   #copyright

Domestic AC power plugs and sockets

2007 Schools Wikipedia Selection. Related subjects: Engineering

   CEE 7/7 plug and socket
   Enlarge
   CEE 7/7 plug and socket

          This article covers only plugs and sockets intended for common
          domestic use. For plugs and sockets used for industrial
          applications, or with more than two current carrying conductors,
          see Industrial & multiphase power plugs & sockets. For less
          common plugs and sockets see unusual and obsolete plugs and
          sockets.

   Domestic AC power plugs and sockets are devices that connect the home
   appliances and portable light fixtures commonly used in homes to the
   commercial power supply so that AC electric power can flow to them.

   Power plugs are male electrical connectors that fit into female
   electrical sockets. They have contacts that are pins or blades which
   connect mechanically and electrically to holes or slots in the socket.
   Plugs usually have a live or hot contact, a neutral contact, and an
   optional earth or ground contact. Many plugs make no distinction
   between the live and neutral contacts, and in some cases they have two
   live contacts. The contacts may be brass, tin or nickel plated.

   Power sockets are female electrical connectors that have slots or holes
   which accept the pins or blades of power plugs inserted into them and
   deliver electricity to the plugs. Sockets are usually designed to
   reject any plug which is not built to the same electrical standard.
   Some sockets have one or more pins that connect to holes in the plug.

   Standard wire colours for flexible cable
   Region Live Neutral Protective earth
   EU, Australia & South Africa ( IEC 60446) brown blue green & yellow
   UK, Ireland & Australia before  1969 red black green
   United States and Canada (screw colour) black (brass) white (silver)
   green (green)
   Standard wire colours for fixed cable
   Region Live Neutral Protective earth
   EU ( IEC 60446) including UK from 31 March 2004 brown or black blue
   green & yellow
   UK before 1 April 2006 & Australia red black green & yellow (core is
   usually bare and should be sleeved at terminations)
   United States and Canada (screw colour) black or red (brass) white
   (silver) green or bare (green)
   Note: the colours in this table represent the most common and preferred
   standard colours however others may be in use, especially in older
   installations.

The three contacts

   In most countries, household power is single-phase electric power, in
   which a single live conductor brings alternating current into a house,
   and a neutral returns it to the power supply. Many plugs and sockets
   include a third contact used for a protective earth ground, which only
   carries current in case of a fault in the connected equipment.

Live or Phase

   The live contact (also known as phase, hot or active) carries
   alternating current from the power source to the equipment. The voltage
   varies by country, as set by national standards. In some installations,
   there may be two live conductors, either being two phases from a
   three-phase system or being both phases from a split phase system. Some
   plug/socket combinations are designed in a way that a plug can be
   inserted only one possible way — this is referred to as a polarized
   plug (not to be confused with positive and negative polarity). Others
   allow the plug to be inserted with live and neutral either way round —
   this is referred to as an unpolarized plug. Furthermore even if live
   and neutral can only connect one way, in some countries it is common to
   wire them without regard for which is which. This can be hazardous with
   some equipment in which the neutral is connected directly to the
   chassis.

Neutral

   The neutral contact returns current from the equipment back to the
   power source or distribution panel. It is in most (but not all) cases
   referenced to the earth. Except under fault conditions it does not pose
   a danger because the voltage between the neutral contact and the earth
   is close to zero, but is nevertheless treated as live in most
   installation practices because it can develop a high voltage under
   fault conditions.

   The main danger posed by the neutral is the voltage can rise as high as
   the voltage on the live conductor if a broken neutral cable in the
   wiring disconnects the neutral but leaves the live conductor connected.
   Another possibility is that the live and neutral may be reversed or
   crossed by improper installation.

   Neutral and earth (ground) are closely related and are usually
   connected at some point. However extra connections between the neutral
   and the earth should be avoided unless the relevant jurisdiction's
   regulations allow it. Connecting neutral and earth at more than one
   point can sometimes create a dangerous ground loop in the system.

Earth/Ground

   The earth contact (known as ground in American English) is only
   intended to carry electric current when connected to equipment that has
   developed an insulation fault (except for EMI/RFI filters which do
   cause a small current down the earth). The earth connection was added
   to modern plugs because, if a live wire or other component in a device
   touches the metal casing, anybody touching the device may receive a
   dangerous electric shock. In many countries devices with metal cases
   must have the case connected to the earth contact. This reduces but
   does not eliminate the possibility of the case developing a high
   voltage relative to the earth and grounded metalwork.
   A grounding adapter, which allows devices with a ground pin to be
   attached to an ungrounded receptacle (United States). These devices are
   illegal in most jurisdictions.
   Enlarge
   A grounding adapter, which allows devices with a ground pin to be
   attached to an ungrounded receptacle (United States). These devices are
   illegal in most jurisdictions.

