Why does my trip switch keep tripping out during the night?

[RATTER15]

We dont use anything electric during the night that we don't use during the day except the night storage heaters which are on a different system, also it is more likely to trip out in bad weather but only during the night, We have recently had a new water heater fitted and all the electrics were tested then and was all fine. I have tried isolating different systems but it only appears to trip when all systems are on.

Any ideas?

[The Builder]

RCD I guess, Ratperson?
A right can of worms this can be :o(
Bad weather.... maybe an outside light letting in water. You sould switch off the relevant lighting circuit one night and see if it still occurs. The problem with that is that will only show up a live to neutral fault. Yours may be a neutral to earth fault. You'd have to get into the consumer unit and disconnect the right neutral wire to identify that.

Water heater? They are one of the worst things for "earth leakage currents". Everything will test OK, but a very small current can be leaked in normal operation. Add this to other leakages such as freezers, and it may be enough to trip your RCD (30mA)

If you get someone in, he may put a clamp meter on the circuit to measure leakage. He might also swap circuits around so that the worst culprits are separated from each other.

All guesswork though. If no luck with isolating, then quite possibly a neutral-earth fault which, as I mentioned, you would have to isolate inside the CU.

[The Builder]

Correction .......... ^^^^

Bad weather.... maybe an outside light letting in water. You sould switch off the relevant lighting circuit one night and see if it still occurs. The problem with that is that will only show up a live to EARTH fault. Yours may be a neutral to earth fault. You'd have to get into the consumer unit and disconnect the right neutral wire to identify that.

oops ..........

[BRIGHT SPARK]

Which circuits switch go off when the trip goes......can you give the details given on the front of the trip.

[BRIGHT SPARK]

sorry..which circuits go off

[The Builder]

^^^ Come back Rattman ... the cavalry's here ;o)

[RATTER15]

Hiya, sorry ive been at work. I think I may have sorted the problem, our dishwasher died today and on pulling the machine out found water underneath, it has probably been leaking on the wiring, I still find it a little strange that it usually happens during the night. We don't have any outside lights so cant blame that.

[evedawn]

Hmm my husband suggests the following: it trips at night because night time = central heating on. When heating is on it = condensation. Condensation them gets "drawn up into wiring". Kinda makes sense ??

[RATTER15]

Evedawn, we don't have central heating but thanks for input.