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Radio interference of RCD's?

alanblaby
I've got an ongoing problem with a randomly tripping RCD.

It started 3 months ago, lost power in the middle of the night. 3 circuits (sockets/cooker/shower) fed by the one RCD.

Initial thoughts were to faulty appliances. But, the trip has been random, apart from it is usually late at night/early morning.

The trip is usually sometime between midnight and 2am. It cannot be pinned down any closer as the flatowner is in bed!

Once reset, it stays on for a week or more.

So far: All fixed wiring has been tested, and all OK. RCD (old Crabtree, plug in type, 15-20yo) has been changed and

ramp/time tested, 27mA ramp, 18/43 time. Earth leakage with my basic meter gave a 6mA reading.

It went again last night after a month of non-tripping.

I think I've covered all bases, and will now be changing the CU for a metal clad all rcbo board.


So, what do you reckon? I'm stumped now, and thoughts have turned to radio interference causing the RCD to trip. 

It's a long shot, but I cant think of anything else that may cause it.

Any thoughts?
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    The trip is usually sometime between midnight and 2am.



    Done any insulation tests?  I've seen faults at times like that (actually it was on a network cable and regularly at about 5am, but same principle) - turned out it was a faulty connector that was responding the the building cooling down after the heating shut off at 18:00 - the timing was surprisingly regular despite the variations in the weather.


    So my first suspicion would be a damaged cable or damp accessory that's within a hair's breadth of shorting to earth, and all it needs is a bit of cooling to contract a bit of metal somewhere, or a slight bit of extra condensation, or even being walked over by a small rodent to tip things over the edge.


    Likewise, look for anything that might turn on automatically at such times - e.g. a frost 'stat set a bit too high.


      - Andy.
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  • 0

    The trip is usually sometime between midnight and 2am.



    Done any insulation tests?  I've seen faults at times like that (actually it was on a network cable and regularly at about 5am, but same principle) - turned out it was a faulty connector that was responding the the building cooling down after the heating shut off at 18:00 - the timing was surprisingly regular despite the variations in the weather.


    So my first suspicion would be a damaged cable or damp accessory that's within a hair's breadth of shorting to earth, and all it needs is a bit of cooling to contract a bit of metal somewhere, or a slight bit of extra condensation, or even being walked over by a small rodent to tip things over the edge.


    Likewise, look for anything that might turn on automatically at such times - e.g. a frost 'stat set a bit too high.


      - Andy.
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