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Plug and socket specification - top tips

Joe Bush, Editor


Tags: Cables & Accessories

Topics: Cables & Accessories

Caroline Boden of Legrand talks to Electrical Engineering about the processes involved in ensuring the correct and best specification of industrial plugs and sockets to meet the robust needs of industrial installations

The consequences of incorrectly specifying electrical products can be severe - to the extent where it could even endanger life. The challenge of getting specification right is made even more extreme in industrial installations, which tend to require more robust solutions than in a commercial or residential project, and that present some unique challenges.

It is important in these environments that specifiers seek out the best solution in terms of electrical performance, ease of installation and lifetime cost. They also need to take into consideration product durability, robustness, connection reliability and safety.

This means that there are very different specification rules for industrial installations and ensuring every single specialist need is met can be challenging for even the most experienced specifier. To lend a helping hand in these environments, Legrand has compiled ten top tips for specifying industrial plugs and sockets.

1. Be protected

All industrial plugs and sockets have a protection classification in terms of IP (protection against solid bodies and liquids) and IK (protection against mechanical impact). Therefore, it’s important to choose the product with the correct IP and IK rating for the application and environment in which the products will be used.

2. Material cost

Clearly the choice of material (metal or plastic) can have an impact on cost - metal products are generally more expensive but are more durable and have a higher IK rating for high impact resistance and robustness. It is also important to consider the environment too as an over specified metal product will cost more than is necessary, while an under specified plastic product may well be damaged too easily and so reduce the lifespan of the installation.

3. The right angle

It is important to bear in mind and consider angled rather that straight plugs, expecially in situations where there are either cabling space restraints or applications requiring 63A and 125A products, as the handle on the angled plug facilitates easy removal from the socket.

4. Mounting options

Sockets are available in both surface and panel mounting options, with the panel mounting variant allowing an industrial socket to be installed into an enclosure or panel, while surface mounting enables installation onto any solid surface using a rigid conduit.

5. Security

Products with padlockable covers are now readily available which help prevent unauthorised usage and provide increased safety during maintenance.

6. Temperature

There are temperature limitations to industrial plugs and sockets so the wider the temperature range the wider the appeal in terms of installation environment. Specifying a product with an incorrect operating temperature may result in degradation of the product and may cut short operating life. Therefore, it is vital to align the temperature to the installation environment.

7. Fixing

The material of the screws and contact sleeves for the products is an important consideration, as different materials have different benefits. For example, brass contact sleeves help ensure high quality, reliable connections, while stainless steel screws provide maximum durability and high corrosion resistance.

8. Combinations

For installations where there are space constraints, combined industrial switch sockets are well suited as they provide the features of two products within one unit, thus saving both time and costs.

9. Safety

When industrial plugs and sockets are being used in a facility where employees are in contact with machinery and power supplies, safety is paramount.  The Hypra Prisinter sockets from Legrand, have an interlocked load break system, meaning the plug has no power until it is quarter turned and interlocked into place. Subsequently the isolation switch must be pressed, thus disconnecting the power, before the plug can be removed from the socket.

10. Auxiliaries

In applications where remote indication or the introduction of a secondary device is required, products like Prisinter provide a solution. Push-in auxiliary contacts can be fitted, which work in conjunction with the main contacts to provide remote indication of the device’s status. They can also be utilised to provide start-up for a support product e.g. in high temperature environments where a cooling fan must be activated at the same time as the circuit being fed, or in dusty zones where ventilation is required simultaneously to support the primary circuit.


Some of these tips may not seem like rocket science, but they don’t need to be, they just need to be considered. Getting a specification absolutely right not only helps in terms of cost, installation speed and end user safety, but goes a long way in helping to provide system and product integrity along with an extended product life cycle.



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