Splitting supply to two consumer units after meter

Discussion in 'Electricians' Talk' started by Nitch1, Jun 21, 2021.

  1. Tony Goddard

    Tony Goddard Screwfix Select

    Happy, I don't think the "tails" we are looking at here are SWA, the OP says run in conduit, to me it looks like T&E in black PVC conduit, which is almost worse! Although maybe I'm wrong, there a 4 taped earths, has some numbty used SWA and just taped up some armour strands and shoved them in the MET

    OP, what Happay says here is right, it a total dogs dinner, the suppliers fuse cannot be used as protection, you should have 25mm tails out of the isolator into a switched fuse unit adequately fused to protect the outgoing cable - we shouldn't be seeing single insulated wires as we are here.

    The sad, sad thing is that this isn't some bit of carp wiring done back in the day and modified endless times, this is quite new and presumably was done by someone claiming to be an electrician - shocking (pardon the pun)
    Nitch1 likes this.
  2. jonathanc

    jonathanc Screwfix Select

    Apologies. It looked a bit like SWA so it was a guess.

    anyway the back story here would be interesting too. Clearly some issues in the past here!
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  3. The Happy Builder

    The Happy Builder Screwfix Select

    There is mention of cables in walls, so if they are singles in plastic conduit it needs 30 mA RCD protection.

    There appears to be two earths wrapped in tape from each cable which presumably is armour and a conductor?
    Nitch1 likes this.
  4. Nitch1

    Nitch1 New Member

    Well, he's a full picture of the communal electricity cabinet, and also of what it was like when we moved in 5 years ago. It's a house that was extended drastically and converted into two flats during 2015-2016.
    Basically, just before we bought the place, I asked in writing if there were separate meters for each flat, got an answer saying yes.
    After moving in, of course there weren't, and it took a year and a half of dealing with the DNO, council and the supplier (as well as a resisting neighbour) to get separate meters. The was also a successful claim against the developer.
    During the process of separating the meters, had multiple visits from the supplier engineers. Also, a picture of the cabinet was sent to the DNO because they wouldn't create additional MPRNs unless they see that there are phases not in use (originally there was 1 three phases MPRN) and that there's enough room for the meters. I actually had to extend the cabinet itself. Either way, both the DNO and the supplier engineers said nothing about the setup. Nor have two electricians that helped with the process.
    I think the feed to the flats may be on SWAs and not a flexible conduit, was a little confused by the insulation tape at the end.
    The CU on top services the communal areas and smoke detectors in the flats, there are separate CUs in each of the flats.

    IMG_4286.jpg IMG_20170314_185137.jpg
    Last edited: Jun 22, 2021
  5. ElecCEng

    ElecCEng Screwfix Select

    You’re using all 3 phases there, albeit each in single phase configuration.

    Correct way of doing this would be metalclad fused switches instead of those plastic meter isolators, with the SWA (looks like SWA to me) glanded properly into the enclosure. That’s going to cost a fair bit.

    Otherwise you could use plastic switch fuses with tails into a metal adaptable box to gland the SWA into. That’s what you might have to go for as there’s not much on slack on those SWA meter tails.

    Don’t have much of an issue with the SWA itself... Fuses are down rated to 60A and long runs of 16mm in distribution in flats is fairly commonplace. Switch fuses will need to be suitably sized, as will the protection in the CUs. Odds on there being an 80A RCD in them?
    Nitch1 likes this.
  6. Nitch1

    Nitch1 New Member

    Indeed, there are two 80A RCDs in each flat's CU.
    So the SWA looks like 16sqmm to you? The external diameter of the individual wires is a little over 6mm.
  7. ElecCEng

    ElecCEng Screwfix Select

    To be honest this doesn’t look big enough to be anything over 16mm if it’s 4 core...

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  8. Nitch1

    Nitch1 New Member

    Nothing would surprise me, but the question was actually about the SWAs feeding into the flats after the isolators. Do these look like 16mm or 10mm?
  9. The Happy Builder

    The Happy Builder Screwfix Select

    There’s not anything definite to compare them with, the main earth conductors should be 16 mm, but they may be undersized.

    What yo really need is another cupboard to the left of this one to move the SWA cable into and to make space for the fused switches.
  10. Nitch1

    Nitch1 New Member

    Sadly the cupboard was already extended to fit the extra meters, no further extension unless we give us on the foyer window. Will most likely go with adding the fused switches before the CUs, but will see what my electrician has to say now that I have a better understanding thanks to the conversation here.
  11. adgjl

    adgjl Member

    Not quite. As the isolating switches have “eon” written on them, they are the property of the DNO / Meter Operator. Your fused switches need to fit after these, and before your SWA cables to the flats.
  12. ElecCEng

    ElecCEng Screwfix Select

    Clearly with the caveat that the e-on would have to be involved in installing those...

    As has been pointed out earlier e-on should not have connected the SWA in to those isolators. Not clear whether they did, but seeing the SWA they should have advised a better solution.

    Nitch1 likes this.
  13. ElecCEng

    ElecCEng Screwfix Select

    If you look closely at the outer insulation of the SWA is should be embossed with the size.
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  14. Nitch1

    Nitch1 New Member

    Not absolutely sure who did it as it was 3.5 years ago. Most likely EOn just installed these, and later on my electrician connected the SWA to the isolator. There was an in-between stage when both flats were connected to the 100A fused communal phase, just so the DNO can see that two phases aren't connected to anything and issue MPRNs for them. T'was a **** show.

    3X16, thanks for helping with finding the answer for this one!

    So with 16sqmm confirmed, and with the SWA laid in clipped direct method, it can carry up to 94amps. So an 80A fuse should allow me enough power to run the shower and the rest of the house. Will look into doing this instead of adding another CU. Of course, with a switch fuse added first.
    Last edited: Jun 23, 2021
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