Electric shower trips MCB when not in use?

[flygrip]

Hi, Everyone. Hope you all had a good break.

The shower in question is quite old, but It has been trouble free for the last few years since I moved in. It is 9.5KW and the MCB is 40A.

The problem is the MCB trips when shower is NOT in use(e.g. overnight). Does anyone have any similar experience? What can I do to diagnose the problem/eliminate the cause? Thanks in advance.

Edit:

There is an isolator switch outside the bathroom. We normally leave it ON all the time.

Only the SHOWER MCB is tripped.

The shower still operates as normal, yesterday we ran it for 30mins and it was fine.

 

[chivers67]

I'd start looking at the isolation switch and see what the connections are like in the first instance - if ok disconnect the shower completely and if it stops this is virtually proving the fault onto the shower unit.

You could look at the shower first to see if there's anything completely obvious that could cause it if it's easy to take the cover off?

Make sure the power is off.

 

[EFLImpudence]

Similar recent post but didn't really come to any conclusion -

//www.diynot.com/forums/electrics/mcb-trips-3-mins-after-switching-off-shower.299242/#2182040

 

[Click-Sure]

Hmm, 41.3A at 230v, 39.6A at 240v (for the old school among us) so the mcb is running very close to its limit, perhaps once the thermal element cools down after a period of time the mechanism is operating somehow?

Which brand of MCB is it, just out of interest?

 

[flygrip]

Thanks for all your replies.

There is an isolator switch outside the bathroom. We normally leave it ON all the time.

Only the SHOWER MCB is tripped. The make is PROTEK.

 

[flygrip]

The shower still operates as normal, yesterday we ran it for 30mins and it was fine.

 

[stillp]

The make is PROTEK.

I suspect that's your problem.

 

[Luckyphil]

Thanks for all your replies.

There is an isolator switch outside the bathroom. We normally leave it ON all the time.

Only the SHOWER MCB is tripped. The make is PROTEK.

I`ve had plenty of Problems with old Protek MCB`s tripping ,( Lighting & Socket Circuits) when carrying Tests all appear ok , I seem to think they tend to nuisance Trip as they get older

Lucky