"fred" wrote in message ...
In article ,
Vass writes
6mm cable
45W switch
into 40 trip switch on fusebox
all ok?

If you're not at the shops already then 10mm2 would be more future proof:

6mm2 in free air or trunking is ok up to 8.5 kW but you can lose 5% of the
power in the cabling on a long run. If you have a run through insulation
then
it should be 10 (or move it out of the insulation).
10mm2 is needed for 9kW or above and will lose less power to the cable.

Thanks Fred
I was wrong, I have 10mm and the Shower is 10.5kW
I have opted for a switch to be situated outside the bathroom
that way the cable will run straight up from the garage to the airing
cupboard
which is next to the bathroom and where the back wall of the shower is
so becomes simple.
proposing then
10.5kW shower
10mm cable
45w switch
40 trip switch on RCD'd CU
--
Vass