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Power Connector Tutorial

(Information compiled from internal and external sources. Wikipedia.org, etc.)

What is a Power Plug?
A power plug (mains plug) is a connector that fits into a power point or electrical socket. It has male features, usually brass and often tin or nickel plated, that interface mechanically and electrically to the mains. Such plugs have a live contact, a neutral contact, and an optional earth (aka. ground). In many types of plugs there is no distinction between live and neutral and in a few cases both main pins may be live.

What is a Power Socket?
A power socket (electrical socket, power point, mains socket, plug-in, outlet, receptacle, or female power connector) is a connection point that delivers mains electricity when a plug is inserted into it. It is the opposite of a plug, and usually has only female features.

General Info
Most common household power is "single phase". In some countries two live conductors (split phase or two phases from a three phase supply) or even three phases are wired into a home. However in most places only one phase conductor along with the neutral is connected to each household socket. Sockets for three-wire 120/240 volt appliances, with two live connections, a neutral,and ground, are also common in North America.

Connector Types

(used in, among others, North and Central America and Japan)
  • NEMA 1-15 (North American 15 A/125 V ungrounded)
  • JIS C 8303, Class II (Japanese 15 A/100 V ungrounded)
Type A Plug
This class II ungrounded plug with two flat parallel prongs is pretty much standard in most of North and Central America. At first glance, the Japanese plug and socket seem to be identical to this standard. However, the Japanese plug has two identical flat prongs, whereas the US plug has one prong which is slightly larger. Therefore it is no problem to use Japanese plugs in the US, but the opposite does not work often. Furthermore, Japanese standard wire sizes and the resulting current ratings are different than those used on the American continent.
(used in, among others, North and Central America and Japan)
  • NEMA 5-15 (North American 15 A/125 V grounded)
  • JIS C 8303, Class I (Japanese 15 A/100 V grounded)
Type B Plug

This is a class I plug with two flat parallel prongs and a grounding pin (American standard NEMA 5-15/Canadian standard CS22.2, n°42). It is rated at 15 amps and although this plug is also standard in Japan, it is less frequently used than in North America. Consequently, most appliances sold in Japan use a class II ungrounded plug. As is the case with the type A standard, the Japanese type B plugs and sockets are slightly different from their American counterparts.

An ungrounded version of the North American NEMA 5-15 plug is commonly used in Central America and parts of South America. It is therefore common for equipment users to simply cut off the grounding pin that the plug can be mated with a two-pole ungrounded socket.

(used in all countries of Europe except the United Kingdom, Ireland, Cyprus and Malta)
  • CEE 7/16 (Europlug 2.5 A/250 V unearthed)
  • CEE 7/17 (German/French 16 A/250 V unearthed)
  • BS 4573 (UK shaver)
Type C Plug
This two-wire plug is ungrounded and has two round prongs. It is popularly known as the Europlug which is described in CEE 7/16. This is probably the single most widely used international plug. It will mate with any socket that accepts 4.0-4.8 mm round contacts on 19 mm centres. It is commonly used in all countries of Europe except the United Kingdom and Ireland. It is also used in various parts of the developing world. This plug is generally limited for use in class II applications that require 2.5 amps or less. It is, of course, unpolarised.
(used almost exclusively in India, Sri Lanka, Nepal and Namibia)
  • BS 546 (5 A/250 V earthed)
  • BS 546 (15 A/250 V earthed)
Type D Plug
India has standardised on a plug which was originally defined in British Standard 546 (the standard in Great Britain before 1962). Although type D is now almost exclusively used in India, Sri Lanka, Nepal and Namibia, it can still occasionally be found in specialist applications such as hotels and theatres in the UK. This plug has three large round pins in a triangular pattern. It is rated at 5 amps. Type M, which has larger pins and is rated at 15 amps, is used alongside type D for larger appliances in India, Sri Lanka, Nepal and Namibia. Some sockets can take both type M and type D plugs.
(primarily used in France, Belgium, Poland, Slovakia, the Czech Republic, Tunisia and Morocco)
  • French type E
Type C Plug
France, Belgium and some other countries have standardised on a socket which is different from the CEE 7/4 socket (type F) that is standard in Germany and other continental European countries. The reason for incompatibility is that grounding in the E socket is accomplished with a round male pin permanently mounted in the socket. The plug itself is similar to C except that it is round and has the addition of a female contact to accept the grounding pin in the socket. In order to bridge the differences between sockets E and F, the CEE 7/7 plug was developed: it has grounding clips on both sides to mate with the type F socket and a female contact to accept the grounding pin of the type E socket. The original type E plug, which does not have grounding clips, is no longer used, although very rarely it can still be found on some older appliances. Note that the CEE 7/7 plug is polarised when used with a type E outlet. The plug is rated at 16 amps. Above that, equipment must either be wired permanently to the mains or connected via another higher power connector such as the IEC 309 system.
(used in, among others, Germany, Austria, the Netherlands, Sweden, Norway, Finland, Portugal, Spain and Eastern Europe)
  • CEE 7/4 (German "Schuko" 16 A/250 V earhted)
  • Gost 7396 (Russian 10 A/250 V earthed)
Type F Plug

