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RCD testing question

Marc Lambert

Hi

Just reading GN 3 page 95, operation of RCDs.

I've always thought, (and taught) that you press the test button at the end of the sequence of RCD tests simply because if you you use the test button first you can "unstick" a potentially faulty device and allow it to pass the tests when it might not have?

At a recent CEF / NICEIC Techtalk event they said exactly the same thing, "Join CEF's (or NICEIC) Head of Technical Solutions Darren Staniforth and electrical legend Dave Austin for a TechTalk near you."

Any thoughts on what page 95 GN3 says now? That you press the test button before using the tester?

Kind regards

Marc

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  • 0

    I think the reason these devices get stuck is because nobody reads the rcd instructions attached  to the front of the consumer units which makes clear that the RCD test button  should be pressed periodically. Used to be quarterly, now, I suspect, its whatever the manufacturers recommend.

    Is it wise, therefore, to place the responsiblity for the major method of domestic earth fault protection in the hands of electrically non-competent householders?

  • 0 in reply to Legh Richardson
    Legh Richardson said:
    I think the reason these devices get stuck is because nobody reads the rcd instructions attached  to the front of the consumer units which makes clear that the RCD test button  should be pressed periodically.

    I have to confess that I wasn't aware of the need to press the test button until I did my training. In fact, I wasn't really aware that I had RCBOs in my outdoor (under cover, but otherwise exposed) CU. The test buttons had not been pressed for at least 21 years! As a result, when I came to press them, one did nothing and after I opened it manually, it refused to re-latch.

    I suspect that the reason for pressing the test button at the end is a combination of doing what you were taught (monkey see, monkey do) and the fact that (reading left to right as you do) it is the last column in the Schedule of Test Results which is for the test button.

    Having thought about it, I think press the button first. If it trips, then you have at least proved that the mechanism is sound.

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  • 0 in reply to Legh Richardson
    Legh Richardson said:
    I think the reason these devices get stuck is because nobody reads the rcd instructions attached  to the front of the consumer units which makes clear that the RCD test button  should be pressed periodically.

    I have to confess that I wasn't aware of the need to press the test button until I did my training. In fact, I wasn't really aware that I had RCBOs in my outdoor (under cover, but otherwise exposed) CU. The test buttons had not been pressed for at least 21 years! As a result, when I came to press them, one did nothing and after I opened it manually, it refused to re-latch.

    I suspect that the reason for pressing the test button at the end is a combination of doing what you were taught (monkey see, monkey do) and the fact that (reading left to right as you do) it is the last column in the Schedule of Test Results which is for the test button.

    Having thought about it, I think press the button first. If it trips, then you have at least proved that the mechanism is sound.

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