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upgrade to a dual RCD board (volex)

Discussion in 'Electrics UK' started by HawkEye244, 25 Sep 2020.

  1. EFLImpudence

    EFLImpudence

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    Not to mention the millions of pounds needed to replace RCDs which already cost millions of pounds for negligible benefit.
     
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  3. JohnW2

    JohnW2

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    Quite. Aside from the issue of (the cost-effectiveness of) RCDs in general, I do wish I could find some definitive information about this 'RCD type' issue. The UK is full of Type AC RCDs and, of those here, there seem to be only two people who regard that as a major problem.

    Kind Regards, John
     
  4. EFLImpudence

    EFLImpudence

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    Plus - as you say, you do not have a problem with 'nuisance' tripping, which presumably would be the consequence.
     
  5. JohnW2

    JohnW2

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    Only in relation to flameport's point about "the total leakage on each RCD", which is not related to the 'RCD type' issue.

    As I understand it, flameport's concern regarding the 'RCD type' is that, if loads are connected which do not result in pure sinusoidal AC current, then, far from resulting in "nuisance tripping", his concern that is that RCD functionality might be impaired by those currents to the extent that it doesn't trip when it should.

    Kind Regards, John
     
  6. EFLImpudence

    EFLImpudence

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    Yes.

    Would they then also not trip when tested?
     
  7. AndyPRK

    AndyPRK

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    you need a sequence of events.

    Faulty device producing DC on the mains.
    The test button being pressed on a type AC - No it wouldn't trip.
    Another fault occurring, which would normally trip an AC device.

    Can we keep this post on topic ?
     
  8. JohnW2

    JohnW2

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    Presumably only if the offending "not pure sinusoidal current" loads were connected and drawing current at the time of the test.

    However, as I said in my response to flameport, the problem is the requirement for a 'crystal ball' when sockets circuits are involved - since, even if the RCD trips correctly when tested with certain loads drawing current, it might not when something different is 'plugged in' into the circuit in the future. It seems that his view is that, since one obviously can't know what might be plugged in at some point in time, the only 'safe option' is to never use Type AC RCDs, 'just in case'.

    Kind Regards, John
     
  9. JohnW2

    JohnW2

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    I think it is, given that the OP, who was asking about possible upgrading of his CU, is being told that he should not use one which has type AC RCDs or RCBOs, and that nor should he use a dual-RCD board. Do you believe that is sound, and universally accepted, advice which can/should go unquestioned?

    Kind Regards, John
     
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  11. AndyPRK

    AndyPRK

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    No I don't believe the leakage add up would be a problem.
    The RCBO's this board takes are type A
     
  12. JohnW2

    JohnW2

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    Fair enough, but flameport's point about type AC RCDs/RCBOs appeared to be a general one - do you share his view that such devices should not be installed and, indeed, that where they exist (which must be incredibly common in the UK) they should be given a C3 on an EICR?

    Kind Regards, John
     
  13. AndyPRK

    AndyPRK

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    No they shouldn’t be given a C3

    I have fitted a Type A to my house.
    Though the quality was reduced so I wasn’t inspired to get any more.
     
  14. JohnW2

    JohnW2

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    Fair enough. What about the OP being advised that one should not install type ACs (even if they wouldn't get a C3, other than from flameport and perhaps a few others) - do you think that is appropriate advice?

    Kind Regards, John
     
  15. Taylortwocities

    Taylortwocities

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    Indeed. Any departure from BS7671 could be coded, but the regs doesn't specify the type of RCD that must be fitted for general use, only that it shall be 30mA.
    The only time that a C could be noted (and probably a C2) is if anything other than the correct type of is fitted feeding an EV charge point.
     
  16. JohnW2

    JohnW2

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    The regs don't 'specify the type' explicitly, but they do say that "the appropriate RCD should be selected". However, they also conclude by saying that "For general purposes, Type AC RCDs may be used." - although it's anyone's guess what "general purposes" actually means! Whatever, although I still haven't learned enough about this business, I certainly am not yet convinced that the existence of a Type AC RCD, per se, warrants even a C3.

    Kind Regards, John
     
  17. HawkEye244

    HawkEye244

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    Many thanks to you all
    I appreciate the open dialogue.
    Yes a fair suggestion.
    I'll drop this as an option and continue to try and source affordable RCBOs but as others have suggested to me before they are painfully pricey.
    Maybe I should pay to have the CU upgraded.
    Options
     
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