electric shower problem

[jimboy]

The electric shower unit has worked perfectly for 13 months but know the MCB in the CU trips aftger about 5 minutes of use. The temperature setting of the shower has been turned down from high setting to medium but still breaker trips.
Shower is 9.5Kw, breaker is 40A Type C (Chint NB1-63) in CU as recommended by shower manufacturer !. Cable is 10mm2.
Before buying a new shower (as I suspect the heater coils could have gone faulty although the water temp does not alter) any suggestions as what else to check .

thanks
jimboy

 

[Adam_151]

I'm going to suggest that its not very likely that the shower has gone faulty in this way, they don't suddenly fail in the way that they pull 50% more current, they either fail by stopping working or going bang. And you state yourself that the water temp. doesn't alter, kilowatts don't just evaporate

No, I would point the finger at the breaker going faulty, chint is hardly the height of quality, and I would recommend you obtain a new one and swap it out. (though still chint, you shouldn't mix the make of breaker and the make of cu)


I would however question the use of a type C breaker, a shower should be on type B breaker, and correct me if I'm wrong but your post seems to imply that it was a DIY shower install?, would it be right, therefore to assume that you never checked that the Z's were low enough for the breaker you used? ( and the chance of the Z's being too high for a C40 is quite a bit higher than the chance of them being too high for a B40)

I would install a B40 breaker instead, of course this would be notifiable work, but then again, so was installing the shower...

Regards

Adam