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RCD TESTING BS7671:2018+A2:2022

sparkiemike

Anybody notice the changes to 643.7.1 and 643.8 when it comes to RCD testing. In the note it says that "Regardless of the RCD type, effectiveness is deemed to have been verified where an RCD disconnects with in the time stated below with an alternating current test rated at residual operating current I△n"

So the minimum requirement is to set your instrument to RCD type AC and carry out the test even if you have a Type A or Type B RCD.

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  • The 9th Ed of GN3 (2020), Section 2.6.18, says:

    Before using a test instrument, the RCD test button should be pressed. This provides basic information that the RCD is functioning, and will help avoid danger that may occur during test if the RCD did not respond.

    That is a shame. Most meters handle a non-tripping RCD quite gracefully and just time out after a second or so and issue a warning. The internal test resistors inside the RCD do not generally have any protection however, preferring if the contacts are stuck to burn out violently and startle the button pressor with a crack like a small banger of the kind kids used to bring back on the ferry from day trips to France..

    I presume the authors of the GN have not actually done enough testing to encounter that failure mode.. It can be quite unnerving. I'd strongly recommend reversing that in the next edition, and saying why.

    Mike.

  • in reply to mapj1

    Agree Mike, can't see a real world problem here, only lots of theoreticals, a bit like my useless Consultant.

    So, does dropping the previous multitest requirement mean that we should see much cheaper testers enter the market? Every cloud and all that jazz.

  • in reply to mapj1
    mapj1 said:
    I presume the authors of the GN have not actually done enough testing to encounter that failure mode..

    Uncalled for

    mapj1 said:
    That is a shame. Most meters handle a non-tripping RCD quite gracefully and just time out after a second or so and issue a warning.

    As I said, there's no right answer here.

    You failed to respond to "Some devices with RCDs say "Test before use" and the point that you wouldn't introduce a fault current if there were a way to prevent it. Coupled with the fact that the standard for the test instrument is based on standards that BS 7671 is based on (and the RCD product standard) that people are happy to say "only protect some people some of the time" ...

  • in reply to whjohnson
    whjohnson said:
    Agree Mike, can't see a real world problem here, only lots of theoreticals,

    A bit like the need to test RCDs in the first place? And in saying that, I'm not saying that RCDs don't fail (some mcb's do, and I've seen that also) ... but we're cherry-picking risks I think?

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  • in reply to whjohnson
    whjohnson said:
    Agree Mike, can't see a real world problem here, only lots of theoreticals,

    A bit like the need to test RCDs in the first place? And in saying that, I'm not saying that RCDs don't fail (some mcb's do, and I've seen that also) ... but we're cherry-picking risks I think?

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