Sensitive Legrand Rcd

Discussion in 'Electricians' Talk' started by Clarky94, Mar 20, 2019.

  1. Clarky94

    Clarky94 New Member

    I moved into my current house 2 years ago, every now and then we get was i call a power blip where the power goes off and on in a split second which is sufficient to trip the RCD - i usually have to switch the electric off reset the rcd and then turn all the power back on - this is a right royal pain as the fusebox is located in the garage and the only access is via the up and over door. The lights stay on as they are on the none protected side of my legrand fuse box.

    I live in a close of 6 house and these power blips only seem to trip mine and my neighbour opposites RCD any suggestions. The only similarity is both the fuse boxes are the same - mine is fully populated

    I am also considering the installation of an electric garage door would i be ok wiring this door into the none RCD protected side of the fuse box even i installed an RCD protected Spur socket - what i dont want to do is wind the door up manually just to reset the RCD - also disconnecting the power for a long time can reset the auto garage door.
     
  2. rogerk101

    rogerk101 Well-Known Member

    You may have a device in your house that is generating voltage/current spikes which are causing the RCD to trip. (I know because I once tried using a 'digital' smart pump for my underfloor central heating system, and it was causing my RCD to trip. I changed the pump to a good old Grundfoss one and all has been fine ever since.)
    If you can identify what it is that's causing the trips, then you could consider changing it (like I did with my pump). Alternatively, if you can't find the culprit, you could try using a C type RCD (you've probably got a B type one). Most electrical suppliers like TLC would let you buy a C type and return it within 30 days if it is still in as-new condition.
     
  3. Clarky94

    Clarky94 New Member

    i am pretty sure its not something in my house if mine trips the house opposite also does usuallly confirmed by a wave from them as they go into the garage to reset the RCD - not sure what a type c rcd is - if changing this sorts it even better - we can do for months without anything - i usually phone up the electric company when it happens and its always a fault their end - birds nest on transformer was the last one
     
  4. Comlec

    Comlec Well-Known Member

    Think you might be confusing RCD and MCB types.
    MCBs come in type C but RCDs do not.

    For a explanation of RCD types you could look here
     
  5. Clarky94

    Clarky94 New Member

    UNADJUSTEDNONRAW_mini_15c0.jpg This the fuse box i am referring to the problem RCD is in the middle
     
  6. Pollowick

    Pollowick Well-Known Member


    You and one neighbour ... out of 6 houses. There is probably a 3 phase supply coming in and each phase supplies two houses. So it points to something elsewhere on that phase rather than in your house. It would be difficult to confirm if it is the case without measuring house to house voltages - something I would suggest in NOT to be done.
     
  7. Clarky94

    Clarky94 New Member

    Sounds like a something to check out- but trying to get the electric company to take responsibility is going to be a challenge
     
  8. Bazza-spark

    Bazza-spark Well-Known Member

    You could remove the RCD and replace the protected MCB's with RCBO's. That may cure your problem, or resolve it to 1 circuit only, and would also gain you spare ways.

    Kind regards
     
    Philip Hyde likes this.
  9. Clarky94

    Clarky94 New Member

    Replacing all the MCB’s with RCBO’s might be an expensive option maybe a different RCD might be more cost effective option,
    I did contact the electric company all the did was pass the buck.

    Was thinking of adding a single outlet from the cooker rcd and having a dedicated rcd protected spur if that’s allowed
     
  10. Philip Hyde

    Philip Hyde Member

    Have you tried doing a ramp test on the Rcd to see what it trips at. Fuse box looks a few years old. They do weaken off with time
     
  11. Bazza-spark

    Bazza-spark Well-Known Member

    I think the Contactum ones will fit, at around £20 each.

    It isn't I'm afraid.

    Kind regards
     
  12. Clarky94

    Clarky94 New Member

    Just wondering what the cheapest option is - don’t want to change the fuse box at present and don’t have equipment to perform a ramp test
     
  13. Bazza-spark

    Bazza-spark Well-Known Member

    Unfortunately, all options without access to the test gear are going to cost you other than walking away and leaving as is.

    You could get a local spark to ramp test it for you. It will not take him long so shouldn't cost an arm and a leg. Get him to test it both on its own, and with all your normal equipment connected and working. The difference between the 2 readings will tell you if you have any standing leakage that may cause you trouble.

    It should trip between 27 and 30mA at x1 on its own. If it is below that it may be a little oversensitive.

    If you do, come back with your results and we can go from there.

    Kind regards
     
  14. Clarky94

    Clarky94 New Member

    But all this happens when the electricity supplier has a blip and I get the problem
     
  15. Bazza-spark

    Bazza-spark Well-Known Member

    Unfortunately you have to prove it isn't your equipment that is the problem.

    I had to carry out a full EICR for a neighbour and present that with my findings to the supplier before they would do anything.

    Kind regards
     

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