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ELCB or RCD tripping

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  • 29-11-2016 5:41pm
    #1
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 19,759 Mod ✭✭✭✭


    My ELCB is tripping for no apparent reason.

    Over the past few weeks, my ELCB has tripped about 4 times during the night at between 2am and 4am (different time each night). Electrical consumption at night time is of the order of 100w at that time.

    It does not trip during the day at all. No changes to electrical equipment has been made over this time.

    The only suspects I have are the ELCB unit itself, and perhaps the fridge/freezer.

    When restored, there is no re-tripping so whatever caused it has gone. The thought occurred to me that it could be the fridge compressor turning off and causing an induced earth current, but I have no way of checking this.

    Any ideas?


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    #2
    Gashmuncher
    Registered Users Posts: 62 ✭✭Gashmuncher


    The problem you are having can be very difficult to trace. It's an intermittent problem and has disappeared at the time you reset the device. Normally the tripping becomes more frequent over time and eventually it becomes clear what is causing it. You need to get the RCD tested or replaced to rule out a faulty device. It would also be worth putting the fridge circuit on a separate RCBO. If the fridge is causing the problem, only this RCBO will trip. This will be easy if you can identify the fridge circuit neutral. Best of luck


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    #3
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,595 Mod ✭✭✭✭2011


    Sam Russell wrote: »
    My ELCB is tripping for no apparent reason.

    Over the past few weeks, my ELCB has tripped about 4 times during the night at between 2am and 4am (different time each night). Electrical consumption at night time is of the order of 100w at that time.

    It does not trip during the day at all. No changes to electrical equipment has been made over this time.

    The only suspects I have are the ELCB unit itself, and perhaps the fridge/freezer.

    When restored, there is no re-tripping so whatever caused it has gone. The thought occurred to me that it could be the fridge compressor turning off and causing an induced earth current, but I have no way of checking this.

    Any ideas?

    Intermittent problems are always the hardest to pinpoint. Sometimes they are due to moisture and sometimes they are due to a combination on events coinciding. If I was the electrician trying to fix this I would consider:

    1) Carrying out an insulation resistance test on the wiring to see if there was an issue with the installation.

    2) Test the RCD to ensure that this device is not faulty.

    3) If possible / practical tests the portable / plugged in appliances.

    4) If none of the above highlighted an issue then I would install an RCBO per circuit. Depending on how many circuits this may be very expensive so failing that I would install RCBO's on the circuit(s) that I feel are most likely to have an issue. Following this the problem may not reoccur. If the issue persists at least it will easier to pinpoint it and only some sockets will be impacted.


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    #4
    meercat
    Registered Users Posts: 4,745 ✭✭✭meercat


    my first instinct with an rcd trip would always be the immersion.make sure its turned off


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    #5
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 19,759 Mod ✭✭✭✭Sam Russell


    meercat wrote: »
    my first instinct with an rcd trip would always be the immersion.make sure its turned off

    Thanks for your comment - and the others.

    I do not have an immersion - or at least it has never been turned on.

    For historical reasons (that no longer apply), I have two ELCBs side by side on the board and the house sockets are divided into two zones. No MCBs have tripped. The one tripping has the kitchen, CH, Fridge, garage, and bedrooms. At the time of the trips, only the fridge is 'active' and other background consumption is about 100 w.

    If it is the fridge, I could put it on and extension onto the other ELCB. For such a rare event, it is a pita but I might try it next time.

    If it is a temperature based fault (it was very cold when it tripped) I might look at the garage circuit. That is a bit complicated because it includes some protected circuits for the sockets and some lighting circuits. I think I might isolate that circuit next.

    Changing the actual ELCB itself is a major job, but what I might think of is to wire both through the one that has not tripped.


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    #6
    brightspark
    Registered Users Posts: 2,637 ✭✭✭brightspark


    Mice eating the cables?


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    #7
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Sam Russell wrote: »

    Changing the actual ELCB itself is a major job, but what I might think of is to wire both through the one that has not tripped.
    Putting all circuits into one RCD can make it trip where having two might not, as cumulative leakage can add up with more circuits on a single RCD.

    Having 2 RCDs is a help, as it helps point in the right direction.
    Rather than put all circuits through the non tripping one, try swap them around.


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    #8
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 19,759 Mod ✭✭✭✭Sam Russell


    brightspark wrote: »
    Mice eating the cables?

    I do not think so.
    Bruthal wrote: »
    Putting all circuits into one RCD can make it trip where having two might not, as cumulative leakage can add up with more circuits on a single RCD.

    Having 2 RCDs is a help, as it helps point in the right direction.
    Rather than put all circuits through the non tripping one, try swap them around.

    Good point.

    Why does it trip when demand is so low but not during high demand? The only condition that applies is low temperature. The total load current is less than 500 ma divided between the two ELCBs. No trip when load current is over 20 amps. Strange.


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    #9
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Sam Russell wrote: »
    I do not think so.



    Good point.

    Why does it trip when demand is so low but not during high demand? The only condition that applies is low temperature. The total load current is less than 500 ma divided between the two ELCBs. No trip when load current is over 20 amps. Strange.
    High loads usually have more of a bearing when it's neutral earth faults, not forgetting that an actual faulty circuit coming on will be independent of any load or demand if it's the live that's faulting to earth.

    One or two things that are more active at night is mice etc and condensation. Outdoor sockets or lights that are on an rcd can be more damp at night.


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    #10
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 19,759 Mod ✭✭✭✭Sam Russell


    Bruthal wrote: »
    High loads usually have more of a bearing when it's neutral earth faults, not forgetting that an actual faulty circuit coming on will be independent of any load or demand if it's the live that's faulting to earth.

    One or two things that are more active at night is mice etc and condensation. Outdoor sockets or lights that are on an rcd can be more damp at night.

    That all makes sense.

    I think I will start with the garage circuit as that looks like the most likely culprit.

    Thanks for the answers.


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