   It is a common misconception that the purpose of the earth connection
   is to take fault currents safely to earth. The primary purpose of the
   earthing system is to cause a fuse to blow or a breaker or a
   residual-current device (RCD) to trip to automatically disconnect the
   power supply to any device or cable which develops a wiring fault. The
   secondary purpose is to hold all touchable metal in a house to the same
   voltage to prevent electrical shocks when touching two metal objects at
   the same time.

   There are two main approaches to the problem of how to disconnect power
   when a live wire comes into contact with metalwork attached to the
   earthing system. One way is to get the resistance through the fault
   path and back to the supply very low by having a metallic connection
   from the earth back to the supply transformer (a TN system). Then when
   a fault happens a very high current will flow rapidly blowing a fuse
   (or tripping a MCB).

   Where such a direct connection is not used (a TT system) the resistance
   of the fault path back to the supply is almost invariably far higher
   and as a result the fault current is generally too low to reliably blow
   fuses (or trip MCBs). Therefore an RCD must normally be used to
   disconnect the fault.

   The neutral core could in theory be used as a ground, but this would be
   dangerous if the core broke, so this is not normally used in building
   wiring or portable appliances. It is, however, used in some other
   situations with special precautions. For instance, in Switzerland,
   sockets in houses with the old two wire installation have the ground
   and neutral contacts connected together, probably supposing, that the
   professionally maintained house installation is much more reliable than
   plugged-in device. Also using the neutral as a ground prevents the use
   of RCDs.

Differences in terminology

   There are significant differences between American English and British
   English in talking about power plugs and sockets.
   British American Meaning
   mains power line power House electrical AC current
   earth connection ground connection Safety connection to the earth or
   ground
   flex cord Flexible electric cable from plug to appliance
   socket, power point outlet, receptacle Female part of an electrical
   connection
   pin prong Male part of an electrical connector

   In the United States, the live contact may be called live or hot. The
   neutral contact may be called cold, neutral, the grounded conductor, or
   (in the National Electrical Code), the identified conductor. The earth
   contact is called ground or the grounding conductor.

   In the United Kingdom the word "line" is occasionally used to denote
   the live terminal or wire. This terminology derives from its being at
   the line voltage relative to neutral and ground, as distinct from the
   "phase" voltage, between lines on different phases of the supply.

   Live conductors are called phases when there is more than a single
   phase in use. Pins are also known as prongs, contacts or terminals.

   In Australia, the live contact is called active.

History of plugs and sockets

   Light fitting plug with toaster
   Enlarge
   Light fitting plug with toaster

   When electricity was first introduced into the household, 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. This led to low-power
   appliances (such as vacuum cleaners and hair driers) being connected to
   the light fitting. The picture to the right shows a 1909 electric
   toaster with a light bulb socket plug.
   U.S. Patent 774,250. The first electric power plug and receptacle.
   Enlarge
   U.S. Patent 774,250. The first electric power plug and receptacle.

   However, as electricity became a common method of heating houses and
   operating labour-saving appliances, a means of connection to the
   electric system other than using a light socket was needed. The
   original two prong electrical plug and socket were invented by Harvey
   Hubbell and patented in 1904.

   The three prong plug was invented in 1928 by Philip F. Labre, while he
   was going to school at the Milwaukee School of Engineering (MSOE). It
   is said that his landlady had a cat which would knock over her fan when
   it came in the window. When she plugged the fan back in, she would get
   an electric shock. Philip figured out that if the plug was grounded,
   the electricity would go to earth through the plug rather than his
   landlady. He applied for and was issued a patent for grounding
   receptacle and plug on June 5, 1928. As the need for safer
   installations became apparent, earthed three-contact systems were made
   mandatory in most industrial countries.

Proliferation of standards

   The reason that there are now over a dozen different styles of plugs
   and wall outlets is that when European countries adopted 220-240V
   electricity, for nationalistic reasons they developed their own unique
   national plug designs instead of agreeing on a European standard plug.
   In contrast, the 38 different countries which adopted the American
   110-120V standard electricity also adopted the U.S. type A and B plugs.
   Most countries elsewhere in the world were once colonies of European
   nations and usually adopted the standards of their colonial governments
   at the time electricity was introduced. In many other countries there
   is no single national standard and multiple voltages, frequencies and
   plug designs are in use, creating extra complexity and potential safety
   problems for users.

   However, in recent years most countries have settled on one of a few de
   facto standards, although there are legacy installations of obsolete
   wiring in most countries of the world. Some buildings have wiring that
   has been in use for almost a century and which pre-dates all modern
   standards.
   IEC power cord with CEE 7/7 plug at left end.
   Enlarge
   IEC power cord with CEE 7/7 plug at left end.

