10.5 kW shower - advice/help required

[Paulr999]

Hi,
I hope someone can help as I'm getting conflicting advice re the fitting of a 10.5kw electric shower.

my 8.5kw unit recently died and I bought a 10.5 kW Triton shower to replace, which is turning out to be more problematic than I thought :
2 people say I need a bigger cable than the 10mm cable already installed while 2 others say the existing cable is fine. I stopped in at a large B&Q yesterday and their bathroom advice guy says they always fit 10.5kw with a 10mm cable and mentioned section/paragraph/something 27 as the guidelines they follow.

i have a 45amp circuit breaker for the unit already

so what should I do ? Get retired or fit the unit with the existing cable ?

thanks in advance

 

[Richard Burns]

A 10.5kW shower would (in principle) pull about 46A in current a 10mm² flat twin and earth cable is only rated for that level of current if the cable is clipped directly on the surface of a wall, buried in plaster in a wall or laid in contact with the inner plasterboard of an insulated stud wall.
If the cable is buried in insulation, in trunking or conduit then the cable is not rated for that load and you would need to use 16mm² cable (so long as it was not buried in insulation).
Strictly according to the regulations the 45A circuit breaker is also not sufficient and you would need a 50A breaker that would then prevent you using 10mm² cable unless it was only clipped direct (or in plaster).

The best solution here would be to return the 10.5kW shower and replace your shower with another 8.5kW shower.

 

[HandySparks]

A 10.5kW shower would (in principle) pull about 46A in current a 10mm² flat twin and earth cable is only rated for that level of current if the cable is clipped directly on the surface of a wall, buried in plaster in a wall or laid in contact with the inner plasterboard of an insulated stud wall.
If the cable is buried in insulation, in trunking or conduit then the cable is not rated for that load and you would need to use 16mm² cable (so long as it was not buried in insulation).
Strictly according to the regulations the 45A circuit breaker is also not sufficient and you would need a 50A breaker that would then prevent you using 10mm² cable unless it was only clipped direct (or in plaster).

The best solution here would be to return the 10.5kW shower and replace your shower with another 8.5kW shower.

You may well find that the "10.5kW" rating is quoted for a supply voltage of 240V. If so, the current drawn at 240V will be less than 45A (and even less at 230V), so a 45A breaker will be fine.

Provided that the cable isn't covered in loft insulation, I'd say that 10mm² will do the job.

 

[Paulr999]

Thanks for the replies guys.
Ive taken the less costly route of buying a 9.5kw shower unit - which thanks to the Tesco vouchers double value promo ended up costing nothing..... So hopefully the 10mm cable is sufficient now