket-outlets and socket-outlet adaptors for AC (50-60 Hz) circuits up to 250 V'' is a British Standard for three pin AC power plugs and sockets. Originally published in April 1934, it was updated by a 1950 edition which is still current,〔BS 546: "Specification. Two-pole and earthing-pin plugs, socket-outlets and socket-outlet adaptors" (1950)〕 with eight amendments up to 1999. BS 546 is also the precursor of current Indian and South African plug standards. The 5 A version has been designated as ''Type D'' and the 15 A as ''Type M''. BS 546 plugs and sockets are still permitted in the UK, provided the socket has shutters. BS 1363, ''13 A plugs socket-outlets adaptors and connection units'' is a British Standard which specifies the most common type of single-phase AC power plugs and sockets that are used in the United Kingdom. Distinctive characteristics of the system are shutters on the neutral and (see Concepts and Terminology below) socket holes, and a fuse in the plug. It has been adopted in many former British overseas territories. BS 1363 was introduced in 1947 as one of the new standards for electrical wiring in the United Kingdom used for post-war reconstruction. The plug and socket replaced the BS 546 plug and socket, which are still found in old installations or in special applications. BS 1363 plugs have been designated as ''Type G'' ==Concepts and terminology== 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. The plug has protruding pins (referred to as ''male'') that fit into matching apertures (called ''female'') in the sockets. Sockets are designed to prevent exposure of bare energised contacts. 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 contacts of the energized socket. These include plugs with insulated sleeves, sockets with blocking shutters, and sockets designed to accept only compatible plugs inserted in the correct orientation. The term ''plug'' is in general and technical use in all forms of English, common alternatives being ''power plug'',〔(), Assembly Automation and Product Design, Second Edition, Geoffrey Boothroyd, CRC Press, 2005, p.315 (retrieved 20 December 2013 from Google Books)〕 ''electric plug'',〔(), Physics for AQA, Patrick Fullick, Heinemann, 2001, p.16 (retrieved 1 March 2013 from Google Books)〕 and ''plug top''.〔(), Trevor Linsley, Routledge, 2008, p.37 (retrieved 2 March 2013 from Google Books)〕 The normal technical term for an AC power socket is ''socket-outlet'',〔(), IEC/TR 60083 Ed. 6.0, IEC, 2009 (retrieved 1 March 2013 from Techstreet)〕 but in non-technical common use a number of other terms are used. The general term is ''socket,'' but there are numerous common alternatives, including ''power point'', ''plug socket'',〔(), Building Surveys and Reports, James Douglas, John Wiley & Sons, 2010, p.254 (retrieved 1 March 2013 from Google Books)〕 ''wall socket'',〔(), Computer Networking First-Step, Wendell Odom, Cisco Press, 2004, p.38 (retrieved 1 March 2013 from Google Books)〕 and ''wall plug''.〔(), Building Technology: Mechanical and Electrical Systems, Benjamin Stein, John Wiley & Sons, 1997, p.723 (retrieved 1 March 2013 from Google Books)〕 Modern British sockets for domestic use are normally manufactured as single or double units with an integral face plate and are designed to fit standard mounting boxes. Electrical sockets for single phase domestic, commercial and light industrial purposes generally provide three electrical connections to the supply conductors. These are termed ''neutral'', ''line'' and ''earth''. Both neutral and line carry current and are defined as ''live parts''.〔()''17th Edition IEE Wiring Regulations: Explained and Illustrated''], Brian Scaddan, Routledge, 2011, p.18 (retrieved 6 March 2013 from Google Books)〕 Neutral is usually at or very near to earth potential, being earthed either at the substation or at the service entrance (neutral-to-earth bonding is not permitted in the distribution board/consumer unit). Line (commonly, but technically incorrectly, called ''live'') carries the full supply voltage relative to the neutral. The ''protective earth''〔()''Electrical Product Safety''], Dave Holland, M.B, Jimmy Tzimenakis, Newnes, 1999, p.58 (retrieved 3 March 2013 from Google Books)〕 connection allows the exposed metal parts of the appliance to be connected to earth, providing protection to the user should those exposed parts inadvertently come into contact with any live parts within the appliance. Historically, two-pin sockets without earth were used in Britain, but their use is now restricted to sockets specifically designated for shavers and toothbrushes. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「AC power plugs and sockets: British and related types」の詳細全文を読む スポンサード リンク
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