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Generator Sockets: The Basics | PowerMark

Generator Sockets: The Basics

One of the most important components in a Diesel generator, which often gets overlooked (due to its size) is the generator socket. The Diesel generator socket is the contact point between your power solution and your business. Without a power socket connecting your generator to your premises, you’d have no power – so it’s important to know this part well. In this post; we’ll give you a basic overview of Diesel generator sockets, their applied technical information and the benefits of our stocked generator sockets. With this information in hand, you’ll ensure that your choice of generator socket will result in smooth operations.

In Europe and the UK, the most common generator plugs are based upon the IEC 60309 international standards. These plugs are designed to withstand the rigours of industrial work, with a maximum current of 800A, maximum voltage of 1000V and maximum frequency of 500Hz. For comparison, your typical UK power plug is rated at 13 A, and can carry a maximum of 264V.

IEC 60309 Specifications

IEC 60309 sockets are colour coded, so you can ascertain the compatibilities of your plugs and sockets with ease. Here’s a handy table highlighting the colours you are likely to see in many industrial power solutions:

Colour Voltage Range (V) Use Case
White 40-50 Single Phase AC/DC Power
Yellow 100-130 125V Single/Spilt-phase AC Power
Blue 200-250 250V Single/Spilt-phase AC Power
Orange 125/250 125/250V Series II Current Ratings
Gray 277 277V Series II Current Ratings Single-phase AC Power
Red 300-480 400V Spilt-phase AC Power


To ensure that incompatible voltage and frequency combinations are not paired together, your typical generator socket uses a ‘keying’ system based upon your traditional clock. Different voltage and frequency combinations are distinguished by the location of the earth pin or a plastic facsimile known as the minor keyway. The earth pin/minor keyway can be at one of twelve 30 degree intervals , described by clock positions 1h to 12h. The Earth pin has a larger diameter than the other pins, preventing the wrong type of plug being inserted in a socket.

Here are a few of the most common IEC plug types:

  • Blue P+N+E, 6h: the 16A weather-resistant variant is common for caravans, and its 32A version is a prevalent standard in temporary buildings.
  • Yellow P+N+E, 4h: widespread use on British 110V construction sites, colloquially known as the Commando Socket.
  • Red 3P+N+E, 6h: plug allows connecting to the widespread 400 V three-phase power network. The most common ratings are 16 A, 32 A and 63 A. Construction sites in central Europe usually have this three-phase socket type as the single-phase to neutral voltage of 230 V is available for other devices.


Benefits of IEC 60309

IEC 60309 has numerous benefits over other Diesel Generator plug and socket standards

  • Its IP44 rating means you can rest assured in the knowledge that, the socket is resistant to forced or accidental entry from slender screws. The socket also counters entry from wires and is splash-resistant.
  • IEC 60309 devices come in many varieties with differing pin-counts, plug diameters, and voltages. These variable features allow IEC 60309 devices to accommodate any industrial use case, in a familiar and proven form factor.
  • These devices are foolproof, in that a plug of one type can only be inserted into the same type of socket. This reduces the learning curve, potential guesswork and helps keep your workers safe. This also stops expensive equipment being damaged accidentally, which could prove costly.

For high-quality generator sockets, trust PowerMark. We are the number one UK genuine parts supplier. Check out our range of generator sockets today.

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