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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.

Parents

  • Yup - a single a.c. test at IΔn is now sufficient - no 180° test, no 1/2 test, no 5x test., no special tests for RCDs with additional features.

    I suppose it's still one better than just pressing the T button (which was a serious suggestion not so long ago), and still a lot more than the testing we need to do on MCBs.

    I suspect the underlying problem was that the product standards are getting much more complicated - some 30mA RCDs were allowed to need up to 250mA to open within 40ms - and some of the later types have a quite different range of permitted operating times to what we're used to. I gather there were lots of complaints from manufacturers about people returning RCDs as faulty because they failed BS 7671 tests, yet they actually complied with the product standard.

    In terms of risk it doesn't seem too bad. RCDs tend to either work properly or not. If they don't they'll fail the 1x a.c. test. Very few will fail in such a peculiar way that they'll pass the 1x test but fail the others (or the product standard versions of them at least).

       - Andy.

Reply

  • Yup - a single a.c. test at IΔn is now sufficient - no 180° test, no 1/2 test, no 5x test., no special tests for RCDs with additional features.

    I suppose it's still one better than just pressing the T button (which was a serious suggestion not so long ago), and still a lot more than the testing we need to do on MCBs.

    I suspect the underlying problem was that the product standards are getting much more complicated - some 30mA RCDs were allowed to need up to 250mA to open within 40ms - and some of the later types have a quite different range of permitted operating times to what we're used to. I gather there were lots of complaints from manufacturers about people returning RCDs as faulty because they failed BS 7671 tests, yet they actually complied with the product standard.

    In terms of risk it doesn't seem too bad. RCDs tend to either work properly or not. If they don't they'll fail the 1x a.c. test. Very few will fail in such a peculiar way that they'll pass the 1x test but fail the others (or the product standard versions of them at least).

       - Andy.

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