Replacing Consumer Unit

[Peter Ramm]

I am going to replace two existing old "fuse box" consumer units (in the garage) with a new MK Sentry 12-way split load unit.

One of the existing fuse boxes is about 15 inches below the ceiling - but the other is about 3 inches below the ceiling and separated laterally from the other box by about 18 inches.

There is no slack in cables coming from the ceiling void.

The problem: I can fit the new CU close to the ceiling - distance governed by shortest cable going in to ceiling void - but it is going to be a bugger to work on.

Could I mount some sort of covered terminal blocks next to the ceiling (cables then going from terminal blocks straight in to ceiling void) with the terminal block(s) fed from CU.

I can see it will be a neat solution and easy to work on if it is permissible.

Any suggestions?

[Andy Hall]

First on the subject of the CU itself, the MK ones are excellent - I've used several of them in different applications together with their breakers etc. If you are buying a bunch of stuff, it is worth going along to an electrical wholesaler and negotiating a discount. Consider going for a larger CU if 12 only just covers it. The incremental cost is negligible and far better than kicking yourself later when you want to add something.

For the connections, you could do the required extensions in a number of ways. One would be to fit an enclosure with DIN rail close to the ceiling and use DIN rail terminals, one per conductor. Another would be to use crimp connectors, again one per conductor.

In either case, it's very important to take care with connections and preferably to number them with cable identifiers to ensure that you don't mix connections to different circuits.

If you do any bunching together of cables (e.g. with conduits or ducts), read the IEE Wiring Regulations tables carefully to ensure that you don't exceed ratings.

.andy

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[Peter Ramm]

Excellent - many thanks.