   To minimize the difficulty of designing for different national
   standards, many manufacturers of electrical devices like personal
   computers have adopted the practice of putting a single world-standard
   IEC connector on the device, and supplying for each country a power
   cord equipped with a standard IEC connector on one end and a national
   power plug at the other. The device itself is designed to adapt to a
   wide range of voltage and frequency standards.

World maps by plug/socket and voltage/frequency

   There are two basic standards for voltage and frequency in the world.
   One is the North American standard of 110-120 volts at 60 Hz, which
   uses plugs A and B, and the other is the European standard of 220-240
   volts at 50 Hz, which uses plugs C through M. The differences arose for
   historical reasons.

   In the United States, Thomas Edison, the inventor of the first
   practical electric light bulb, insisted on using 110 volts direct
   current (DC) rather than alternating current (AC) for his electric
   system in New York City. However, George Westinghouse, who built the
   first large hydro-electric plants at Niagara Falls, decided to use AC
   instead of DC because it could be stepped up or stepped down in voltage
   using transformers. The electrical genius Nicola Tesla advised him that
   240 V at 60 Hz was optimum, but authorities would not let him use more
   than 110 V for distribution. Eventually Edison switched his 110 V DC
   system over to AC as well, and so 110 V at 60 Hz became the American
   electrical standard, despite the fact it required conductors twice as
   large to carry the same amount of power as 240 V.

   In Europe, the German company AEG built the first generating
   facilities, and chose 50 Hz because it fit better into the metric
   system of powers of ten (1, 10, 100). Unfortunately, 50 Hz is less
   efficient than 60 Hz because generators are 20% less efficient and
   transformers must be 30% bigger to step the voltage up and down.
   However, AEG had a virtual monopoly in Europe so their standard spread
   to the rest of the continent and eventually to Britain. Originally
   Europe was electrified at 110-120 V like North America, but after World
   War II, regulators decided to increase it to 220-240 V to reduce the
   amount of copper used for wiring.

   American regulators would have liked to double the voltage as well, but
   there were far more household electrical appliances than in Europe.
   They compromised by adopting a split phase 240 V system, supplying 120
   V on two live conductors going into each household with a single
   neutral. Small appliances ran on 120 V, big ones on 240 V. It was more
   complicated but saved copper and was backward-compatible with existing
   appliances. The original plugs could be used with the system, as well.

   Countries on other continents have adopted one of these two voltage
   standards, although some countries use variations or a mixture of
   standards. The outline maps below show the different plug types,
   voltages and frequencies used around the world, colour-coded for easy
   reference.

   See also List of countries with mains power plugs, voltages and
   frequencies for specific places.
   Voltage/Frequency. Click for larger version.
   Enlarge
   Voltage/Frequency. Click for larger version.
   Plugs. Click for larger version.
   Enlarge
   Plugs. Click for larger version.

Types of plug and sockets

   Electrical plugs and their sockets differ by country in shape, size,
   and type of connectors. The type used in each country is set by
   national standards legislation. In this article each type is designated
   by a letter, plus a short comment in parentheses giving its country of
   origin and number of contacts. Subsections then detail the subtypes of
   each type as used in different parts of the world.

   Note that IEC Class I refers to earthed equipment. IEC Class II refers
   to unearthed equipment protected by double insulation. See Appliance
   classes.

Type A (North American/Japanese 2-pin)

   NEMA 1-15 (North American 15 A/125 V ungrounded)

   Standardized by the U.S. National Electrical Manufacturers Association
   and adopted by 38 other countries, this simple plug with two flat
   parallel pins, or blades, is used in most of North America and on the
   west coast of South America on devices not requiring a ground
   connection, such as lamps and "double-insulated" small appliances. NEMA
   1-15 sockets have been prohibited in new construction in the United
   States and Canada since 1965, but remain in many older homes and are
   still sold "for replacement use only". Type A plugs are still very
   common because they are compatible with type B sockets.

   Early designs could be inserted either way, but modern ones prevent the
   neutral pin from being inserted into the live socket by making it wider
   than the live one, referred to as a polarized plug. (Note that this is
   not the same as positive/negative polarization in a direct current
   system.) New polarized plugs will not fit in old type A sockets, but
   both old and new type A plugs will fit in new type A and type B
   sockets. Some devices that do not distinguish between neutral and live,
   such as sealed electronic power supplies, are still sold with both pins
   narrow. When attaching a new polarized plug to a cord, it is useful to
   remember that the most common type of two-conductor cord for low-power
   use in North America has smooth insulation on the "hot" side and ribbed
   insulation on the "neutral" side.

