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Electricial Fault

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  • 19-04-2010 9:48pm
    #1
    JOHNPT
    Closed Accounts Posts: 517 ✭✭✭


    Can anyone advise me on reason for following fault. An electric shower on its on RCBO trips the ELCB when its on for about 5 mins. What would the reason for this be? It dosent seem to make any sense.


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    #2
    M cebee
    Closed Accounts Posts: 4,431 ✭✭✭M cebee


    it can be 'overcurrent' if the rcbo is undersized but more than likely it's dampness inside the unit

    megger the supply cables and heater tank anyhow as a precaution

    hey do you mean it's tripping a separate rcd?


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    #3
    JOHNPT
    Closed Accounts Posts: 517 ✭✭✭JOHNPT


    Yes its tripping a seperate RCB thats what i cant understand. Usually happens when on for few minutes


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    #4
    M cebee
    Closed Accounts Posts: 4,431 ✭✭✭M cebee


    are they in series


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    #5
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,591 Mod ✭✭✭✭2011


    As Cebee said normally this is due to damp. 99 times out of 100 this us the case.

    Either the insulation resistance on the cable or the shower unit is not high enough. I would guess that it is the latter and the resistance is reduced due to the ingress of moisture.


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    #6
    JOHNPT
    Closed Accounts Posts: 517 ✭✭✭JOHNPT


    No they are not in series. This problem only occured in last 3 wks. It nearly always happens when shower is on after few mins even when nothing else is on in apt. Tenant also noticed that once when he plugged in hover the RCB also triped but this only happened once. Surely if there was a problem with the shower its RCBO would trip. However its the RCB that trips therefore the shower stays on.


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    #7
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,591 Mod ✭✭✭✭2011


    No they are not in series. This problem only occured in last 3 wks. It nearly always happens when shower is on after few mins even when nothing else is on in apt. Tenant also noticed that once when he plugged in hover the RCB also triped but this only happened once. Surely if there was a problem with the shower its RCBO would trip. However its the RCB that trips therefore the shower stays on.
    The shower should have a dedicated RCD.

    So when this RCD trips does the shower still work?


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    #8
    JOHNPT
    Closed Accounts Posts: 517 ✭✭✭JOHNPT


    Yes when RCB trips shower still works. Thats what i cant understand


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    #9
    JOHNPT
    Closed Accounts Posts: 517 ✭✭✭JOHNPT


    The shower is on its own seperate RCBO however this dosent trip its the RCB which controls sockets etc which trips


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    #10
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,591 Mod ✭✭✭✭2011


    So the problem may be unrelated to the shower. I would meggar all circuits going through the socket RCD. As you said another appliance was causing the RCD to trip. It may be a faulty appliance that is on a socket circuit.

    It may also be something that you switch on when the shower is on like a bathroom heater.

    Split the socket circuits up over 2 RCDs and work it out by a process of elimination.


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    #11
    JOHNPT
    Closed Accounts Posts: 517 ✭✭✭JOHNPT


    Thanks for advice. It may not be related to shower however it always occurs when shower is on after about 5 mins which is kinda strange. Nothing else on in apt only shower and it still trips


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    #12
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,591 Mod ✭✭✭✭2011


    Sometimes the best way to sort these things is by a process of elimination. I bet that if you have 1/2 the sockets on one RCD and 1/2 on another then only 1 RCD will trip. You will then be 50% closer to finding your problem. Then when you know which 1/2 of the sockets is causing the problem transfer a few more circuits to the "good" RCD until you have it down to 1 circuit. Then chevy each point on the circuit.

    Perhaps there us a bathroom fan on that circuit that you are unaware of??


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    #13
    JOHNPT
    Closed Accounts Posts: 517 ✭✭✭JOHNPT


    I dont think there is a bathroom fan but i will check. Thanks very much for all the advice


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    #14
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,591 Mod ✭✭✭✭2011


    I dont think there is a bathroom fan but i will check. Thanks very much for all the advice
    maybe not a fan, I was just giving an example of something being through the socket RCD that you may not expect. You never know what someone else may have done!!

    Good luck with it.


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    #15
    M cebee
    Closed Accounts Posts: 4,431 ✭✭✭M cebee


    ya haven't come across this 'phenomenon' with showers

    i would megger outgoing side of rcd (L-E,N-E) with appliances out as 2011 said

    and test it as well


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    #16
    Randyleprechaun
    Registered Users Posts: 876 ✭✭✭Randyleprechaun


    I saw something like this about 7 or 8 years ago while helping another guy wiring a house. After ESB was hooked up, an RCD or RCBO was tripping when an unrelated item was tuened on. i can't remember the specifics now but it was simillar.

    Anyway after alot of head scratching, we bit the bullet and started to screw off all(and I mean all!!!!) the accessories. Eventually we found a neutral trapped under a 3,5 screw. i can't remember whether the neutral was on the circuit being switched on or on a circuit on the tripping device.

    Long story short, I'd go looking for a minor fault like that. It may sound like a tedious job, but it took us about 2 hours and that was in a 5 bed two storey house. From your post it appears you are working in an apt, so shouldn't take too long.

    It may save alot of "head scratching" or worse!!!!!!!!!!!!


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