electric shower need help!!!!

[Franciszek]

Have had an electrician to wire a new shower but have some safety issues that need clarifying the shower has been hard wired back to new breaker but has not been wired at the shower end as it waiting to be plumbed in and tiled.The house is owned by a housing association and on annual inspection an number of items where picked up.The shower is a Mira sport 9kw with a run of about 12m which is surface mounted in a capping he used 10mm cable saying if we ever wanted to upgrade then we could without us having to re wire.He has used a 50amp breaker the book says 40 amp how dangerous is this the other electrician says the shower could catch fire under fault conditions need some good feed back on this please have got all details on rcb if needed.
Thanks

 

[ban-all-sheds]

It should be 40A - not following the manufacturers instructions is a contravention of the Wiring Regulations.

That said, I can't envisage a fault which would cause the shower to catch fire on a 50A breaker but not on a 40A.

Your biggest personal concern should be that if anything did go wrong with the shower the manufacturer/retailer could use an incorrect MCB as an excuse to wriggle out of liability, even though it had nothing to do with the failure.

 

[skenk]

Generally the MCB protects the cable, not necessarily the appliance but if the manufacturers instructions (MI) say it should be 40A then it needs to be to comply with wiring regs. Not a big job to change it for an electrician but NOT recommended for DIY.

Are you sure it's capping and not mini-trunking?

EDIT: 2nd time tonight beaten to it by BAS!

 

[securespark]

The only issue I would be concerned about is the derating of the 10 milli due to the use of trunking.

But I don't have the good book here to check.

 

[Franciszek]

Generally the MCB protects the cable, not necessarily the appliance but if the manufacturers instructions (MI) say it should be 40A then it needs to be to comply with wiring regs. Not a big job to change it for an electrician but NOT recommended for DIY.

Are you sure it's capping and not mini-trunking?sorry my mistake it is mini trunking thanks for reply

EDIT: 2nd time tonight beaten to it by BAS!

 

[ban-all-sheds]

The only issue I would be concerned about is the derating of the 10 milli due to the use of trunking.

But I don't have the good book here to check.

Not a method listed for T/E, but it is Method B for general multicore cables in 4D2A, and 10mm² is 52A.