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RCD Failed

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  • 27-05-2020 4:15am
    #1
    adrian92
    Registered Users Posts: 563 ✭✭✭


    I have noticed several times that RCD fails to operate.

    Has anyone else experienced this?


Comments

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    #2
    oscarBravo
    Technology & Internet Moderators Posts: 28,792 Mod ✭✭✭✭oscarBravo


    Moved from Open Source.


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    #3
    [Deleted User]
    Posts: 7,499 ✭✭✭ [Deleted User]


    adrian92 wrote: »
    I have noticed several times that RCD fails to operate.

    Has anyone else experienced this?

    What was the fault ?


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    #4
    adrian92
    Registered Users Posts: 563 ✭✭✭adrian92


    BrownFinger wrote: »
    What was the fault ?

    I just did a crude test. A 20 watt lamp between phase and earth.
    The RCD did not operate.

    I was wondering how reliable RCD is for operating for an earth fault?


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    #5
    oscarBravo
    Technology & Internet Moderators Posts: 28,792 Mod ✭✭✭✭oscarBravo


    Sounds like a faulty RCD.


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    #6
    John.G
    Registered Users Posts: 3,472 ✭✭✭John.G


    Does it trip on the test button?

    Are you using a energy saving bulb which may require < the (max) tripping current of 35ma (8 watts) to trip.


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    #7
    Retro.
    Closed Accounts Posts: 89 ✭✭Retro.


    adrian92 wrote: »
    I just did a crude test. A 20 watt lamp between phase and earth.
    The RCD did not operate.

    I was wondering how reliable RCD is for operating for an earth fault?

    Use the test button

    There was another poster using the test lamp setup, not to be recommended


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    #8
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,536 Mod ✭✭✭✭2011


    Retro. wrote: »
    Use the test button

    Agreed, this is a good preliminarily electrical test. However it should be noted that this electrical test has its limitations. A proper test needs to be carried out using professional test equipment (such as those manufactured by Fluke). These tests should be performed by a competent person. Only then is it possible to determine whether the RCD is performing correctly or not.


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    #9
    John.G
    Registered Users Posts: 3,472 ✭✭✭John.G


    I press the test buttons on my (one) RCD and (one) RCBO a few times/year which I suppose is a reasonable householder functional test.


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    #10
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,536 Mod ✭✭✭✭2011


    +1


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    #11
    Retro.
    Closed Accounts Posts: 89 ✭✭Retro.


    2011 wrote: »
    Agreed, this is a good preliminarily electrical test. However it should be noted that this electrical test has its limitations. A proper test needs to be carried out using professional test equipment (such as those manufactured by Fluke). These tests should be performed by a competent person. Only then is it possible to determine whether the RCD is performing correctly or not.

    Yes and test the RCD with the meter without pressing the test button or switching the rcd

    If it fails testing replace


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    #12
    John.G
    Registered Users Posts: 3,472 ✭✭✭John.G


    Adrian92, in post #1 says "I have noticed several times that RCD fails to operate." post #4 then might indicate that this happened when he did this bulb test but (my) logic then says press the test button and if it then doesn't operate, investigate, surely the test button is there for a reason and I would trust it more than a 20w bulb that draws a unknown load.
    Is there a statutory requirement to test RCDs? (properly) on a timed basis, after initial installation test?


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    #13
    Retro.
    Closed Accounts Posts: 89 ✭✭Retro.


    John.G wrote: »
    Adrian92, in post #1 says "I have noticed several times that RCD fails to operate." post #4 then might indicate that this happened when he did this bulb test but (my) logic then says press the test button and if it then doesn't operate, investigate, surely the test button is there for a reason and I would trust it more than a 20w bulb that draws a unknown load.
    Is there a statutory requirement to test RCDs? (properly) on a timed basis, after initial installation test?

    Don't think so after installation

    The householder should be pressing the test button and their should be signage on the board


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    #14
    awec
    Administrators Posts: 53,438 Admin ✭✭✭✭✭awec


    John.G wrote: »
    I press the test buttons on my (one) RCD and (one) RCBO a few times/year which I suppose is a reasonable householder functional test.

    When testing the RCD in a house, is it just a case of hitting the test button in the fusebox? Should there be any prep done in advance?


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    #15
    John.G
    Registered Users Posts: 3,472 ✭✭✭John.G


    No prep needed, but you might have to reset cooker (timer) clock and a few items like that, suggest carrying out test with most items off like TVs etc, say in the morning or late at night.


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    #16
    Retro.
    Closed Accounts Posts: 89 ✭✭Retro.


    The cooker won't likely be affected

    Put all the electronic appliances on standby before pressing the test button

    If you're using a test meter you're supposed to test first before any resetting


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    #17
    whizbang
    Registered Users Posts: 1,924 ✭✭✭whizbang


    Even a 10Watt bulb at 230v uses over 30mA, and that doesnt allow for cold start current. And LED's and CFL's will still have a significant enough startup current to trip.


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    #18
    John.G
    Registered Users Posts: 3,472 ✭✭✭John.G


    Adrian92 didn't say that he pressed the test button. I had a full neutral to earth fault one time https://www.boards.ie/vbulletin/showthread.php?p=113009132 but before I figured out that this was the problem I made up a plug with a 11K ohm resistor, approx 21 ma, which would trip the RCD almost instantaneously.


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    #19
    adrian92
    Registered Users Posts: 563 ✭✭✭adrian92


    John.G wrote: »
    Adrian92, in post #1 says "I have noticed several times that RCD fails to operate." post #4 then might indicate that this happened when he did this bulb test but (my) logic then says press the test button and if it then doesn't operate, investigate, surely the test button is there for a reason and I would trust it more than a 20w bulb that draws a unknown load.
    Is there a statutory requirement to test RCDs? (properly) on a timed basis, after initial installation test?


    Thanks for the response.
    It is just that I have noticed that RCD fail often to operate in the event of an Earth Fault.

    Wondering if anyone else noticed lack of reliability of RCD?


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    #20
    John.G
    Registered Users Posts: 3,472 ✭✭✭John.G


    My house is "fused", the only way that I would know (RCD fail) is if a fuse blew on a L to E fault, I have got one fairly hefty "tickle" off a live that I stupidly hadn't checked out but it didn't trip the RCD presumably because the current flowing hadn't reached the trip limit as the RCD did trip on the test button.


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    #21
    kramer1
    Closed Accounts Posts: 305 ✭✭kramer1


    Yep, come across dodgy ones all the time, rcbos too


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