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PLEASE IGNORE - DUPLICATE THREAD - 13A Socket with RCD trips circuit breaker.

Discussion in 'Electrics UK' started by Pickup, 13 Jan 2019.

  1. Pickup

    Pickup

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    Hi,

    Looking for some advice please.

    There is a 2G RCD socket (13A 30mA) in the ladies changing room of my son's gym (installed under previous owner) presumably to allow clients to use hair straighteners etc.

    The socket appears to be working OK however when the "Test" button is pressed on the faceplate both the socket breaker and the circuit breaker (20A 30mA) on distribution board trip.

    Is this normal or is the test circuit on the socket faulty?

    I believe the 17ed regs allow an "ordinary" socket to be used if it is more than 3m horizontally from zone 1, and that "fixed partitions may be taken into account where these effectively limit the extent of locations containing a bath or shower".

    Does this apply only to domestic premises or does it apply to commercial premises too?

    The showers (with shower trays) are in stud partition cubicles (full height wall) in front of which is a partition type cubicle (of the kind typical found in the toilets of commercial premises) to provide a private drying/changing area.

    What would be considered an appropriate distance from the cubicle to the socket if it wasn't RCD?

    Thanks
     
  2. EFLImpudence

    EFLImpudence

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    If it is 20A/30mA, i.e. an RCBO, then yes it will trip as well. In this case the socket does not need to be 30mA RCD but no harm done.
    If it is just a normal 20A MCB, then it should not trip.

    No. All sockets must be covered by a 30mA RCD - either in the DB or the socket.

    The socket must be at least 3m from the edge of the shower tray. This includes going round corners.
    Look at it another way. If you plug in a 3m lead, it must not go over the edge of the shower tray by whatever route.

    Doors do complicate the matter but in such a situation, you would probably be wise to ignore them if the children are likely to take appliances through them.

    N/A - 3m. They must be on an RCD.
     
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  3. Pickup

    Pickup

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    Thanks for taking the time to reply so comprehensively!!.

    This all cropped up because the circuit has "suddenly" started tripping - 4 mornings this week at about the same time - staff rest the breaker in DP and all is well until the next day.

    They (the gym) had some new (electric) hand driers fitted over Christmas break and staff were concerned they were causing the problem. I went down this afternoon and tried the (new) hand driers, the ((old) hardwired) hair driers both individually and in all possible permutations and couldn't replicate the fault.

    One of the staff mentioned that a client had been using/going to use hair straighteners when it tripped. So I "tested" the RCD and the RCB0 tripped.

    Will get someone to replace the faceplate (as the circuit is protected by the RCB0) with a regular one.

    Thanks again.
     
  4. EFLImpudence

    EFLImpudence

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    As said, whilst an earth fault causing the socket RCD to trip will cause the DB RCBO to trip as well, an earth fault on the circuit between the DB and the socket would only cause the DB RCBO to trip but not the socket RCD.

    So, for the socket RCD to trip the earth fault must be in the socket or in something plugged into it - the straighteners.
    Could the socket be wet inside?

    If just the DB RCBO is tripping sometimes, the fault could be virtually anywhere else.

    The same time daily sounds like something that is timed - heaters?
     
  5. SUNRAY

    SUNRAY

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    It is years since I've come across a non maintained RCD (I hope that's the correct description) testing to earth, to the point I'd be concerned if I found this happening.
    Anyway back to OP, are you sure this is not a person pushing the test button every day? Say a cleaner?
     
  6. Pickup

    Pickup

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    Hi folks,

    Sorry should have been clearer - I'll have a look inside the socket for moisture but I'm pretty sure that the gym's client (with the hair straighteners) is pressing the test button on the faceplate. The staff, though not sure, think it has only happened on days she's been in - it does happen about the same time (just after an 8am class) but doesn't happen every day

    Thanks again.
     
  7. Taylortwocities

    Taylortwocities

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    Many RCD sockets are labellled “Test before use”. So perhaps she is following instructions!
    As above, the second RCD isn’t needed. The easy solution is to change the socket to a non-RCD one!
     
  8. EFLImpudence

    EFLImpudence

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    I do not know what that means - correct description or not.

    Why? It seems the logical thing to do.
    That is, have the test circuit on RCD sockets simulate a fault to earth.

    RCCBs cannot do this because they are not connected to a CPC, therefore the test circuit causes an imbalance between L and N.
     
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