RCD Nuisance Tripping

Discussion in 'Electricians' Talk' started by JohnJohn, Nov 10, 2003.

  1. JohnJohn

    JohnJohn Member

    I had been experienceing nuisance tripping at about 6:07 pm each evening, and having eliminated time clocks, boiler switching etc put this down to a power surge when Southern electric switch supplies. Anyway eventually found by Isolating both the Washing M/C and Dishwasher the problem dissapeared. Just switching off on their front panels is not enough they have to be swicthed off at the wall socket or isolator above the worktop. I then found that if I repeatedly switched them on and off quickly at the wall (still with the applianc front panel switched off) on about the third time the RCD (30ma) would trip. I have now fitted a split load consumer unit and put the kitchen on the non RCD side but still wonder what the underlying problem was, maybe the old RCD was over sensitive or there maybe suppressors fitted in the appliances prior to their front panel switches. Both the washing M/C and Dishwasher are under 2years old and either one caused the problem so I can't believe they are at fault. Any clues ??
     
  2. Dr Who

    Dr Who New Member

    John,

    I would strongly suggest you find the root cause of the problem rather than the solution you have posed. Remember that RCD's are there for your, and others, safety and it tripping out is a sign that it may be doing the job that it was designed to do!

    Although your appliances are relatively new they could still be the cause of the problem. As they both involve water you could have a slight leak somewhere which is causing the fault leakage current to earth.

    Have you tried the following :

    1. Unplugging the appliances from the wall but leaving the 'isolation' switches turned on. (to check that water is not getting into the socket if placed under a worktop say near a sink)

    2. Unplugging the dishwasher, leaving the washing machine plugged in

    3. Unplugging the washing machine, leaving the dishwasher plugged in.

    DR Who

    P.S. Remember - Safety first!
     
  3. Dr Who

    Dr Who New Member

    PS I know that I say I am a doctor but I don't do mouth to mouth resuscitation or heart massage in the event of an electric shock! Unless your name is Cat Deely or other delectable female!
     
  4. Dr Who

    Dr Who New Member

    Sorry, youve already done steps 2 and 3. Must learn to read properly!
     
  5. JohnJohn

    JohnJohn Member

    Thanks doc, I agree the underlying cause is important
    and I haven't done this as a permanent solution.

    I had to replace the old fuse box style consumer unit any way so it was easier to do that than change the old RCD.

    I had tried each appliance on its own and either one gave the problem. The dishwaher came from my old house and I never had nuisance tripping there but the RCD was 100ma. I had replaced /checked the wiring & switches in the kitchen and even replaced the appliance sockets but no difference
    Each appliance worked OK and never tripped when running only when being switched on/off quickly (or a power surge!.

    Having replaced the consumer unit, I will now try running them off the RCD (also 30ma) side and see if the problem returns, if is doesnt then I guess it was a duff RCD.

    Both are cold fill and I notice there is no earth bonding on the supply pipe at that point (there is elsewhere) so I will also do that.

    Probbably a red herring this but when wiring in the new cu I had to replace a kitchen spur cable which was too short, this fed one socket and from there fed a fused spur for the gas hob ignition. I quickly removed the socket and pulled through the new supply cable leaving the other cable (to the hob) in place, but when I came to reconnect the socket the existing wires (to the hob) were in the wrong position with N & E swapped relative to the socket connections (cant be 100% certain they hadnt moved but I had to physically repositiuon N & E to be correctly lined up)
    That socket only supplies a rechargable vaccume but surly that would have continually tripped the RCD?
     
  6. oilly brother

    oilly brother New Member

    Hi

    I had similar experiences with an RCD, eventually cured by replacement with a newer version that was nuisance trip resistant ( Hager brand)

    We have an old power amplifier that has a noisy mains transformer, we could replace it , but the 50Hz buzz does not warent £100+ to replace it, at the time of the RCD problem this buzz started to change, in the evenings/night it started to make all sorts of chattering noises as well, I suspected this is something to do with the telemetry signals that are superimposed on the power lines for control purposes, the chattering noise was abated by fitting a power line filter, but could it have been the cause of the RCD problem as well.

    Anyone else had similar experiences ?
     
  7. supersparky

    supersparky New Member

    just thaught td throw the spanner in the works, if your kitchen is on the ground floor and has an openable window or door, it is very likely that the sockets will be 'resonably expected to supply equipment for use out doors' then by regs the sockets must be on the rcd side.

    BR
     
  8. JohnJohn

    JohnJohn Member

    Having spoken to the Mrs she said that the rechargable vacuum hadn't been charging properly, but now the new cu is in it's working fine. This backs up my suspicion that socket had been wired incorrectly, although I still cant believe it didn't permanently trip . So anyway I will be putting the Kitchen back onto the RCD and see how it performs.
     

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