Wilex nsb32 tripping when shower turned on

[wrinklypeter]

Help!
A registered electrician fitted a new wylex consumer unit for me and everything works great - except...
The electric shower in the bathroom (which as a separate feed from the consumer unit - also connected by the same electrician) trips about 10 seconds after the shower is switched on. Reset the MCB, and it's fine for about another 10 seconds, and then it trips again.
Changing water temperature does not appear to have any effect on the tripping problem. Even when the shower runs cold, it still trips.
Electrician cannot find any fault with shower, or wiring. Any ideas?

 

[JonoPashley]

32A is too small for the load? what is the power of the shower?

 

[ColJack]

what size shower?
32A is barely enough for a 7.5KW shower..

 

[RF Lighting]

Is there a little test button on the circuit breaker?

 

[ColJack]

it's clearly an overload..

the element works at full power irrespective of the flow rate ( until the over temp limit is reached of course.. )
so even when run "cold" it's just that the flow rate is high enough that the element cannot add any significant heat to the water as it passes through..

 

[Goldberg]

Faulty MCB.

 

[LiamPope]

Faulty MCB.

Could be - curves say about 70A minimum to trip a 32 in 10 seconds, which = no domestic electric shower I've ever seen.

Doesn't hide the fact that it's incorrectly specified even for a 7.5kW shower

 

[Goldberg]

If the shower is 7.5kW then a 32A Type B sounds perfect to me.

On the other hand, if the shower is 8.5kW or more, it could explain why the MCB has gone faulty.

 

[ColJack]

I must apologise for my earlier tone, I was a bit miffed and feeling rather confrontational after reading another post in GD where someone was bragging about kicking an unconcious bouncer in the head 3 times..

I must count to 100 before posting after reading posts from idiots..

 

[Spark123]

Faulty MCB.

Could be - curves say about 70A minimum to trip a 32 in 10 seconds, which = no domestic electric shower I've ever seen.

Doesn't hide the fact that it's incorrectly specified even for a 7.5kW shower

The general BS7671 specs may say that but these err on the side of caution - the manufacturers info might show otherwise.

 

[ColJack]

BS7671 curves flatline at 160A.. up to about 13 seconds before the curve bit starts

 

[wrinklypeter]

My apologies for being tardy in replying...everyone! - and thanks for all your very welcome replies!
The shower is a Gainsborough 10.5 SDL - so I'm assuming that it's a 10.5kw shower.
From the responses you've given me, it looks as though the nsb32 mcb is too small for the 10.5kw load. Can you suggest the right mcb?
I think that I'll fit a replacement - Don't trust the electrician who fitted the loriginal one!
Cable looks to be 10mm FTE - I assume that's ok?

 

[ColJack]

you'd need a 45A breaker for a 10.5KW shower..
I'd recommend getting a sparky to fit it ( but maybe not the original one ) as they would be able to confirm that the cable size and the routing of it make it suitable for the load..

changing the breaker is notifiable anyway so you'd have to pay the LABC fees to do it properly..

 

[LiamPope]

Amazing - how can somebody like coljack be out of work when someone who thinks a 32A breaker is OK for a 10.5kW shower (and who isn't even pointed in the right direction when faultfinding by the said breaker's constant tripping) is presumably gainfully employed?

 

[SUNRAY]

Amazing - how can somebody like coljack be out of work when someone who thinks a 32A breaker is OK for a 10.5kW shower (and who isn't even pointed in the right direction when faultfinding by the said breaker's constant tripping) is presumably gainfully employed?

That I'm afraid is what life is all about, I'm sure it will get better though.