Museum of Plugs and Sockets logo, small IEC 60309 industrial standard
Basic information of plugs and sockets
navigation icon navigation icon navigation icon


In the 1960s the IECEE (International Commission on the Rules for the Approval of Electrical Equipment) has defined the CEE 17 standard for plugs and sockets for industrial purpose. CEE is an abbreviation of Certification of Electrical Equipment.
CEE17 has been superseded by IEC 309 in 1983, and later renamed IEC 60309 standard (IEC = International Electrotechnical Commission).

In the UK the IEC 309 standard was adopted as BS 4343 in 1968, and replaced by BS EN 60309 in 1999.

There are many types of IEC 60309 sockets, outlets, plugs, connectors and application inlets. They differ with respect to
voltage, current, frequency rating and number of pins.
All plugs and sockets have a protective earth (PE) connection.

An important feature of IEC 60309 is that for each type of plug only one matching socket exists. Any potential dangererous mis-connection is impossible. Details are given below.

Material in the museum collection is shown on a separate page.


IEC60309 16A-6h-3P Plug and Connector
IEC60309 6A-6h-5P Plug and Connector

1, 2
IEC 60309 16A-6h 230V single phase (blue) and 16A-6h 380-415V 3-phase (red} connectors and plugs.
These single- and three-phase plugs are frequently used IEC 60309 devices in workshops, campings, marinas etc. in
countries with a 220-240 Volt standard domestic power.

Basic features of IEC 60309 plugs and sockets ensuring that each plug type matches with only one socket type are keying (position of earth contact) and size of plugs and pins.
Colour codes are helpful to identify different groups of plugs and sockets, in particular with respect to voltage ratings.
Dozens of IEC60309 types exist; they can be arranged in a clock-shaped display.


IEC60309 4h socket
EC60309 4h, 6h and 9h sockets.jpg
IEC60309 9h socket.

3 - 5
IEC 60309 plugs have a key; see image no. 4, top (red) plug. Sockets have a matching - invariable down facing - keyway; see grey and red sockets. Key and keyway assures that there is only one position in which a plug can be inserted in a socket.

Plugs have round pins, arranged in a circle. The diameter of the protective earth pin is always 2 mm larger than the other pins.
Position of the larger earth pin may vary between different types of plugs. The circle of pins can be regarded as a clock. A down facing earth pin (red plug) has a six o'clock (6h) position.
The grey socket (image no. 3) accepts only 3-pin plugs with a 4h earth pin position. The blue plug shown in image no. 1 does not fix in socket no. 3 (although plug and socket sizes of nos 1 and 4 are identical). The 32A socket (no. 5) is compatible only with a 9h socket (that also has the correct size).


IEC 60309 socket and plug sizes

6 IEC 60309 plug size vary according to number of pins (3, 4 or 5) and current (compare 5-pin 16A and 32A).
Pin diameter of 16A is 5 mm (L and N), and 7 mm (earth pin). Pin length (L, N and PE) is 37 mm.
Sizes for 32A: pin diameter is 6 mm (L, N) and 8 mm (PE}; pin length 45 mm (L, N and PE).

Much larger 63A and 125A plugs are shown on a separate page.

Colour codes

100 - 130 Volt AC

120/240 V split phase 60Hz (N.Am. only)
200 - 250 V 
>50 V DC
380 - 480 V 
277 V 60 Hz (N.Am. only)
490 - 690 V 
100 - 500 Hz (among others used in aircrafts)
Colour codes refer to IEC 60309 devices rated at >50 Volt. The colour code of sockets and appliance inlets is often restricted to the cover; see for example sockets shown in image nos 3 and 5.
Unless stated otherwise AC refers to both 50 and 60 Hz.


Types of IEC 60309 sockets ordered according earth pin location (1-12 hour) and number of pins.
Extra Low Voltage (<50V) sockets are not included in the scheme; they have a different key system.

IEC 60309 coloue code and keyway map

IEC 60309 socket and locked plug
IEC 50309 devices have a protection grade of either IP44 or IP67.

IP44 splash-proof socket outlets and connector plugs have a spring loaded hinged cap. When a plug is inserted, the cap hooks over a lug on the plug and retains it in place. See image left.

IP 67 waterproof outlets have a gasket and twist-lock ring which seals outlet and plug together.


Wikipedia     Farnell     Mennekes     Scame 


Navigation icon D i g i t a l   M u s e u m   o f Navigation icon P l u g s   a n d   S o c k e t s Navigation icon