On 06/08/2013 15:53, Caecilius wrote:

2. An outside armoured cable with a low live/earth resistance when
wet. Discovered with a megger, cured by disconnecting the circuit.

We started getting occasional RCD trips - every one being at at 10
o'clock at night. This was precisely when the time-switch for our garden
pond pump switched off (it's a 240v pump connected by 10m or so SWA cable).

Now I leave it running 24/7 (better for the external filter, apparently)
and no more problems. So it was either the time-switch or some weird
induction effect between earth and the armour wires when the voltage was
switched off.


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Reentrant