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Question about recently fitted split load consumer unit

Discussion in 'Electrics UK' started by iwest, 25 Oct 2004.

  1. iwest

    iwest

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    On Saturday morning I had a split load consumer unit fitted. The electrician found that the consumer unit supplied by his supplier was incorrect and not a true split load unit. He could not source what he wanted but said no problem he could use the one he had (RCD non split load one). What he did was to improvise by cutting the busbar to split the load and then he ran live and neutral cables from the feed side of the main switch to the RCD.

    The problem here is that the RCD side is still live when the main switch is off, and to switch off all the house electrics the main switch has to switched off AND the RCD tripped! Should I tell him to replace it with a proper split load unit or is what he has done OK??

    thanks
     
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  3. securespark

    securespark

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    This sounds dodgy.

    A board should not be adapted or modified unless recommended by the manufacturer: from your description, this is not kosher.

    Furthermore, the way a split-load works is that the isolator cuts power to the whole unit.

    Is he a member of a trade body?

    Ask him to come back and fit what you actually asked for: a split-load board.

    Not a cobbled-together Frankenstein CU.
     
  4. Damocles

    Damocles

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    A split load CU is generally a standard one, with the busbar cut and cables supplying power to the RCD half from the main switch. Only, normally from the switched side of the main switch, not from the feed side. This detail might be corrected without too much trouble, or not, depending on the actual construction.

    Electrically, your installation sounds fine. Except the switch arrangement is not what someone might expect. Is it clearly marked which switch does what?
     
  5. securespark

    securespark

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    Dam, if the guy has taken a bog standard RCD incomer board and mucked it about, that does not sound good!

    I doubt if it would be easy to rectify the problems with the board, and even if it were, quite frankly, I would rather have a piece of kit designed for the job, than one butchered to suit.

    Electrically, your installation sounds fine.

    How can you say this on the strength of a short conversation about a
    CU?
     
  6. Damocles

    Damocles

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    Well maybe the other posts are erring on the side of safety, but there is also not enough evidence to show that the sparks concerned did not do a decent job of splitting the CU he had. No evidence to say that it was unsuitable for this.

    Also he seems to have miraculously obtained an extra isolator and fitted it inside the CU. Maybe he just had a spare one lying about, but maybe this suggests he thought about the problem and sorted it.

    'Butchered to suit' is the technical term for following the manufacturers instructions on converting a non-split to a split?
     
  7. iwest

    iwest

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    It certainly is a neat job, and he tested the RCD for operation and trip time using a digital plug into a socket gadget, so I have no doubts he knew what he was doing. He took the isolator switch from another non-split board he had. The question is - is it acceptable to have the RCD side (sockets and electric shower) still live with the 'main' switch off!
     
  8. ban-all-sheds

    ban-all-sheds

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    What do you think, given the expected function of the "main" switch?

    Hint - the answer is not "yes".
     
  9. plugwash

    plugwash

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    btw its normal to have to cut the busbar when fitting a split load CU

    it seems like there are three problems here (a photo would be helpfull)
    what brand is this CU
    1: rcd side fed from wrong side of incomer
    2: rcd side not wired using correct cabling kit (which comes with special fingers and may be the reason for 1)
    3: split load labeling missing
     
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  11. securespark

    securespark

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    Which is why I reckon this is a bog standard RCD incomer board "Butchered To Suit".

    Piccys, please!!
     
  12. iwest

    iwest

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    Plugwash et al...

    Sorry, photo not possible today but .....The consumer unit is a MEM AD8HE (8 way 100A RCD controlled). The electrician fitted an 100A isolator switch on the left side of the CU, with the RCD on the right side of the CU. He then cut the busbar so that on the left side was central heating/cooker/lights/spare and on the RCD controlled right side was ring main and electric shower. The problem is the tails from the meter join the feed in of the isolator switch, he then took a second pair of tails from the feed of the isolator to the RCD feed. Hence with the main iosolator switch off the RCD is still live, and the ring main and electric shower are live until the RCD is tripped.

    A question I have is can I switch off the power, remove the tails that go from the isolator to the RCD, and (using a MK split load kit) wire from the load (switched side) of the isolator to the RCD and hence the RCD is off when the nain switch is off??
     
  13. breezer

    breezer

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    why should you have to do it? not a relative is he?
     
  14. securespark

    securespark

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    My point exactly, Breeze.

    I point Mr West to my first post: Ask him to return and fit the proper kit.

    BTW, did he give you a cert for the work?
     
  15. dw3101

    dw3101

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    sounds to me like the rcd cables are simply in the wrong side of the main switch.. (everything else aside, which probably is nowhere near as bad as it sounds.)
     
  16. securespark

    securespark

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    I think Mr West has gone, well, er, West........
     
  17. iwest

    iwest

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    Thanks for the replies... The job was done by a friend of a friend as a favout hence my hesitating to get stroppy with him. To be on the safe side I will change it for a proper split load one, I can reuse the MCBs so it should not be too much hassle. I spoke to the MEM technical people and they said the old range could be adapted to be split load, but the one I had shouldn't really be modified.

    Thanks again
    'Mr West'!!
     
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