There is now such a wide range of UK consumer units or fuse boards, that choosing the right one for your project can be bewildering. This jargon busting article will help the domestic buyer.

‘Number of Ways’

The first consideration in choosing a consumer unit is deciding how many separate circuits you have. For example, Upstairs Ring Main (main power circuit), Downtairs Ring Main, Upstairs Lighting, Downstairs Lighting, Cooker, Shower, Smoke Alarms, Freezer etc etc. These are all separate circuits.

In the fuse board these circuits are protected by one of two ‘protection devices’; either an MCB or RCBO. The amount of these devices that a consumer unit can take is known as the ‘Number of Usable Ways’. (Protection Devices are discussed in my article ‘Consumer Units and Accessories – A Glossary)

So, quite simply a 10 way consumer unit means there are 10 usable ways which can take 10 MCBs or RCBOs and consequently will protect 10 separate circuits.

The Five Basic Types of Domestic Consumer Unit

Main Switch CUs- Supplied with 100A Main Switch only

Split Load CUs – Supplied with Main Switch and 1 RCD

Dual RCD CUs / 17th Edition CUs – A fuse board with 2 x RCDs and Main Switch

High Integrity Boards – These feature 3 neutral bars and offer far superior circuit separation, by allowing for the fitting of two banks of RCD protected MCBs and one bank of RCBOs, thus negating ‘nuisance tripping’.

Metal or Plastic?

This is fairly simply answered by ascertaining where the fuse board is intended to be situated. If, as is normal, it’s going in the house it’s normal to use plastic, which is also known as ‘insulated’. If it’s to be sited in an outhouse, workshop or garage then its common to use metal. There are no rules governing this and is just a matter of preference. However, in cases where an armoured cable is to be terminated in the fuse board then metal should be used as a plastic unit will snap under the load.

Which Manufacturer?

It seems that every man and his dog is now producing fuse boards and at ever lower prices. To be honest I would steer clear of anything that isn’t manufactured by a circuit protection specialist.

It’s not that anything the newer manufacturers make is unsafe, but there is no guarantee that in years to come these cheaper unbranded units will still be in production; which gives you a big problem if you need replacement MCBs.

The most respected names in the industry, such as Wyex, Hager, MK Sentry or Crabtree have been around for years, put huge investment into research and development and offer a far greater range of protection devices and accessories.

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