Secondary consumer unit

[Mark]

Hello, I want to install a secondary consumer unit so that I can do some outdoor wiring. I'm happy with the technicalities of how to wire from the consumer unit.

But,can anyone tell me in practical terms how to connect the secondary unit to the incoming mains and what parts to use. I thought I would simply be able run some wires from primary CU to the secondary by inserting some new wires into the same terminals as the incoming supply on the primary CU but of course 2 wires this size won't fit into the terminal holes.

Can I fit a terminal box and tap into the incoming wires?

Any help and advice on what parts to use and buy would be greatly appreciated. I am assumming I have to 25mm sq cable for the new consumer unit incoming supply.

How much would it cost apporxiamtely to get the electricity board to come and connect the secondary unit? Thanks.

[Andy Hall]

Yes you can.

You need a service connector block. e.g. MK1100

are also colloquially known as "Henley blocks" after the most well known brand.

Needless to say, the power needs to be disconnected. Removing the fuse at the meter position is the normal way to do this. It was considered technically to be illegal to remove the fuse seal, but nowadays, electricity suppliers appear to be relaxed about this as long as you don't touch the separate meter seals.

You could also consider fitting an isolating switch in front of this to allow for future work.

You would need to ask them since prices seem to vary a lot.

.andy

To email, substitute .nospam with .gl

[Tinklemagoo]

to allow for future work.<

Scottish Power supplied and fitted free the above switch box free of charge Oct 99.

[stefek.zaba]

I couldn't tell from your description whether the secondary CU is going to be nice and close to the existing CU and the main service fuse. If it is, the Henley block is the way to go, and the 100A isolating switch is a Good Thing too. But if the secondary CU is some distance away (more than a couple of metres), it's both too expensive and not safe to run gert long 25mmsq tails to it relying only on the service fuse to protect them. Rather, you'll want to take a sensibly-rated way out of your main CU (30A, 40A, in the extreme 63A) and feed your physically-remote CU for the outdoor circuits via a suitable "submain" cable - depending on max loading, distance, need for mechanical protection and so on, that could be beefy twin-and-earth (6 or 10mmsq), SWA, or the useful halfway house of Supertuff.

"Normal" circuit-design calculations will tell you what cable and overcurrent protection to use.

HTH, Stefek

[Mark]

Thanks everyone for your help. I know what to do now. Cheers, Mark

[Rick Dipper]

You need to turn the power off, probably by pulling the lecie borad fuse.

You then use a connector box (screwfix) to make the meter tails (Screwfix) into a "T" shape, one set to each consumer unit.

You have to be real carefull that you get it right, cause you need the lecie board round to refit the tag on the fuse.

Rick