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RCD tripping...

Tomgunn
Last Friday, (the 4th). Worked hard on house... stopped at gone 7pm, shower, cook, eat by 8.30pm. DING DONG!!!


Duh, answer door and next door neighbour... "my kitchen lights, and other things, all gone out!!"


Checked out the CCU in his kitchen and narrowed it down to the SWA feeding the garage!


Went to garage, chest freezer... could it be that simple? NO!


Noticed a 32amp fuse. Mmmmm? Only socket was a foot under the CCU. Wrong fuse for a 'radial?' Never mind.... keep checking.


Switch CCU off, RCD stays in! Switch CCU on, RCD trips! 9pm now!!!


Took a long extension lead from my garage to his.


Saturday morning, grabbed some tools and a tester... met by him, "it's ok, I'm with British Gas and they are now coming out!" WHY didn't he tell me beforehand????


British Gas man turns up. I told him there wasn't a problem with the freezer... didn't believe me.


Side of the British Gas van read... "Looking After Your World" / similar.


(Trying hard to keep this as short as poss!!).


Garage CCU is an old, (but modern looking), 404 Wylex. 


Tell's neighbour... "it's your CCU!!"


I butted in saying... "I doubt it!"


"Oh yes it is"


"Oh no it isn't!!"


He tell's neighbour, "I'm going on my holidays for this week... then when I return I have a weeks lot of works ahead so, I'll see you in two weeks' time and I'll replace the CCU for you then!" 


British Gas van... "Looking After Your World" haha!!


I asked... "have you checked the gland as I don't think it'll be the CCU?" He said he didn't have the time!!


I said... "you know that RCD's, (now... if anyone is going to pull me up on this then I got this info, about the RCDs' from this forum!!), have a 6% failure rating?"


He replied... "what does that mean?"


Off he went leaving my neighbour running a 40ft long extension lead, from his bungalow to his garage for, TWO weeks'!!


NOW, how many have had this type of problem with a 4 way CCU??? I turned it off and left, the night before BUT, my neighbour told me that the lights went out again, when I'd turned the CCU OFF! I just cannot believe that the problem is with the CCU. The British Gas man disconnected everything inside the CCU. 


He also told me that the garage had a 'ring main' and I said it didn't but some fool had fitted a 32amp fuse to a radial BUT, it turns out the DSO, a foot beneath the CCU was wired as a ring circuit! My guess is.., (and I remember some 30 years' ago this being fitted), the chap who fitted the CCU only had a 32amp fuse with him so he made this DSO a, haha, RING! 


So, any ideas or have you come across this before?


I'm chomping at my bit to see what's wrong but I cannot do this now, damn!


Either way, good luck everyone, hope all's going well!


regards... Tom











  • 0
    Very hard to imagine a fault in a CCU that still occurs with the main switch off, that is not obvious to the trained eye with the lid off. Assuming there is no dead mouse in the CU, or obvious scuffing of the cores as they leave the gland, my money would be on damage to the SWA, perhaps a puncture of the outer plastic and then water ingress.

    A meter will reveal all - perhaps the gas man has one..

    Let's hope the CU repalcement will be covered by the British Gas policy, and is not charged at full rate, as it may well not be the end of it.
  • 0
    I am with Mike in suspecting the SWA, while I have found a few faulty RCDs they had failed completely rather than becoming too sensitive. You have two weeks to do the testing to find the cause or you can let the BG man change the CCU and then be confused why it has not resolved the problem?.  But why BG would find it acceptable to let the problem  continue for two weeks while their man is on holiday would be of concern to me if I had a contract with them. 


    I found a sensitive mA clamp meter to be essential when tracing RCD issues but mine has started giving spurious readings so I have to resort to dead testing on the very odd occasion I get involved these days. ?
  • 0
    Hi, I don't know if his cover, with BG, allows for a new CCU change? 


    I turned it all off, Friday night, and then the bungalow lights went out, after I left but - they have been ok since the sparks disconnected everything from the CCU.


