Shower circuit tripping Intermittently when NOT in use

[DetlefSchmitz]

I don't think we yet know the power rating of the shower either. 32A may not be sufficient.

 

[Rhibhi85]

From what you have told us ,I suspect what is happening is when you switch off the ceiling pull cord switch ,that is when the MCB trips. When you next go to use the ceiling switch nothing works ,as the MCB is already off.
You could check the MCB , after switching off the ceiling switch ,each time shower is used. If it is tripping the MCB as described ,that points to a suspect ceiling switch ,possibly the MCB.
You will at some point need to engage an electrician to test and rectify.

So, I can freely turn it off and on after using it, I try it several times throughout the day and after using other things in the house just to see if it’s triggered anything. It doesn’t seem to trip immediately after switching it off, ever. It just randomly trips at some point during the day/night/morning.

Nice to see some cowboy crowbarring a “foreign” MCB into a different donor consumer unit.
always points towards someone with a make do attitude. the quality of the installation may prove to be the root cause of this problem.

Don’t even get me started on the electrics in this place! Everything is daisy chained off of something else apparently, and when I moved in and tried to change the wall lights in the living room (alongside the garage) found out they had been hard wired straight into the mains - thankfully that got sorted out but I have a feeling there’s a web of lies behind the walls!
Why I thought the shower might be something else is because it’s been fine for the three years I’ve been here, and don’t recall any problems before that (my grandparents lived here before me). will see what happens with leaving the pull switch on (if I can bear the standby lights!).
Definitely getting someone out to look at it once it is safe to do so as I’m in isolation at the moment, just wondered if I could do some fault finding before hand so it’s more obvious a fix for them.

thanks again all!

 

[Rhibhi85]

Nice to see some cowboy crowbarring a “foreign” MCB into a different donor consumer unit.
always points towards someone with a make do attitude. the quality of the installation may prove to be the root cause of this problem.

Don’t know how to find this out without a manual for it (assume my grandad ‘filed’ it away somewhere before he died so safe no human will ever see it again!). From a look online, I think they made this shower in 9.0 and 9.8 kw. Would this sort of fault just start happening 7 years (possibly more) after installation if it wasn’t fitted correctly with the right rated board? Or would it have always happened?

 

[Rhibhi85]

Don’t know how to find this out without a manual for it (assume my grandad ‘filed’ it away somewhere before he died so safe no human will ever see it again!). From a look online, I think they made this shower in 9.0 and 9.8 kw. Would this sort of fault just start happening 7 years (possibly more) after installation if it wasn’t fitted correctly with the right rated board? Or would it have always happened?

Scratch that, had a brainwave and looked on the underside of the unit facing the floor and it seems to be the 9.0kw model.

 

[DetlefSchmitz]

OK - whatever assumptions you make - 32A is not enough. Probably the MCB has gradually been suffering and the whole thing needs looking at by a proper electrician. The cable used may also not be up to the job!

 

[terryplumb]

9 KW shower is really too high for a 32 amp circuit ,and over time would very likely bugger the MCB.

 

[Rhibhi85]

Thanks everyone. I will chat to an electrician about replacing the MCB when lockdown is over then, yes?

 

[SUNRAY]

Looking at the pictures I'm not sure I see a cable big enough for a 9KW unit or for that matter a 32A MCB.

 

[RF Lighting]

Maybe something leaks inside the shower and shorts something out when everything cools down after use

 

[Taylortwocities]

Unless I have misunderstood, the MCB can trip even when the isolation switch is off.

@Rhibhi85 can you confirm?

 

[SUNRAY]

Unless I have misunderstood, the MCB can trip even when the isolation switch is off.

@Rhibhi85 can you confirm?

I get the impression it only trips with the isolator off. I'm still suspecting a faulty switch.

 

[DetlefSchmitz]

I think myself that the MCB, which is by now well and truly screwed, gets hot and trips some time after the shower

 

[securespark]

There has to be a fault in the part of the circuit between (and including) the MCB and the supply terminals of the DP switch.
So that's either the MCB, the cable or the switch.
I suppose there could be a nail in the cable somewhere?

Be interesting if we could see inside the CU, but only if the OP is confident.

Looking again at the second piccy, it looks like the grubby white cable with the GY strapped to it goes over the top of the shower CU, into the adjacent cabinet, drops down and reappears as it comes up into the bottom of the shower CU.

 

[Taylortwocities]

The usual obvious fault location is in the switch itself. @Rhibhi85 have you looked in there? Power off first please!!

 

[Rhibhi85]

So I’ve left it on at the pull cord since Wednesday and it hasn’t yet tripped again... will continue the experiment over the weekend and report back!

The usual obvious fault location is in the switch itself. @Rhibhi85 have you looked in there? Power off first please!!

if it does turn out that it only trips with the switch off could that be a problem with the switch? If so, should I replace it? I’m confident changing plug sockets, light fittings and light switches... will this be the same sort of animal?

apologies if I’ve missed any other questions?