   JIS 8303, Class II (Japanese 15 A/100 V ungrounded)

   The Japanese plug and socket are identical to NEMA 1-15. However, the
   Japanese system incorporates stricter dimensional requirements for the
   plug housing, different marking requirements, and mandatory testing and
   approval by MITI or JIS.

   Some Japanese outlets are non-polarized — the slots in the sockets are
   the same size - and will only accept non-polarized plugs. Japanese
   plugs should be able to fit into North American outlets without
   trouble, but North American appliances with polarized plugs may require
   adapters or replacement non-polarized plugs to connect to Japanese
   outlets.

   Japanese standard wire sizes and the resulting current ratings are
   somewhat different from those used elsewhere in the world. Japanese
   voltage is only 100 volts - lower than American voltage - and the
   frequency in eastern Japan is only 50 hertz instead of 60, so even if a
   North American plug can be inserted into a Japanese socket, it does not
   always mean the device will work properly.

Type B (American 3-pin)

   An American grounded (earthed) plug. Note that the receptacle will also
   accept an ungrounded (two prong) plug whether polarized or unpolarized.
   Enlarge
   An American grounded (earthed) plug. Note that the receptacle will also
   accept an ungrounded (two prong) plug whether polarized or unpolarized.

   NEMA 5-15 (North American 15 A/125 V grounded)

   The type B plug has two flat parallel blades like type A, but has a
   round ground or earthing pin (American standard NEMA 5-15/Canadian
   standard CSA 22.2, Nº42). It is rated for 15 amps at 125 volts. The
   ground pin is longer than the live and neutral blades, so the device is
   grounded before the power is connected. The neutral blade in the type B
   socket is wider than the live one to prevent type A plugs being
   inserted upside-down, but type B plugs often have both pins narrow
   since the ground pin enforces polarity.

   The 5-15 socket is standard in all of North America (Canada, the United
   States and Mexico). It is also used in Central America, the Caribbean,
   the west coast of South America, Japan, parts of Korea, and Taiwan.
   Pin orientation on the type B (NEMA 5-15) socket
   Pin orientation on the type B (NEMA 5-15) socket

   With type B plugs, if you look directly at a socket with the ground
   socket at a bottom, the neutral slot is on the left, and the live slot
   is on the right. They may also be installed with the ground at the top
   or on either side, but the sockets going clockwise are always ground,
   neutral, live. The plug has the same connections going
   counterclockwise. If the plug is polarized, the widest pin is the
   neutral connector.

   Due to the low power (1.8KW) available from a 120V 15A socket a number
   of other NEMA connector for higher currents and 240 V supplies are also
   commonly encountered in North American homes.

   JIS 8303, Class I (Japanese 15 A/100 V grounded)

   Japan also uses a Type B plug similar to the North American one.
   However it is less common than its Type A equivalent.

Type C (European 2-pin)

   CEE 7/16 (Europlug 2.5 A/250 V unearthed)

   CEE 7/16 plug and socket
   Enlarge
   CEE 7/16 plug and socket

   This two-pin plug is probably the single most widely used international
   plug, popularly known as the Europlug. The plug is unearthed and has
   two round, 4 mm pins, which usually converge slightly. It can be
   inserted into any socket that accepts 4 mm round contacts spaced 19 mm
   apart. It is described in CEE 7/16. and is also defined in Italian
   standard CEI 23-5 and Russian standard GOST 7396

   The Europlug is used in Class II applications throughout continental
   Europe (Germany, Austria, Switzerland, Italy, Greece, the Netherlands,
   Belgium, France, Spain, Portugal, Denmark, Norway, Sweden, Finland,
   Poland, The Czech Republic, Slovakia, Hungary, Romania, Bulgaria). It
   is also used in Turkey, the Middle East, most of Africa and South
   America (Brazil), as well as the former Soviet republics, and many
   developing nations.

   This plug is intended for use with devices that require 2.5 A or less.
   Because it can be inserted in either direction into the socket, live
   and neutral are connected at random.
   CEE 7/17 plug
   Enlarge
   CEE 7/17 plug

   CEE 7/17 (German/French 16 A/250 V unearthed)

   This plug also has two round pins but the pins are 4.8 mm in diameter
   like types E and F and the plug has a round plastic or rubber base that
   stops it being inserted into small sockets intended for the Europlug.
   Instead, it fits only into large round sockets intended for types E and
   F. The base has holes in it to accommodate both side contacts and
   socket earth pins. It is used for large Class II appliances. Often used
   in South Korea, it is also defined in Italian standard CEI 23-5.
   BS 4573 socket
   Enlarge
   BS 4573 socket

