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.
Type I is mainly used in Australia, New Zealand, Papua New Guinea, China and Argentina. (Click here for a complete list of all countries that use type I)
This 10 amp plug has two flat 1.6 mm thick blades, set at 30° to the vertical, forming an upside-down V. Their centres are spaced 13.7 mm apart and both prongs measure 17.3 mm in length and 6.3 mm in width. The flat earth blade also measures 6.3 by 1.6 mm, but it is 20 mm long. The distance between the centre of the grounding pin and the middle of the plug is 10.3 mm. There is an ungrounded version of this plug as well, with only two flat V-shaped prongs. Both plug versions have insulated live and neutral pins, so even if the plug is not fully inserted into a socket, touching the exposed part of the prongs can’t give you a shock.
A plug/socket configuration rated at 15 amps is also available, but the ground pin is wider: 8 mm instead of 6.3 mm. A standard 10 amp plug will fit into a 15 amp outlet, but a 15 amp plug only fits this special 15 amp socket. There is also a 20 amp plug whose prongs are wider still. A lower-amperage plug will always fit into a higher-amperage outlet but not vice versa. Australia’s plug/socket system is codified as standard AS 3112. Although there are slight differences (the pins of Chinese plugs are 1 mm longer and the sockets are installed with the earth contact facing upwards), the Australian plug mates with the socket used in the People’s Republic of China (mainland China).
The reason as to why the dimensions of the Australian type I are very similar to those of type A is because the Australasian standard is actually an obsolete type of American plug. It was patented in 1916 by Harvey Hubbell II, the same electrical engineer who had invented the type A plug. Hubbell’s three-blade design never proved popular in the U.S. because of its incompatibility with the existing type A plug, but it was favoured in Australia over the British type D system, because it was easier for local manufacturers to make plugs with flat pins rather than round ones. In the 1930s, the predominant Australian electrical accessory manufacturers, along with the State Electricity Commission of Victoria, decided to standardize on Hubbell’s