    It would have taken him 10 minutes to check the switch... I know the previous owners, about a year ago, had a sparks working in there, and the bungalow too.


    Haha, I'm really gagging to check it out, as I mentioned, grrrrrrrr!!!!


    My son went away, for a week last year, and his neighbour phoned him to say he could hear a 'pissing' sound, as they have an alley between them, so my son had his friend turn off the water from the road... came back and a mouse had chewed through the cold supply to the washing machine!


    Oh well... good luck!
  • 0
    kfh:

    I am with Mike in suspecting the SWA, while I have found a few faulty RCDs they had failed completely rather than becoming too sensitive. You have two weeks to do the testing to find the cause or you can let the BG man change the CCU and then be confused why it has not resolved the problem?.  But why BG would find it acceptable to let the problem  continue for two weeks while their man is on holiday would be of concern to me if I had a contract with them. 


    I found a sensitive mA clamp meter to be essential when tracing RCD issues but mine has started giving spurious readings so I have to resort to dead testing on the very odd occasion I get involved these days. ?

     


    Sorry to hear about your clamp meter!! I have one for earth leakage too BUT... it was gone 9pm and then when I went there, the next day, his daughter said I should leave it alone... I said something sarcastic and left!


    I'm with you two too, about the SWA... but, I wondered about the gland as well? It can only be a simple fault and, like you, you shouldn't leave a customer with a 40ft lead from your house to the garage where cars are driven over it / rain / snow... well no snow yet! ?


  • 0
    ? " Off he went leaving my neighbour running a 40ft long extension lead, from his bungalow to his garage for, TWO weeks'!!"

    Usually Gas fitters are much more diligent than that. I suspect that he was trying to upset you Tom.

    If they are not happy with you continuing with the work, make sure you tell your neighbour the possible consequences

    Legh

  • 0
    Legh Richardson:

    ? " Off he went leaving my neighbour running a 40ft long extension lead, from his bungalow to his garage for, TWO weeks'!!"

    Usually Gas fitters are much more diligent than that. I suspect that he was trying to upset you Tom.

    If they are not happy with you continuing with the work, make sure you tell your neighbour the possible consequences

    Legh

     


    Hi Legh... what are you saying, haha... British Gas torture against superior electricians'?


    Tell ya wot... I just want to sort it out BUT, (as poor old Peter Green would've said... RIP ?), "Oh Well Prt 1."


    Cheers...


  • Former Community Member
    0 Former Community Member
    Just let British Gas go ahead and change the CU. Smile at your neighbour and say you're glad he was able to get it sorted. All of this is second guessing. Without separating the circuits and IR testing individually, it is impossible to pinpoint the culprit in the installation. We all tend to have a fear (reluctance at least) of doing IR tests, but it really is dead easy and only takes about 30mins.

    Pop your head in in a few weeks to make sure that EVERY circuit is covered by an RCD.
  • 0
    SKElectrical:

    Pop your head in in a few weeks to make sure that EVERY circuit is covered by an RCD. 


    Well hang on! Why does this distribution circuit have to be RCD protected? ?


  • 0
    Chris Pearson:
    SKElectrical:

    Pop your head in in a few weeks to make sure that EVERY circuit is covered by an RCD. 


    Well hang on! Why does this distribution circuit have to be RCD protected? ?




    I would have thought that the SWA, to the garage, would need to be RCD protected?


    I have also been confused as to the need, or not, to TT an SWA run, in the garden etc, (exporting the PME earth), but that only requires being TT'd under certain conditions SO...  not essential for an RCD in this case??


    regards...


  • Former Community Member
    0 Former Community Member
    Domestically, why wouldn't you RCD protect each circuit? The refs will no doubt ask of this within a couple of years anyway. I only fit RCBO CUs so the nuisance tripping /resetting is not an issue.

    By all means supply the garage CU via an MCB, but do check the N-E IR reading :-)

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