   BS 4573 (UK shaver)

   In the United Kingdom and Ireland, there is a special version of the
   type C plug for use with shavers (electric razors) in bath or shower
   rooms. It has 5 mm diameter pins 16.6 mm apart, and the sockets for
   this plug can often take CEE 7/16, US and/or Australian plugs as well.
   Sockets are often able to supply either 230 V or 115 V. In wet zones,
   they must contain an isolation transformer compliant with BS 3535.
   Unearthed socket compatible with both Schuko and French plugs
   Enlarge
   Unearthed socket compatible with both Schuko and French plugs

   Variations in sockets

   Some Type C sockets can only take 4 mm pins or have plastic barriers in
   place to prevent Schuko or French plugs from entering. However, many
   can take 4.8 mm pins and have enough room for a 4.8 mm pin round Schuko
   or French plug to be inserted.

Type D (Old British 3-pin)

   BS 546 (Indian 5 A/250 V earthed)

   D

   India has standardised on a plug which was originally defined in
   British standard BS 546. It has three large round pins in a triangular
   pattern. The BS 546 standard is also used in parts of Africa (Ghana,
   Kenya, Nigeria), the Middle East (Kuwait, Qatar), and parts of Asia and
   the Far East that were electrified by the British. This type was also
   previously used in South Africa, but has been phased out in favour of
   the 15 A version there. This 5 A plug, along with its 2 A cousin, is
   sometimes used in the UK for centrally switched domestic lighting
   circuits, in order to distinguish them from normal power circuits.

   BS 546 (South African 15 A/250 V earthed)

   M

   This plug is sometimes referred to as type M, but it is in fact merely
   the 15 A version of the plug above, though its pins are much larger at
   7.05 mm × 21.1 mm. Live and neutral are spaced 25.4 mm apart, and earth
   is 28.6 mm away from each of them. Although the 5 A version is standard
   in India, Sri Lanka, Nepal, and Namibia, the 15 A version is also used
   in these countries for larger appliances. Some countries like South
   Africa use it as the main domestic plug and socket type, where sockets
   almost always have an on–off switch built into them. The Type M is
   almost universally used in the UK for indoor dimmable theatre and
   architectural lighting installations. It is also often used for
   non-dimmed but centrally controlled sockets within such installations.
   The main reason for doing this is that fused plugs, while convenient
   for domestic wiring (as they allow 32 A socket circuits to be used
   safely), are not convenient if the plugs and sockets are in hard to
   access locations (like lighting bars) or if using chains of extension
   leads (since it is hard to figure out which fuse has blown). Both of
   these situations are common in theatre wiring. This plug is also widely
   used in Israel for air conditioners.

Type E (French 2-pin, female earth)

                                                             French socket

                                                               French plug

   French type E

   France, Belgium, Poland, Czech Republic, Slovakia and some other
   countries have standardised on a socket which is not compatible with
   the CEE 7/4 socket (type F) that is standard in Germany and other
   continental European countries. The reason for incompatibility is that
   earthing in the E socket is accomplished with a round male pin
   permanently mounted in the socket. Sockets are installed with the earth
   pin upwards and wired with left as live and right as neutral. The plug
   itself is round with two round pins measuring 4.8 × 19 mm, spaced 19 mm
   apart and a hole for the socket's earth pin. It will accept Europlug
   and CEE 7/17 plugs.

   As with the German plug below this plug will fit some other types of
   socket either easily or with force. However there is no earth
   connection with such sockets! Also in some cases if the plug is forced
   in, the socket may be damaged when the plug is removed.

Type F (German 2-pin, side clip earth)

   CEE 7/4 (German "Schuko" 16 A/250 V earthed)

   The type F plug, defined in CEE 7/4 and commonly called a " Schuko
   plug", is like type E except that it has two earthing clips on the
   sides of the plug instead of a female earth contact. The Schuko
   connection system is symmetrical and allows live and neutral to be
   reversed. The socket also accepts Europlugs and CEE 7/17 plugs. It
   supplies up to 16 amperes. Above that, equipment must either be wired
   permanently to the mains or connected via another higher power
   connector such as the IEC 309 system.

   "Schuko" is an abbreviation for the German word Schutzkontakt, which
   means "Protective (that is, earthed) contact".

   Gost 7396 (Russian 16 A/250 V earthed)

   The countries of the CIS use a standard plug and socket similar to the
   Schuko standard, defined in Russian Standard Gost 7396. The contacts
   are also 19 mm apart, but the diameter of the pins is 4.0 mm instead of
   4.8 mm. It is possible to insert Russian plugs into Schuko outlets, but
   Russian sockets will not accept type E or F plugs because the holes are
   too small. This socket also accepts Europlugs, but does not accept
   CEE 7/17 plugs because they use the larger pin size.

