Shower circuit tripping Intermittently when NOT in use

[securespark]

We do suspect it could be an issue with the switch, but it's odd it trips with the switch off.

Has it only ever tripped with the switch off?

It would be good if you could do as TTC suggests, then post the picture here, but you need to turn the power off (and given the oddities you have found, best to turn the whole lot off at the main switches).

 

[EFLImpudence]

Tripping while the switch is off is strange. Of course, it could have tripped when it was switched off - sometimes.

Don't RCDs just do that sometimes and no one really knows why?

 

[securespark]

Well, I remember a board change I did in the early 2000's.

It was a "standard" split-board. Install tested OK, but when switching back on with appliances plugged back in, the RCD tripped when the main switch was turned off. I traced it to a larder fridge that had N/E reversal in the plug.

Quite how is another question, but sorting that out stopped the tripping.

Edited for clarity.

 

[securespark]

But aren't we talking about the breaker here?

 

[EFLImpudence]

But aren't we talking about the breaker here?

Oh yes. Beg pardon.

 

[flameport]

Quite how is another question,

More common if the switch is worn, and the two poles don't operate at the exact same time, so N disconnects first leaving just L connected, the N-E fault than takes all of the load current for a brief time until the L disconnects, but that can be enough for a fast RCD to trip.
Also depends on several other factors such as capacitance of the cables and connected equipment, differences in impedance between L-N and L-E and so on.

 

[securespark]

Appreciate what you're saying, but the CU was BNIB.

 

[Rhibhi85]

Ok so the experiment continues. I left the pull cord ON constantly and just turned it off at the shower button each time (usually I would do that and then pull the cord to turn that off too). When I left the pull cord on it didn’t trip at all... but here’s the weird bit.. The last week or so the outside temp has been lower due to the weather, as soon as the temperature outside started heating up again the RCD tripped in the night again.

The mystery continues! Hopefully got someone coming to look at it soon but it’s been a nightmare finding someone to come out!