Tripping RCD's

Discussion in 'Electricians' Talk' started by Pikerray, Apr 30, 2009.

  1. Pikerray

    Pikerray Member

    I have a seperate RCD consumer unit in the Log Cabin and the supply for it comes from a split load board with RCD as well from the house, the problem is that the RCD keeps tripping at the house end so

    Are both RCD's conflicting with each other ?

    My other Log cabin has only a main switch consumer unit and this has no problems at all.
  2. CraigMcK

    CraigMcK Screwfix Select

    If your asking if both RCD's are adversly effecting each other then no their not.

    2 RCD's of the same trip rating in series is never a good idea, because you can't guarantee discrimination between them. But it's strange that it "keeps tripping" this suggests that you do have an earth leakage in the system. One possibility is that it's a cable fault somewhere between the house and the cabin, that would explain why the cabin one is not tripping.

    Changing the cabin one to a switch would not solve the problem, and the house RCD will continue to trip. I would suggest you get someone in to check the wiring. But in the mean time, unplug everything in the cabin and see if it stops, then you will know if it's a system or appliance fault.
  3. Sounds like the cabin is contributing to leakage already in your home..

    Isolate the cabin circuit and check IR, if possible.

    But wouldn't the cabin be best supplied on the non RCD side if it has RCD protection?

  4. Pikerray

    Pikerray Member

    The armoured cable is only about 6 month's old and I know it is not damaged in anyway.
  5. JP.

    JP. Screwfix Select

    Morning Reg..ows things going M8..:)
  6. JP.

    JP. Screwfix Select

    Must say agree with no RCD protection at house position Reg..SWA sub and all that M8..:)
  7. Morning Reg..ows things going M8..:)

    Hi JP...


  8. General Factotum

    General Factotum New Member

    What load do you have in the cabin? If you have several PCs, their switched mode power supplies may cause enough leakage to trip a 30mA RCD. A typical PC PSU leaks about 3-5mA to earth.
  9. Pikerray

    Pikerray Member

    Not much load at all really, just a lawnmower on charge and a couple of batteries, apart from that nothing else.
  10. Rossi29

    Rossi29 New Member

    How many circuits are protected by the RCD that keeps tripping? The fault may be nothing to do with the cabin.
  11. Pikerray

    Pikerray Member

    The circuit at the house end is a dedicated one, it just supplies the log cabin which then enters the CU which has 4 ways, 1 x for lighting, 1 x for power and the other 2 are blank.

    The RCD at the house end and the log cabin end are both 32amp.
  12. Rossi29

    Rossi29 New Member

    can you clarify your arrangement? Is the RCD that keeps tripping a main switch on the split load board? If yes then 32Amp dosen't sound right to me. Or is it an RCBO or MCB that keeps tripping?
  13. Pikerray

    Pikerray Member

    MCB that keeps tripping.
  14. Rossi29

    Rossi29 New Member

    OK if its the MCB then you either have an overload or a short circuit somewhere, unless the MCB is not working correctly. MCB's work differently to RCD's. If you are competent then I would suggest changing the MCB with your other one at the same rating to see if this makes any difference.

    The other thing you need to ask yourself is; are you using the correct rated MCB? Your 32amp MCB is protecting the cable running to your log cabin. What size is this cable? and do you know how many amps you are using in your log cabin?

    Other than this, it must be a fault with you armoured cable. Do an installation resistance test on the armoured and see what this shows.

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