   Many official standards in Eastern Europe are virtually identical to
   the Schuko standard. One of the protocols governing the reunification
   of Germany required that the DIN and VDE standards would prevail
   without exception, so the former East Germany had to conform to the
   Schuko standard. Most other Eastern European countries use the Schuko
   standard internally but, prior to its collapse, they exported large
   volumes of appliances to the Soviet Union with the Soviet standard plug
   installed. Because of that, many of the Russian plugs found their way
   into other Eastern European countries.

Type E and F hybrid

   CEE 7/7 (French/German 16 A/250 V earthed)

   CEE 7/7 plug
   Enlarge
   CEE 7/7 plug

   In order to bridge the differences between sockets E and F, the CEE 7/7
   plug was developed. It has earthing clips on both sides to connect with
   the CEE 7/4 socket and a female contact to accept the earthing pin of
   the type E socket. Nowadays, when appliances are sold with type E/F
   plugs attached, the plugs are CEE 7/7 and non-rewirable. This means
   that the plugs are now identical between countries like France and
   Germany; only the sockets are different.

   Type E and F plugs that are not compatible with both types of socket
   are only found if a cheap replacement plug has been attached to a cord
   that originally had another plug. Better-quality replacements are
   standard CEE 7/7 and are compatible with both Schuko and French
   standard sockets.

   Note that the CEE 7/7 plug is polarized to prevent the live and neutral
   connections from being reversed when used with a type E outlet, but
   allows polarity reversal when inserted into a type F socket. The plug
   is rated at 16 A. Above that, equipment must either be wired
   permanently to the mains or connected via another higher power
   connector such as the IEC 309 system.

Type G (British 3-pin)

   BS 1363 (British 13 A/250 V earthed and fused)

   BS 1363
   Enlarge
   BS 1363

   The BS 1363 plug, commonly known as a "13-amp plug", is a large plug
   that has three rectangular prongs forming a triangle. Live and neutral
   are 4 × 6 × 18 mm spaced 22 mm apart. 9 mm of insulation over the base
   of the pins prevents people from touching a bare connector while the
   plug is partly inserted. Earth is 4 × 8 × 23 mm.

   The plug is unusual in that it has a fuse inside, for protection, in
   addition to a circuit breaker in the distribution panel. The fuse is
   required to protect the flex, as British wiring standards allow very
   high-current circuits to the socket. Accepted practice is to choose the
   smallest standard fuse (3 A, 5 A, or 13 A) that will allow the
   appliance to function. Using a 13 A fuse on an appliance with thin flex
   is considered bad practice.

   The earth pin is required to open shutters over the live and neutral
   pins on most sockets to prevent children from inserting metal objects
   into them, and also prevents the use of plugs made to other standards.
   On plugs for Class II appliances that do not require an earth, the pin
   is often plastic. It is possible to open the shutters with a
   screwdriver to insert other plug types but this should be avoided as
   such plugs will not have a fuse.

   BS 1363 was published in 1962 and since that time it has gradually
   replaced the earlier standard (type D) ( BS 546). Despite being capable
   of carrying a maximum load of 13 A, it is considered a very safe
   system.

Type H (Israeli 3-pin)

   Two Israeli plugs and one socket. The left plug is the old standard,
   the one on the right is the 1989's revision.
   Enlarge
   Two Israeli plugs and one socket. The left plug is the old standard,
   the one on the right is the 1989's revision.

   SI 32 (Israeli 16 A/250 V earthed)

   This plug, defined in SI 32 (IS16A-R), is unique to Israel and is
   incompatible with all other sockets. It has three flat pins to form a
   Y-shape. "Live" and "Neutral" are spaced 19 mm apart. The type H plug
   is rated at 16 A but in practice the inadequate flat pins cause it to
   overheat when connecting large appliances. In 1989 the SI 32 was
   revised to use three round 4 mm pins in the same locations as the older
   standard. Sockets are manufactured to accept both flat and round pins
   in order to be compatible with both old and new plugs. This also allows
   the type H socket to accommodate type C plugs which are used in Israel
   for non grounded appliances. Older sockets, from about the 1970s have
   both flat and round holes for "Live" and "Neutral" in order to accept
   type C plugs. As of 2006, "pure" type H sockets (for 3 flat pins) that
   do not accept type C plugs are very rare in Israel.

   This plug is also used in the areas controlled by the Palestinian
   National Authority in the West Bank and all of the Gaza Strip.

