DIY Doctor

Two consumer units?

Postby jawjaw » Thu Jul 31, 2008 12:55 pm

I am adding a large extension to my house. The existing lighting circuits on the existing consumer unit already have more than 1200Watts of lighting connected to them.

My idea is to fit another consumer unit just to supply the extension. Would this meet the current regulations?

I don't want to upgrade the existing consumer unit as all the circuits connected to it would have to be tested as part of the approvals process!
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Postby ericmark » Thu Jul 31, 2008 5:47 pm

Yes you can fit second consumer unit common when supplying showers and sheds you may have to use two lighting circuits as most light fitting need fusing to 6 amp. There are three ways to connect with henley block or from existing consumer unit and latter with approved cable or twin and earth. Routes are very important as you may need to have RCD at supply end if not approved cable etc. There is a lot involved. See 17th Edition links and also Part P links I am sure once read you will have more questions.

Postby TOPSPARK » Thu Jul 31, 2008 8:27 pm

As a part p registered spark I would recommend using henley blocks and putting your supply tails into these and then new tails from here to both consumer units. a small 6 way split consumer with rcds would do and give you compliance with current 17th edition qiring regs.Also dont forget to take a main earth from one consumer unit to the other. Dont forget this is part p work and notifiable and will then need to be tested and certified
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Postby sparx » Thu Jul 31, 2008 9:57 pm

Hi, you can add another consumer unit but I am led to believe that the old practice of cutting into the tails with Henley blocks is no longer good enough as reg. 537.1.4 implies a single point of isolation is required for each installation. I now use 100A Double Pole isolator as fitted to consumer units in an enclosure with meter tails in one end and consumer units tails out the other.
I have been using up my stock of sw. taken out when fitting RCD's in the past, enclosures cost from £2-£5 & sw about the same so not much more than cost of blocks

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