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IEC 60309: Wikis


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In the foreground, a downward-angled industrial wall socket with a red cap, mounted to a wall; a red plug is inserted into it. In the background, another similar connection.
Two IEC-60309-style plugs inserted into wall-mounted sockets

IEC 60309 (formerly IEC 309) is an international standard from the International Electrotechnical Commission for "plugs, socket-outlets and couplers for industrial purposes". The highest voltage allowed by the standard is 690 V DC or AC; the highest current, 250 A; and the highest frequency, 500 Hz. The temperature range is −25 °C to 40 °C.

IEC 60309-1 specifies general functional and safety requirements for any form of industrial high-current power connector. IEC 60309-2 specifies a range of mains power connectors with circular housings, and different numbers and arrangements of pins for different applications. IEC 60309-3 dealt with connectors for use in explosive gas environments, but was withdrawn in 1998. IEC 60309-4 concerns switched socket-outlets and connector interlocks. In the United Kingdom, this standard was first adopted as BS 4343:1968 and has since been replaced by its European equivalent EN 60309:1999, catalogued in the BSI system as BS EN 60309:1999. In the U.K. these plugs are often referred to as Commando, CEE industrial, CEEform or simply CEE plugs.



Two power cables, each with a 3P + N + E plug at one end, and a matching socket at the other end. The upper cable has blue connectors; the lower cable has red connectors.
Cables with 3P + N + E connectors

IEC 60309 plugs and sockets are identified by colour. For typical installations (where the frequency is 50 Hz or 60 Hz), the coding is based on the voltage (phase-to-phase voltage in the case of multi-phase installations). For higher frequencies, green connectors are used.

Characteristic Colour
20 V – 25 V Purple
40 V – 50 V White
100 V – 130 V Yellow
200 V – 250 V Blue
380 V – 480 V Red
500 V – 690 V Black
> 60 Hz – 500 Hz Green
None of the above Grey


32A 400V 3P+N+Schutzklasse 1 fett.svg 6h Plug
Mated 16 A plug and wall-mounted socket

IEC 60309-2 connectors are produced in many variants, designed so that a plug of one type can only be inserted into a socket of the same type. Different current ratings (such as 16 A, 32 A, 63 A and 125 A) are distinguished by different diameters of the circular housing.

Different voltage and frequency combinations are distinguished by the location of the ground pin (or a plastic projection called the minor keyway, for connectors with no ground pin), as shown in the following table. The ground pin can be in one of twelve locations spaced at 30° intervals around the circle on which all the pins lie. Position 6 is at the same angle as the major keyway, a projection on the plug casing that aligns with a notch on the socket. The ground pin has a larger diameter than the other pins, preventing the wrong type of plug being inserted in a socket.

Number of pins (P=Power, N=Neutral, E=Earth or Ground)
P+N+E/2P+E 3P+E 3P+N+E
2 >50 V, 300–500 Hz, green housing >50 V, 300–500 Hz, green housing >50 V, 300–500 Hz, green housing
3 50-250 V AC 380 V, 50 Hz
440 V, 60 Hz
220/380 V, 50 Hz
250/440 V, 60 Hz
4 100-130 V AC, yellow housing 100-130 V AC, yellow housing 57/100 - 75/130 V AC, yellow housing
5 277 V, 60 Hz 600-690 V AC, black housing 347/600 - 400/690 V AC, black housing
6 200-250 V AC, blue housing 380-415 V AC, red housing 200/346 - 240/415 V AC, red housing
7 480-500 V AC, black housing 480-500 V AC, black housing 277/480 V - 288/500 V AC, black housing
8 250 V DC - -
9 380-415 V AC, red housing 200-250 V AC, blue housing 120/208 V - 144/250 V AC, blue housing
10 - >50 V, 100–300 Hz, green housing -
11 - 440-460 V, 60 Hz, red housing 250/440 V - 265/460 V, 60 Hz, red housing
12 - - -

A six-phase plus earth (6P+E) version also exists.

Common plugs

phase swap plug

The red 3P+N+E, 6h plug is the most common connector as it allows to connect to the widespread 400 V three phase power network that reaches many domestic places. The most common ratings are 16 A, 32 A and 63 A - only in some cases the higher specifications of 125 A and 200 A is used. The five pins are positioned in a circle with the ground connector E to be thicker and longer than the network pins. When looking at the socket the three hot pins L1, L2, L3 are supposed to make for a clockwise turn, i.e. to have their high in the order L1 first, then L2, and L3 last. As some domestic wiring does not support this assumption (which could make some motors to turn backwards) many machines on construction sites feature a phase swap plug that allows to swap two pins. Although not actually allowed by the standard in some wiring setups the N neutral pin is not connected - for their usual occurrence often called farmer three phase (German "Bauerndrehstrom").

The blue P+N+E, 6h plug is a single phase connector that replaces other 230 V domestic plugs. It is especially common in camping vehicles and sockets to be found in caravan parks and yacht marinas throughout Europe including the British isles. It is used since the plain IEC 60309 plugs are inherently safe to standard IP44 and when sockets are mounted looking downwards then the connector system reaches IP53 that is safe to use in outdoor settings under all weather conditions.

See also


en:Industrial and multiphase power plugs and sockets



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