In Europe the most common range of heavy commercial and industrial plugs are made to IEC 60309 (formerly IEC 309) and BS EN 60309-2 (formerly BS 4343) (the two refer to the same plug types though BS EN specifications tend to be stricter). These are often referred to in the UK as CEE industrial or simply CEE plugs, or as "commando connectors" (presumably after the MK Commando range that contains these connectors).

Voltage is represented by a color code (in three-phase plugs the stated voltage is the phase-phase voltage, not the phase-neutral voltage). The different voltages have the key (or keys in the case of ELV plugs) in different places relative to the earth pin, therefore it is impossible to mate, for instance, a blue plug with a yellow socket. It is also not possible to mate different pin configurations or current ratings, therefore, for example, a 16 A 3P+E 400 V plug will not mate with a 16 A 3P+N+E 400 V socket and a 16 A P+N+E 230 V plug will not mate with a 32 A P+N+E 230 V socket.

The voltage ranges are:

25 V: purple

50 V: white

100-130 V: yellow

200-250 V: blue

346-460 V: red

500-750 V: black

high frequency >50 V: green

Plugs are available in P+N+E (single phase), 3P+E (3 phase no neutral), and 3P+N+E (three phase with neutral). Current ratings available are 16 A, 32 A, 63 A, 125 A and 200 A.

Yellow P+N+E, blue P+N+E, yellow 3P+E, red 3P+E, and red 3P+N+E are by far the most common arrangements. Blue P+N+E sockets (generally 16 A although 32 A is becoming more common) are used near-universally by UK campsites and yacht marinas to provide domestic mains power to caravans or boats; they are also used elsewhere in Europe for the same purpose, though in some countries the local domestic plug is also widely used.

A small number of marinas provide 240 volt single-phase power through a red three-phase connector (breaking the relevant standards in the process). This ensures that only boats that have paid the required fee (and thus obtained an appropriately made-up adaptor cable) are able to use the electricity.
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