Type I (Australian/Chinese 2/3-pin)

   Australian switched 3 pin dual power point (socket)

   AS 3112 (Australian 10 A/250 V)

   This plug, used in Australia, New Zealand, and Papua New Guinea, has an
   earthing pin and two flat pins forming an upside down V-shape. There is
   an unearthed version of this plug as well, with no earthing pin. The
   flat blades measure 6.5 × 1.6 mm and are set 30° to the vertical on a
   nominal pitch of 13.7 mm. Australian wall sockets almost always have
   switches on them for extra safety, as in the UK.

   There are several AS/NZS 3112 plug variants, including one with a wider
   earth pin is used for devices drawing up to 15 A; sockets supporting
   this pin will also accept 10 A plugs. Additionally, there exists a 20 A
   variant, in which all three pins are oversized and 25 and 32 A variants
   with the 20 A larger pins and the earthing pin forming an inverted "L"
   for the 25 A and a horizontal "U" for the 32 A (note that the 5
   variants {10; 15; 20; 25 & 32 ampere sockets} will accommodate all the
   plugs that are equal or of a lesser current carring capacity but not a
   higher value; i.e. a 10 A plug will be accommodated by all sockets but
   a 20 A plug will only be accommodated by a 20: 25 and 32 A outlet).

   Australia's standard plug/socket system was originally codified as
   standard C112 (floated provisionally in 1937, and adopted as a formal
   standard in 1938), which was superseded by AS 3112 in 1990. As of 2005,
   the latest major update is AS/NZS 3112:2004, which mandated insulated
   pins by 2005. However, equipment and cords made before 2003 can still
   be used.

   CPCS-CCC (Chinese 10 A/250 V)

   Although the Chinese plug is slightly different (the pins are 1 mm
   longer) the Australian plug can be inserted into the socket used in the
   mainland China. The standard for Chinese plugs and sockets was set out
   in GB 2099.1–1996 and GB 1002–1996. As part of China's commitment for
   entry into the WTO, the new CPCS (Compulsory Product Certification
   System) has been introduced, and compliant Chinese plugs have been
   awarded the CCC (China Compulsory Certification) Mark by this system.
   The plug is three wire, grounded, rated at 10 A, 250 V and used for
   Class 1 applications.

   In China, the sockets are installed upside down, relative to the
   Australian one shown in the picture. However, the positions of the live
   and neutral contacts are reversed from those of the Australian plug.
   With devices conforming to current standards this is not too serious,
   as neutral is generally treated the same as live in appliance design.
   However with older or non-complying equipment this difference can be
   dangerous.

   China also uses American/Japanese "Type A" sockets and plugs for
   Class-II appliances. However, the voltage across the pins of a Chinese
   socket will always be 220, no matter what the plug type.

   IRAM 2073 (Argentinian 10 A/250 V)

   The Argentinian plug is a three-wire, earthed plug rated at 10 A, 250 V
   defined by IRAM and used in Class 1 applications in Argentina and
   Uruguay.

   This plug is similar in appearance to the Australian and Chinese plugs.
   The pin lengths and wiring are the same as those for the Chinese
   version. The most important difference from the Australian plug is that
   the Argentinian plug is wired with the live and neutral contacts
   reversed from those of the Australian plug.

Type J (Swiss 3-pin)

   D

   SEV 1011 (Swiss 10 A/250 V)

   Switzerland has its own standard which is described in SEV 1011.
   (ASE1011/1959 SW10A-R) This plug is similar to the type C europlug
   (CEE 7/16), except that it has an earth pin off to one side. Swiss
   sockets can take Swiss plugs or europlugs (CEE 7/16). This connector
   system is rated for up to 10 amperes. There is also a less common
   variant with 3 square pins rated for 16 A. Above 16 A, equipment must
   either be wired permanently to the electrical supply system with
   appropriate branch circuit protection, or connected to the mains with
   an appropriate high power industrial connector.

   Switzerland also has a two-pin plug, with the same pin shape, size and
   spacing as the SEV 1011's live and neutral pins, but with a more
   flattened hexagonal form. It fits into both Swiss sockets (round and
   hexagonal) and CEE 7/16 sockets, and is rated for up to 10 A.

   IEC 60906-1 (Brazilian 16 A/250 V)

   In 1986, the International Electrotechnical Commission published IEC
   60906-1, the specification for a plug that looks similar but is not
   identical to the Swiss plug. This plug was intended to become one day
   the common standard for all of Europe and other regions with 230 V
   mains but the effort to adopt it as a European Union standard was put
   on hold in the mid 1990s. Brazil — which uses a mix of Europlug,
   Argentine and NEMA plugs — later adopted it as national standard
   NBR 14136 in 2001 and it will be the only plug permitted to be sold
   with domestic appliances in Brazil from 2009.

