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Confirming system and install

Discussion in 'Electrics UK' started by Donald welsh, 3 Jul 2020.

  1. Donald welsh

    Donald welsh

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    Hi all been requested to install a shower into house first time I have not had spare fuse in situe normal just stick to upgrading replacing current systems ins fuse system is BS3871 no extra fuse in spare slot so the obvious choice is installing a second consumer unit.
    I reckon the system is a TN-S system see picture attached.
    looking at adding Henley blocks 25mm tails from meter side to both consumer units and 16mm earth to earth block.
    The 1way CU will have 63amp RCD and a 40amp for the 9kw shower.
    10mm cable to 40amp double pole switch installed in cupboard.
    Obviously the main fuse will have to be pulled for safety. Is the above the only option to me or is Thier another option without pulling the fuse that will still comply to BS7671 and be safe.
    Any advice is much appreciated
     

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  3. EFLImpudence

    EFLImpudence

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    You are not allowed to pull the main fuse.

    Why have you been requested?
     
  4. conny

    conny

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    The fact that you say, "I reckon the system is a TN-S system see picture attached." fills me with dread.

    If you are electrically competent surely you should KNOW what system it is, rather than RECKON?
    Is the picture included in the hope someone will confirm your reckoning or state that it is actually something different?
     
  5. Taylortwocities

    Taylortwocities

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    Ooh look. Somebody actually has one of those so-called “smart” meters.
     
  6. 333rocky333

    333rocky333

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    Bs3871 are old Mcbs and not fuses either
     
  7. ericmark

    ericmark

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    It does seem to be TN however as to if TN-S or TN-C-S only the DNO can tell you that, not that it really matters that much, so a smart meter will send a signal back if supply fails so really you can't draw the DNO fuse without them knowing, so you clearly need an isolator or other method to remove supply to work on it, and re-instating old systems presents a problem, your going to have to sign to say you have worked on the system and it complies with current edition.

    I have heard the argument that the DNO should provide an isolator so you can isolate else where, so if they are breaking rules why shouldn't I so I will draw the fuse, however two wrongs don't make a right, and although some times the DNO do seem to turn a blind eye to fuse removal that is not always the case.

    What I have done in the past is feed a second consumer unit from first one using the largest MCB that will fit, however since then we have gone to RCD protection of all circuits and metal consumer units, however since either you are a scheme member or have notified the LABC the way forward if uncertain is to ask your scheme provider or LABC inspector, not ask on a forum. You pay a lot of money to the scheme provider so why not use them?
     
  8. bernardgreen

    bernardgreen

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    Get an electrician to do the work.........
     
  9. ericmark

    ericmark

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    I had assumed he was an electrician, you don't do work for other people without being insured, and to get the insurance you would need some qualification. I had been working as an industrial electrician for over a decade before I came to work on my first house as a professional, and had I done workmanship like found in the house in the factory I would have been sacked, it was completely different to what I had been use to, allowed to put three wires in a terminal. And had a guy with me with a stuck gramophone needle saying "the 16th Edition says". I wanted to shove that 16th Edition down his throat.

    We all from time to time come across some thing new, I have been lucky, father and father-in-law in the same trade, but to be Frank if I came to a Smart meter where I know there is going to be a message sent to supplier if I tamper with it, I would want to call a friend and ask off the record what to do. But this is the point some one working in the same area may know how the DNO acts in that area, but on a public forum you simply should not ask the question, no one in their right mind is ever going to tell some one on a public forum to break the law.

    I see many quads on the road around here with no number plate, clearly a farm vehicle basic crossing the road, I am now in Mid Wales, but in North Wales no one would dare do that, the Police would soon be feeling your collar, the same applies to removing DNO fuses, I know in some areas you can get away with it, but not all, anywhere where there has been electric theft in the past, they would not let you get away with breaking the rules, but your scheme provider will likely know, and with a voice reply you have some idea of if he means what he says, or if you should read between the lines.

    Personally I would not want to pull the DNO fuse, even if a scheme member, and if working illegal in the first place, then it would be silly to draw attention to the fact your doing illegal work.
     
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  11. bernardgreen

    bernardgreen

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    It is worrying that people who are acting in the role of "tradesperson" are asking for advice on a DIY forum.
     
  12. gman76

    gman76

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    I wonder where the red wire is going?
     
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  13. sparkwright

    sparkwright

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    In a taped up connector block behind the board most likely :D.
     
  14. gman76

    gman76

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    Or a grow room! :whistle:
     
  15. Donald welsh

    Donald welsh

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    My question may have sent mixed message. I would call local DNO regarding fuze. The consumer unit MCB are BS3871which are no longer allowed as per BS7671, is the best option fitting a 1way CU 63amp RCD and a 40amp for the 9kw shower.
    10mm cable to 40amp double pole switch installed in cupboard.
    Fitting new tails via Henley blocks for new CU or is Thier another way to install the system. Trying to keep costs down for customer if i can. I'm still learning after passing exams so just thought someone might know a different solution
    Thanks


    Read more: https://www.diynot.com/diy/threads/confirming-system-and-install.548346/#ixzz6RE50sMgd
     
  16. flameport

    flameport

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    It's one option.
    There may be others.
    All depends on what's already installed and what the existing consumer unit is and has in it.
    Whether this shower can be installed also depends on the existing installation loads and the rating of the supply.
    A lot more information is required.
     
  17. sparkwright

    sparkwright

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    A picture of the consumer unit would be interesting.
     
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