Type A is used, for instance, in North and Central America and Japan.
This class II ungrounded plug with two flat parallel prongs is pretty much standard in most of North and Central America. It is known as NEMA 1-15 and was invented in 1904 by Harvey Hubbell II. The plug has two flat 1.5 mm thick blades, measuring 15.9 – 18.3 mm in length and spaced 12.7 mm apart. Type A plugs are generally polarised and can only be inserted one way because the two blades do not have the same width. The blade connected to neutral is 7.9 mm wide and the hot blade is 6.3 mm wide. This plug is rated at 15 A.
Type M is used almost exclusively in South Africa, Swaziland and Lesotho.
This plug resembles the Indian type D plug, but its pins are much larger. Type M is a 15 amp plug, and it has three round prongs that form a triangle. The central earth pin is 28.6 mm long and has a diameter of 8.7 mm. The 7.1 mm line and neutral pins are 18.6 mm long, on centres spaced 25.4 mm apart. The centre-to-centre distance between the grounding pin and the middle of the imaginary line connecting the two power pins is 28.6 mm. The South African version of the M plug often has insulated sleeves on the pins to prevent accidental contact with a bare connector while the plug is partially inserted. Although type D is used in India, Sri Lanka and Nepal, type M is also used for larger appliances. Some sockets over there can take both type M and type D plugs. Type M is also used in Israel and the United Arab Emirates for heavy appliances such as air-conditioning circuits (in cases where wall-mounted units are plugged in to a dedicated socket) and certain types of washing machines. In the UK, type M is still pretty much the standard plug for theatre installations, despite efforts to move to the international blue- and red-coloured industrial CEE plugs
Type K is used almost exclusively in Denmark and Greenland.
The Danish standard is described in DS 60884-2-D1. Unlike the similar type E plug, the grounding pin is not mounted in the receptacle, but it is on the plug itself. The U-shaped earthing pin is 14 mm long, 4 mm thick and has a 6.5 mm diameter. The line and the neutral pins of type K are round and have a 4.8 mm diameter. They are 19 mm in length and their centres are spaced 19 mm apart. The centre-to-centre distance between the earth pin and the middle of the imaginary line connecting the two power pins is 13 mm. The plug is rated at 16 A. A type C plug fits perfectly into a type K socket. The Danish socket will also accept plug types E and F: however, there is no grounding connection with these plugs because a male ground pin is required on the plug. Because of the huge amount of imported European appliances fitted with E/F plugs, the Danish government decided to make it legal to install type E or F sockets too. So, the expectation is that, in the long term, the standard European type F socket (or – but this is less likely – the less frequently used type E) will eventually replace the Danish type K socket
Type E is primarily used in France, Belgium, Poland, Slovakia, the Czech Republic, Tunisia and Morocco.
France, Belgium and some other countries have standardized 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, which is permanently mounted in the socket. This earth pin is 14 mm long and has a diameter of 4.8 mm. The plug itself is similar to C except that it is round and has the addition of a female contact to accept the socket’s grounding pin. The plug has two 4.8 mm round pins, measuring 19 mm in length on centres spaced 19 mm apart. The centre-to-centre distance between the female contact and the middle of the imaginary line connecting the two power pins is 10 mm.
In order to bridge the differences between sockets E and F, the CEE 7/7 plug was developed (see photo on the left): 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 60309 system. A type C plug fits perfectly into a type E socket. The socket is recessed by 15 mm, so partially inserted plugs do not present a shock hazard.
Below is a complete overview of all countries of the world and their respective plugs/outlets and voltages/frequencies used for domestic appliances. The table shows that in most countries the mains supply is between 220 and 240 volts (50 or 60 Hz); countries that operate on 100-127 volts are greatly outnumbered. The list also reveals that types A and C are the most frequently used electric plugs worldwide.