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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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  • 0
    I had "nuisance tripping" with a Crabtree Starbreaker  plug in type R.C.D. in a small house once. It sometimes tripped OFF when the cooker oven was turned OFF. I witnessed this myself. Initially I took the cooker off the R.C.D. protected side of the consumer unit. R.C.D. tripping issue then stopped. I found no low insulation resistance readings on the cooker or wiring. I later renewed the R.C.D. I concluded that the inductance of the fan motor was causing a high Voltage spike at turn off, that the R.C.D. didn't like, and that spike caused it to trip off. Perhaps the R.C.D. was on a knife edge anyway. I don't think that I returned the cooker circuit to the R.C.D. protected side of the consumer unit after several visits. Enough was enough.


    Z.
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  • 0
    I had "nuisance tripping" with a Crabtree Starbreaker  plug in type R.C.D. in a small house once. It sometimes tripped OFF when the cooker oven was turned OFF. I witnessed this myself. Initially I took the cooker off the R.C.D. protected side of the consumer unit. R.C.D. tripping issue then stopped. I found no low insulation resistance readings on the cooker or wiring. I later renewed the R.C.D. I concluded that the inductance of the fan motor was causing a high Voltage spike at turn off, that the R.C.D. didn't like, and that spike caused it to trip off. Perhaps the R.C.D. was on a knife edge anyway. I don't think that I returned the cooker circuit to the R.C.D. protected side of the consumer unit after several visits. Enough was enough.


    Z.
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