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Jim x321x

wrote in
:

On Wednesday, 24 June 2015 10:59:29 UTC+1, Jim x321x wrote:
Can someone tell me if I can get away with a 45A MCB for a 8.5kW
shower without endagering life and limb? The manual tells me to use a
40A one, but I just happen to have a 45A one. I ask, because those
things aren't cheap.

Probably, as you're not relying on the MCB for overload protection (as
the load is fixed and unlikely to draw a higher than rated current),
merely for short circuit in the event of fault.

What is the cable size an mounting method.?

Owain

It's a 6mm^ T&E cable that is surface mounted all the way to the 8.5kW
shower. (about 4ft goes through surface-mounted conduit.

So, I could use the spare 45A MCB. I also have a spare 20A MCB which I
could swap with the upstairs ring-main's 32A MCB and use the 32A MCB for
the shower instead of the 45A one. Which would be the better option? (I
guess the upstairs ring main would be fine on a 20A MCB, since I don't run
any heating applicances upstairs and its only a 3-bed house.

Many thanks,

Jim