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Modifying Ring with no RCD Present on BS3036 CU & MEIWC Question

Joseph Day

Hi all. Second year apprentice still learning the ropes so just a few things to clarify.

I've got a two part question today, but first some context: I've just modified the ring final circuit in my brother's house. There is a ring where the previous house owner had cut into the ring and spurred off a double socket. Something (I think) he's quite entitled to do assuming he only does it the once on the entire ring (although this would be different if he'd spurred from a socket). Anyway, I've since removed that spur and extended the ring into two double sockets, effectively removing the JB for the spur and just having a singular joint extending the new leg into the outgoing leg to the rest of the living room. I hate joints all together, but this was an unavoidable one.

Question time -

  1. Whenever I've been working on a job under my supervisor, to my knowledge he's never issued a MEIWC for alterations to a circuit, including swapping over an RCD (when required e.g. if the function test failed). I was under the impression this was a mandatory requirement. Am I wrong? If it is a mandatory requirement, I plan on issuing said certificate with the approval of my supervisor once it's had a secondary opinion on my test results which I've recorded.
  2. This second question is a bit more problematic. The installation isn't 18th edition which is quite alright, but the CU is BS3036 fuses with no RCD present on any circuit, nor incoming to protect the full board. Now obviously I've modified the circuit, plus being the last man in the board, I'm not sure what the legal requirements are here. I'm hearing mixed sources saying because it's not an 18th edition install, RCDs are not a requirement but because I've altered the circuit, then it is? What's the stance of the community on this one? I've recommended (stressed) that he should upgrade the board, but I don't think he fully grasps the importance of it which is fine as I don't expect him to.

Any advice is appreciated. Thanks all.

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    well there is nothing stopping you having a ring that is all junction boxes and  a spur from each of these per socket. Indeed a similar  arrangement is not that uncommon with houses with a solid floor, so that all the downstairs sockets only have one cable in the back each one being a spur from a ring of sockets upstairs.  It's not an arrangement I like but in practice it gives no problems and saves some cable, and side-steps a cable grouping issue there might be if there were two cables coming down the wall side-by side to keep the ring complete but up and down.

    MW certs are not a legal requirement ,but it is probably an insurance  requirement of work done under an niciec or similar scheme, otherwise who knows what was done and is supposed to be guaranteed. I'd strongly recommend recording the same info whether on an MW cert or not, as when you do a lot of stuff, and a few years later someone tries to blame you for a change that you are pretty sure is not one of your own, then it is a good thing to have some paper - or electronic form- to look back on to say 'ah yes, as you can see we added one socket in the bedroom to existing ring, and here are the Zs and insulation checks we did, - the spur you refer to, that set fire to the loft, is not my work at all.... '

    As regards RCDs, in practice of course the extra risk of one more socket sans RCD is diddly squat, and the building regs requirement is only to not make things worse, so no laws broken. However without an RCD anywhere it does not comply to current regs, so cannot be signed off as a proper 18th edn. compliant install, and anyone doing that under any of the  part P schemes certainly  would not be quite right.

    Cheapest compliant fix is an RCD in a small DIN box in the tails into or out of the fuseboard if you are doing much more than adding a couple of sockets with integral RCDs - RCD sockets are not cheap compared to normal ones

    Longer term a new consumer unit is indeed the preferred.

    But be aware that before the big fuseboard swap, a very thorough check to eliminate any chance there are crossed neutrals, neutral earth shorts etc that fuses alone do not detect. or the first thing after fitting the new board is a call back saying 'it never used to trip like that before you came '....

    There is plenty of 'what have RCDs done for us' literature to show to the unconvinced.

    https://www.ddfire.gov.uk/residual-current-devices-can-save-lives Worth having something like that to help the explanation.

    M.

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  • 0

    well there is nothing stopping you having a ring that is all junction boxes and  a spur from each of these per socket. Indeed a similar  arrangement is not that uncommon with houses with a solid floor, so that all the downstairs sockets only have one cable in the back each one being a spur from a ring of sockets upstairs.  It's not an arrangement I like but in practice it gives no problems and saves some cable, and side-steps a cable grouping issue there might be if there were two cables coming down the wall side-by side to keep the ring complete but up and down.

    MW certs are not a legal requirement ,but it is probably an insurance  requirement of work done under an niciec or similar scheme, otherwise who knows what was done and is supposed to be guaranteed. I'd strongly recommend recording the same info whether on an MW cert or not, as when you do a lot of stuff, and a few years later someone tries to blame you for a change that you are pretty sure is not one of your own, then it is a good thing to have some paper - or electronic form- to look back on to say 'ah yes, as you can see we added one socket in the bedroom to existing ring, and here are the Zs and insulation checks we did, - the spur you refer to, that set fire to the loft, is not my work at all.... '

    As regards RCDs, in practice of course the extra risk of one more socket sans RCD is diddly squat, and the building regs requirement is only to not make things worse, so no laws broken. However without an RCD anywhere it does not comply to current regs, so cannot be signed off as a proper 18th edn. compliant install, and anyone doing that under any of the  part P schemes certainly  would not be quite right.

    Cheapest compliant fix is an RCD in a small DIN box in the tails into or out of the fuseboard if you are doing much more than adding a couple of sockets with integral RCDs - RCD sockets are not cheap compared to normal ones

    Longer term a new consumer unit is indeed the preferred.

    But be aware that before the big fuseboard swap, a very thorough check to eliminate any chance there are crossed neutrals, neutral earth shorts etc that fuses alone do not detect. or the first thing after fitting the new board is a call back saying 'it never used to trip like that before you came '....

    There is plenty of 'what have RCDs done for us' literature to show to the unconvinced.

    https://www.ddfire.gov.uk/residual-current-devices-can-save-lives Worth having something like that to help the explanation.

    M.

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