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Safe way to cap off unused supply?

Discussion in 'Electrics UK' started by angularbanjo, 3 Jul 2017.

  1. angularbanjo

    angularbanjo

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    Hi

    Doing up the kitchen at the moment and there is an old unused socket above the sink that must have been for an extractor fan (long gone).

    Its still wired (i assume live) with live/neutral/earth going into the connectors.

    I've got a nice shiny copper blanking plate which I'll fix over the mounting box so it's obvious for future generations that there's something in there. So once I've killed the power to the whole house from the fusebox, what's the best way to cap off the wires (I'd rather do something a bit neater and more permanent that just use electrical tape).

    Thanks in advance
     
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  3. Adam_151

    Adam_151

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    Use connector block http://www.screwfix.com/c/electrical-lighting/terminal-strips-blocks/cat830486

    behind the blank plate. If its metal box behind, then connect the earth to the terminal on the box

    Edit: Just seen the blanking plate is copper, that must be earthed along with the box, so you need a short piece of earth to link the two and then put your earth from teh cable in there with it
     
  4. sparkwright

    sparkwright

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    If you are doing up the kitchen, maybe you are able to damage the walls and then make good.

    If so, you MAY be able to trace the wiring, and pull some out. You then may be able to terminate the cables in a junction box somewhere fairly hidden, such as in a kitchen cupboard, ceiling void, under a floorboard etc.
     
  5. stillp

    stillp

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    Can't you disconnect the cable from its source?
     
  6. JohnW2

    JohnW2

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    That's obviously the best approach. However, given that the OP is not even sure that the cable is still live (he is just 'assuming' that is), I would suspect that he probably has no idea where it comes from.

    Kind Regards, John
     
  7. stillp

    stillp

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    In that case he should try to find out!
     
  8. JohnW2

    JohnW2

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    Ideally he should - and he certainly ought to start by determining for certain whether or not it is live!

    As for finding the source, that could possibly be easier said than done, without tearing his house to pieces. I have at least a couple of them (live ones) here. I was obviously able to ascertain what circuit they were powered from, but I gave up trying to determine where they were connected to the circuit, so ended up just 'capping them off', like the OP!

    Kind Regards, John
     
  9. ban-all-sheds

    ban-all-sheds

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    "For certain" is a problem.

    Determining that it is live, for certain, is easy. But if it's dead when tested, then the only "for certain" way to determine that it will never become live is to find the source of it.
     
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  11. ban-all-sheds

    ban-all-sheds

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    And I have to ask:

    Why copper?

    Will you be using a gasket to avoid direct copper to galvanised steel contact?
     
  12. JohnW2

    JohnW2

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    I agree. However, the OP believes ('assumes') the cable to be live - in which case, as you say, confirming that with certainty would be no problem.

    It is obviously true (in any 'testing for dead' situation) that one cannot ever be certain that any cable could never become live unless one exposes the entire length of the cable, which will very often be totally impractical. Contrary to what you suggest, merely finding (and disconnecting) the (current) source cannot demonstrate "for certain" that it could never become live again, because there could be potential cross-connections along the part of the cable that you have not visualised.

    Kind Regards, John
     
  13. JohnW2

    JohnW2

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    I'm not sure that I have ever seen a solid copper blanking plate- have you? What I have seen are steel blanking plates with copper plating just on the outer surface.

    Whilst I think that solid copper ones are either rare or non-existent, solid brass are common, and they do come with gaskets. If copper ones do exist, I imagine that the same is probably true of them.

    Kind Regards, John
     
  14. angularbanjo

    angularbanjo

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    Thanks for all the helpful replies.

    The 'copper' blanking plate is in fact brass but with a copper colour finish. There is a clear plastic gasket with it. "why copper?". Well, we're going for copper recessed lights, copper plug sockets and switches, copper kettle etc as a colour scheme to go with the grey/neutral kitchen.

    As for whether the cable is live or not, I'm obviously not an electrician otherwise I wouldn't be posting on here so it seems to me the safest thing to do is to assume that it is, then make safe. I'll switch the power off at the mains then fit the 3 wires (L/N/E) into a single connector block as per Adam 151's suggestion then fit the blanking plate. I'm not going to try to find the source of the cable as the kitchen's pretty much finished.

    Is there anything inherently unsafe about that idea?

    Thanks
     
  15. EFLImpudence

    EFLImpudence

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    Adam did not and would not say that. You would soon know if it became live by doing that.

    He said connect the Earth wire to the back box if it is metal.
    Put the L and N (and E if back box plastic) in separate connector blocks.
     
  16. angularbanjo

    angularbanjo

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    Thanks, got it. 2 separate connector blocks for Live and neutral then earth into the back box which is indeed metal. Thanks for the quick reply and apologies to Adam who I misinterpreted.

    Ironic that you're posting from Portugal, the only place we've ever had problems with electric shocks. Once in a villa with a light switch above our bed that threw my wife across the room when she switched it on. Then again in the same villa where the washing machine gave her a nasty shock. She lost power in her right arm and ended up swimming round in circles for the rest of the holiday as a result! Apart from that and witnessing a fatal car smash on the N11 it was a great holiday (Lagos/Praia de Luz)
     
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  17. EFLImpudence

    EFLImpudence

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