Type K (Danish 3-pin)

   107-2-D1
   Enlarge
   107-2-D1

   DS Afsnit 107-2-D1 (Danish 10 A/250 V)

   The Danish standard plug is described in DS section 107-2-D1
   (SRAF1962/DB 16/87 DN10A-R). The plug is similar to the type F Schuko
   plug except that it has an earthing pin instead of earthing clips. The
   Danish socket will also accept the type C CEE 7/16 Europlug or type E/F
   CEE 7/17 Schuko-French hybrid plug. Type F CEE 7/4 (Schuko), type E/F
   CEE 7/7 (Schuko-French hybrid), and earthed type E French plugs will
   also fit in the socket but should not be used because the earth contact
   will not connect. A variation of this plug intended for use only on
   surge protected computer circuits has been introduced. The current
   rating on both plugs is 10 A.

   Adapter plugs exist to allow connection of CEE 7/7 prongs to
   non-computer outlets. These usually are not sold at the local
   supermarket so visitors wishing to be safe should contact an
   electrician.

   Since the early 1990s grounded outlets have been required in all new
   electric installations in Denmark.
   23-16/VII with socket
   Enlarge
   23-16/VII with socket
   23-16/VII rewirable
   Enlarge
   23-16/VII rewirable
   Italian power strip showing both types of hybrid socket
   Enlarge
   Italian power strip showing both types of hybrid socket

Type L (Italian 3-pin)

   The Italian earthed plug/socket standard, CEI 23-16/VII, includes two
   models rated at 10 A and 16 A that differ in contact diameter and
   spacing. Both are symmetrical, allowing the live and neutral contacts
   to be inserted in either direction. CEE 7/16 (type C) unearthed
   Europlugs are also in common use, and standardized in Italy as
   CEI 23-5. Appliances with CEE 7/7 Schuko-French plugs are often sold in
   Italy, but not every socket will accept them. Adapters are commonly
   used to connect CEE 7/7 plugs to CEI 23-16/VII sockets.

   CEI 23-16/VII (Italian 10 A/250 V)

   The 10 ampere style extends CEE 7/16 by adding a central earthing pin.
   Thus, CEI 23-16-VII 10 A sockets can accept CEE 7/16 Europlugs. This is
   the plug shown in the illustrations. Outside of Italy, this plug is
   found in Libya, Ethiopia, Chile, various countries in North Africa, and
   occasionally in old buildings in Spain.

   CEI 23-16/VII (Italian 16 A/250 V)

   The 16 ampere style looks like a bigger version of the 10 A style. The
   pins are a couple of millimetres further apart, and all three are
   slightly thicker. The packaging on these plugs in Italy may claim they
   are a "North European" type. They were also referred to as industriale
   ("industrial") although this is not a correct definition.

   Variations in sockets

   Two types of sockets are in common use in modern installations in
   Italy. One type has a central round hole and two 8-shaped holes above
   and below. This design allows the connection of both styles of type L
   plugs (CEI 23-16/VII 10 A and 16 A) and the type C CEE 7/16 Europlug.
   The advantage of this socket type is its small footprint.

   The other type looks like a type F socket, but adds a central grounding
   hole. This design accepts CEE 7/7 (type E/F) plugs, in addition to type
   C and type L 10 A plugs; its disadvantage is that it is twice as large
   as a normal type L socket. Some of these sockets also have extra holes
   to accept type L 16 A plugs.

   Older installations often have sockets that are limited to either the
   10 A or the 16 A style plug, requiring the use of an adapter if the
   other style needs to be connected.

Type M (see D)

   BS 546 (South African 15 A/250 V)

   Type M is sometimes used to describe the 15 A version of the old
   British type D, used in South Africa and elsewhere. See type D for
   details.
   A standard grounded Thai outlet supporting all common 2 pin plugs and
   also earthed american plugs
   Enlarge
   A standard grounded Thai outlet supporting all common 2 pin plugs and
   also earthed american plugs

Multi standard sockets

   Sockets that take a variety of incompatible plug types are often seen
   in developing countries where electrical standards are either lacking
   or unenforced. These sockets may accept both 120 V and 240 V plugs
   raising a significant risk of devices being be damaged by the wrong
   voltage. Sometimes they have one or more earth holes to allow 3 pin
   plugs, but there is a good chance that the ground contact may not
   actually be connected to earth and the ground contact certainly will
   not mate with schuko or french plugs. Great care should be taken to
   avoid incompatible voltage and grounding connections when using such
   outlets. Multi-standard devices designed to auto-adapt to different
   voltage and frequency standards, and which do not require a ground
   contact are best used with these sockets.

   Retrieved from "
   http://en.wikipedia.org/wiki/Domestic_AC_power_plugs_and_sockets"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
