RCD Trip

[ub7rm]

Earlier this evening for no apparent reason the RCD tripped. Through a process of elimination I identified it was something on the garage circuit causing the issue. Any reset of the RCD and having this breaker switched on caused an immediate trip.

Again through a process of elimination I found that it was the microwave to blame (don't ask why its in the garage..). As soon as I switched it on at the socket the RCD tripped. Seems obvious its the mircrowave or perhaps that socket thats to blame.

But the microwave was not in use, or hadn't been used for several hours. The garage is reasonably warm and dry (part of the house). What would cause it to suddenly degrade to such an extent?

 

[EFLImpudence]

It may not be sudden, just the eventual last straw.

However,

I identified it was something on the garage circuit causing the issue. Any reset of the RCD and having this breaker switched on caused an immediate trip.

Ok.

I found that it was the microwave to blame. As soon as I switched it on at the socket the RCD tripped.

How did you manage to energise the circuit so that you could turn on the microwave?

It still may not be the microwave although it is likely.

 

[ub7rm]

I switched everything on that circuit off - then turned everything back on until it tripped. The other things on that circuit are a radio, and LED lamp, garage door opener and the microwave.

The microwave was the last of those I switched on and immediately tripped the RCD. I guess you're saying some of the other items might also be causing leakage current and for whatever reason the microwave just added enough to the medley?

I'm just bemused that it all decided to fall apart late in the evening when everything was 'steady state' / not in use and had been that way for some time.

 

[securespark]

Were the radio, LED lamp and door opener all completely disconnected from the circuit at the time, ie by unplugging, switching off a DOUBLE pole switch or physical disconnection of both line and neutral conductors?
If not, disconnect them all completely (following safe isolation procedures), re-set the RCD and connect just the microwave. Does it still trip?

 

[securespark]

.

 

[EFLImpudence]

Aren't you saying that the first trip happened (out of the blue) when the microwave was not switched on?

Try a kettle in the microwave socket.

 

[ub7rm]

The microwave was switched on at the wall but was not in use.

I just switched everything off at the socket, didn't unplug them. Switched everything back on one by one and when i switched the microwave on at the wall it tripped instantly.

I tried it again this morning and the RCD stayed on. Weird.

I will do a bit more investigation later.

 

[ban-all-sheds]

I just switched everything off at the socket, didn't unplug them.

Although unlikely it is possible that the switches are single pole, and not disconnecting the neutral. Try unplugging.

Switched everything back on one by one and when i switched the microwave on at the wall it tripped instantly.

Try making the microwave the first thing you plug back in and switch on.

Try something else in that socket.

Try the microwave on another socket circuit if you have one on a different RCD.

don't ask why its in the garage

Has it only recently gone in there?

Have you recently got any new electronic items? PC, TV etc?

 

[ub7rm]

No real closure to this except that it has been powered up and operated with no further tripping. Perhaps there was some condensation inside from the last time it had been used. But I wouldn't have thought this was something that a microwave oven shouldn't be able to cope with since they are designed to heat food which typically causes steam. That said it didn't seem 'damp' inside either.

The microwave has been in the garage for the best part of the year and as far as I'm aware there are no new electronic items in use in the house.

 

[ban-all-sheds]

The microwave has been in the garage for the best part of the year

Could have got damp in places not expected to.

 

[EFLImpudence]

Not much has been discovered but it still remains that the first trip was not because the microwave was turned on.

It could just be the current causing the trip because of a fault elsewhere.


Please help yourself and us by doing as asked.

Try making the microwave the first thing you plug back in and switch on.

Try something else in that socket.

Try the microwave on another socket circuit if you have one on a different RCD.

 

[securespark]

Could have got damp in places not expected to.

Ohhh, Matron!!!

 

[ub7rm]

Not much has been discovered but it still remains that the first trip was not because the microwave was turned on.

It could just be the current causing the trip because of a fault elsewhere.


Please help yourself and us by doing as asked.

Its true that the microwave wasnt turned on, but energising it caused an immediate trip. De-energising it prevented any further tripping.

The microwave is now energised and has been used without further tripping (on the same circuit as before). I tried a vacuum cleaner in the same socket and no tripping.

It would seem that damp (which has subsequently evaporated) is a likely cause. Although the garage is not damp, it is colder than the rest of the house and the steam normally generated in use doesn't evaporate away as quickly as 'normal' and over time has caused some internal degeneration. Whatever residual moisture was left from the last time it was used made its way somewhere it shouldn't have and caused it to trip.

 

[EFLImpudence]

It would seem that damp (which has subsequently evaporated) is a likely cause.

Yes, could be.

See how it goes.