Plug F, known as CEE 7/4 and commonly called "Schuko plug", is similar to C except that it is round and has the addition of two grounding clips on the side of the plug. It has two 4.8 mm round contacts on 19 mm centres. Because the CEE 7/4 plug can be inserted in either direction into the receptacle, the Schuko connection system is unpolarised (i.e. line and neutral are connected at random). It is used in applications up to 16 amps. Above that, equipment must either be wired permanently to the mains or connected via another higher power connector such as the IEC 309 system. In order to bridge the differences between sockets E and F, the CEE 7/7 plug was developed. This plug, which is shown above, has grounding clips on both sides to mate with the type F socket and a female contact to accept the grounding pin of the type E socket. The original type F plug, which does not have this female contact, is still available at the DIY shops but only in a rewireable version.

The Soviet Republics use a standard plug and socket defined in Russian Standard Gost 7396 which is similar to the Schuko standard. Contacts are also on 19 mm centres, but the diameter of this contact is 4.0 mm compared to 4.8 mm which is standard in Continental Europe. It is possible to mate Russian plugs with Schuko outlets, but Russian sockets will not allow to connect type E and F plugs as the outlets have smaller hole diameters than the pins of those two plugs mentioned. Many official standards in Eastern Europe are virtually identical to the Schuko standard. Furthermore, one of the protocols governing the reunification of Germany provided that the DIN and VDE standards would prevail without exception. The former East Germany was required to confirm to the Schuko standard. It appears that most if not all of the Eastern European countries generally use the Schuko standard internally but, until recently, they exported appliances to the Soviet Union with the Soviet standard plug installed. Because the volumes of appliance exports to the Soviet Union were large, the Soviet plug has found its way into use in Eastern Europe as well.

(mainly used in the United Kingdom, Ireland, Cyprus, Malta, Malaysia and Singapore)
  • BS 1363 (British 13 A/230-240 V 50 Hz earthed and fused)
Type G Plug

This plug has three prongs (two flat and one rectangular) that form a triangle. British Standard BS 1363 requires use of a three-wire grounded and fused plug for all connections to the power mains (including class II, two-wire appliances). British power outlets incorporate shutters on line and neutral contacts to prevent someone from pushing a foreign object into the socket.

The British domestic electrical system uses a ring main in the building which is rated for 30 amps (5 amps for lighting rings). Moreover, there is also a fusing in the plug; a cartridge fuse, usually of 3 amps for small appliances like radios etc. and 13 amps for heavy duty appliances such as heaters. Almost everywhere else in the world a spur main system is used. In this system each wall socket, or group of sockets, has a fuse at the main switchboard whereas the plug has none. So if you take some foreign appliance to the UK, you can use an adaptor, but technically it must incorporate the correct value fuse. Most would have a 13 amps one, too big for the computer for example. BS 1363 was published in 1962 and since that time it has gradually replaced the earlier standard plugs and sockets (type D) (BS 546).

(used exclusively in Israel)
  • SI 32 (Israeli 16 A/250 V earthed)
Type H Plug
This plug, defined in SI 32, is unique to Israel. It has two flat prongs like the type B plug, but they form a V-shape rather than being parallel like B plugs. Type H plugs have got a grounding pin as well and are rated at 16 amps. Type H sockets are so shaped as to accommodate type C plugs as well. The slots for the non-grounded prongs have widenings in the middle specifically to allow type C prongs to fit in.
(mainly used in Australia, New Zealand, Papua New Guinea and Argentina)
  • AS 3112 (Australian 10 A/240 V)
  • CPCS-CCC (Chinese 10 A/250 V)
  • IRAM 2073 (Argentinian 10 A/250 V)
Type I Plug
This plug has also a grounding pin and two flat prongs forming a V-shape. There is an ungrounded version of this plug as well, with only two flat V-shaped prongs. Although the above plug looks very similar to the one used in Israel (type H), both plugs are not compatible. Australia’s standard plug/socket system is described in SAA document AS 3112 and is used in applications up to 10 amps. Although there are slight differences, the Australian plug mates with the socket used in the Peoples Republic of China (mainland China).
(used almost exclusively in Switzerland and Liechtenstein)
  • SEV 1011 (Swiss 10 A/250 V)
Type J Plug
Switzerland has its own standard which is described in SEC 1011. This plug is similar to C, except that it has the addition of a grounding pin. This connector system is rated for use in applications up to 10 amps. Above 10 amps, equipment must be either wired permanently to the electrical supply system with appropriate branch circuit protection or connected to the mains with an appropriate high power industrial connector.
(used almost exclusively in Denmark and Greenland)
  • Section 107-2-D1 (Danish 10 A/250 V earthed)
Type K Plug
The Danish standard is described in Afsnit 107-2-D1. The plug is similar to F except that it has a grounding pin instead of grounding clips. The Danish socket will also accept either the CEE 7/4 or CEE 7/7 plugs: however, there is no grounding connection with these plugs because a male ground pin is required on the plug. The correct plug must be used in Denmark for safety reasons. 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 amps.
(used almost exclusively in Italy and randomly found throughout North Africa)
  • CEI 23-16/VII (Italian 10 A/250 V)
  • CEI 23-16/VII (Italian 16 A/250 V)
Type L Plug
The Italian grounded plug/socket standard, CEI 23-16/VII, includes two styles rated at 10 and 16 amps and differ in terms of contact diameter and spacing. The plugs are similar to C except that they are earthed by means of a centre grounding pin. Because they can be inserted in either direction at random, they are unpolarised.
(used almost exclusively in South Africa, Swaziland and Lesotho)
  • BS 546 (South African 15 A/250 V)
Type M Plug
This plug resembles the Indian type D plug, but its pins are much larger. Type M is rated at 15 amps. Although type D is standard in India, Sri Lanka, Nepal and Namibia, type M is also used for larger appliances. Some sockets over there can take both type M and type D plugs.
IEC Connectors
C5 Connector
C5 Connector
C5 Connector
The C5 3-conductor 2.5 A is sometimes colloquially called "Mickey Mouse" (because the cross section looks like the silhouette of the Disney character) or "Clover Leaf".

