New CU required because wiring chased less than 50mm in walls?

Discussion in 'Electricians' Talk' started by rogerk101, Feb 19, 2021.

  1. rogerk101

    rogerk101 Screwfix Select

    I've just had an EICR done for a rental house I own and was surprised to learn that the CU needs to be changed because the wiring for the lighting circuits is shallower than 50mm in the walls.
    Apparently because the lighting wiring is shallower than 50mm in the walls, and they're currently on the non-RCD side of the CU, this warranted a C2.
    I don't mind changing the CU if this is necessary but just wanted to double check here that this is indeed the case.
  2. Peterdevon

    Peterdevon Active Member

    No it is only a C3 it was only a few years ago the 16th edition was the norm, if you don't get any here get the test done by someone sensible.
  3. Bogle Crag

    Bogle Crag Screwfix Select

    Sounds like your electrician is trying to generate some work
    BiancoTheGiraffe likes this.
  4. Comlec

    Comlec Screwfix Select

    18th edition requires new lighting circuits to be RCD protected.
    So work is not required but nothing wrong with bringing up to current standards if you choose.
  5. metrokitchens

    metrokitchens Screwfix Select

    Perhaps the bathroom does not have supplementary bonding and this was the best solution. Just a thought - but I’m not an electrician.
  6. MGW

    MGW Screwfix Select

    Every edition of wiring regulations has a date, which anything designed after that date must comply, but anything designed before that date does not change, remember design date not completion date, so keeping to same design i.e. like for like, if the installation complied when designed it still complies.

    However the EICR had the complies with current edition of wiring regulations code 4 removed, it was deemed to be unhelpful, so we have C1 = dangerous, C2 = potentially dangerous, and C3 = improvement recommended. And these are not linked to the regulations although we do use the regulations as a guide.

    As time has moved on things have changed, for example, lawn mower, so back in 60's the lawn mower was not electric, so with so little electric used in the garden we did not need earth leakage circuit breakers, even if they were made, and there have also been errors, the ELCB-v was rather useless, and was replaced with the ELCB-c so no if buts or maybes a TT installation today with an ELCB-v is potentially dangerous even if that was what was asked for by the regulations when built.

    So today a car charging point fed from a RCD type AC feeding many circuits with a TT supply would be potentially dangerous as the DC component used by car charger can stop the RCD working. But it would not be considered as potentially dangerous with a TN supply, or if it only supplied the car charging unit which has its own built in RCD.

    As to other things the inspector has to decide if potentially dangerous, so if the rental agreement says the tenant is not permitted to drill the walls, how can cables under 50 mm be potentially dangerous, in fact if the cables are in safe zones, again how can it be potentially dangerous, if it were the name would be permitted zones, not safe zones.

    So with a TN supply it is hard to say even with no RCD's that it is potentially dangerous, unless the bonding has been omitted (bathrooms) which is only permitted if RCD protected, or it supplies items used outside.

    However the big question is would you do without RCD protection in your own home, it was one of the first things I added when I moved, so if you want it in your own home, should you not also fit it in rental property. The death of Emma Shaw was not blamed on lack of RCD protection, however it is clear with RCD protection she would not have died.
  7. The Happy Builder

    The Happy Builder Screwfix Select

    Don’t rush into having a go at the electrician as I can refer you to guidance to say he is correct in coding the cables as C2.

    I need to check another book that’s at home, not in the van where I am at the moment as I think the guidance has been changed with the publication of the 18th Edition. If it were a new installation installed to the 18th it would definitely be a C2.

    Refer to BS7671 The Wiring Regulations 522.6.202-204 and see what it says.
  8. Comlec

    Comlec Screwfix Select

    there you go
    MGW likes this.
  9. MGW

    MGW Screwfix Select

    I see 522.6.203 stops a repeat of the Emma Shaw death. Since we can show it was potentially dangerous by the fact Emma Shaw died, it would seem there is not a reasonable argument against being given a C2.
  10. BiancoTheGiraffe

    BiancoTheGiraffe Screwfix Select

    Any reason why they can't just swap put in a RCBO in for the lighting circuit?
    Bazza likes this.
  11. Nomenklatura

    Nomenklatura Active Member

    Do we know that in this case the walls have an internal construction which includes metallic parts?
  12. Nomenklatura

    Nomenklatura Active Member

    Not enough money in it?
  13. rogerk101

    rogerk101 Screwfix Select

    The existing CU is made by Contactum, is already stuffed full, and only has a single 63A RCD.
    Rather than go for a dual RCD metal CU, I might as well bite the bullet and get a metal CU with SPD and RCBOs throughout.
    He also issued a C2 for the lack of visible supplemental bonding in the bathroom, which would be addressed with the new CU.
    I was surprised by C2s for the two bathroom extractor fan isolating switches mounted in the ceilings above the doorways entering each bathroom (he says they need to be pull switches, not rocker switches).
    I'm waiting for his quote to change the CU, but I don't believe he's touting for work as he took a month the get to me for this EICR, and he won't be able to change the CU before late March ... he's that busy.
  14. Peterdevon

    Peterdevon Active Member

    I had one last week with a 16th board with no rcd on upstairs lighting and no sup bonding, I solved it by an external rcd next to the consumer unit
  15. Nomenklatura

    Nomenklatura Active Member

    Addressed as in he'll install it at the same time, or addressed as in the new CU will mean it won't be needed?

    He's wrong.
    Peterdevon likes this.
  16. Bazza

    Bazza Screwfix Select

    Agreed wrong. this guy is either
    1. Incompetent and/or
    2. Making work for himself at your expense.
  17. Comlec

    Comlec Screwfix Select

    3. Been watching too many NICEIC webinars during lockdown :)
    Bazza likes this.
  18. rogerk101

    rogerk101 Screwfix Select

    Addressed as in the new CU will provide the RCD or RCBO protection that would turn the absence of visible supplemental bonding in the bathroom from a C2 to a C3.
  19. rogerk101

    rogerk101 Screwfix Select

    Here is a screen shot of his report.
    I think it's over the top, but would appreciate others' opinions.
    Unfortunately the C2 vs C3 in EICRs seem to be based more on opinions than on facts so it's hard to know if he is WRONG or just covering his backside at the expense of a paying customer.
    He is NAPIT registered, but I am pretty sure that if I were to get 10 different NAPIT registered sparks to do EICRs on the same house, no two of them would be the same, and barely any of them would even be similar to others.

    Screenshot 2021-02-20 093509.jpg
  20. The Happy Builder

    The Happy Builder Screwfix Select

    Addressed in, the supplementary bonding may longer be required.

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