This connector is seen on some laptop power supplies and portable projectors, and notably on the Apple desktop computer iMac G4.
C7 and C8 Connectors
C7 Connector
C7 Connector

C8 Connector
C8 Connector
The C7 and C8 connectors, with two pins rated at 2.5 A, exist in both polarised and unpolarised versions.

The unpolarised C7 (commonly known as "Figure 8") connector is often used for small cassette recorders and battery/mains operated radios.

The polarised C8 is asymmetrical, with one end rounded similarly to the unpolarised version, and the other squarish. It is used for some full size AV equipment and laptop computer power supplies, video game consoles, and similar double-insulated appliances. Unpolarised C7 connectors can be used with appliances equipped with polarized C8 sockets.
C13 and C14 connectors
C13 Connector
C13 Connector

C14 Connector
C14 Connector
Most desktop personal computers use the ten-amp panel-mounting C14 inlet to attach the mains cord to the power supply, as do many monitors, printers and other peripherals. Many older computers also provide a panel-mounting C13 outlet for powering the monitor. In AT form factor computers this outlet was controlled by the physical power switch. With the arrival of ATX the outlet was usually permanently powered, if present on the chassis.
C15 and C16 connectors
C15 Connector
C15 Connector

C16 Connector
C16 Connector
Some electric kettles and similar hot household appliances use a cord with a C15 line socket, and a matching C16 inlet connector on the appliance. (This has led to the widely used slang of kettle plug and jug plug when referring to C15 and C16 connectors.) These are similar to the C13 and C14 combination but have a higher temperature rating, 120 degrees Celsius rather than 70 degrees Celsius, and a ridge (in the socket) or valley in the plug. In Britain the C15 and C16 connectors have replaced and made obsolete the appliance plug in most applications.

The C15 line socket will fit the C14 inlet, but the C13 will not fit the C16. That is, you can use an electric kettle cord to power a computer, but not a computer cord to power a kettle. The C16 socket has a plastic ridge opposite the earth pin - preventing C13s fitting but C15s have a groove to match. Many people do not notice this subtle distinction and refer to cords with both variants as kettle leads in the United Kingdom, and kettle cords or jug plugs in Australia. The official designation in Europe for the C15 and C16 connectors is 'hot condition' connectors.
C17 and C18 connectors
C17 Connector
C17 Connector

C18 Connector
C18 Connector
Similar to C13 and C14 connectors. However the C17 and C18 do not have a third pin for earthing. A C18 inlet will accept a C13 line socket but a C14 inlet will not accept a C17 line socket.

IBM's Wheelwriter series of electronic typewriters are one common application. Three wire cords with C13 sockets - which are easier to find - are sometimes used in place of the two wire cords for replacement. In this case, the ground wire will not be connected

Another common application is on the power supplies of Xbox 360 games consoles, replacing the C15 and C16 connectors employed initially.
C19 and C20 connectors
C19 Connector
C19 Connector

C20 Connector
C20 Connector
C19 and C20 connectors, with pins rated at 16 A, are used for some server room applications where higher currents are required. For instance, on high-power servers, UPSs, PDUs and similar datacenter equipment. They are similar to C13 and C14 connectors, but rectangular (without chamfered corners) and with the pins rotated so they are parallel to the long axis of the connector.

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