Shower cable sizing

[glen.mason]

There seems to be a lot of ambiguity and difference of opinions on the Forum regarding shower cable sizing. I have one to fit, 9.7Kw through a seperate RCCB and 50a MCB shower unit via a Henley block using 16mm tails. @ 11m run - 6m capped trunking, 3m under floorboards and 2m clipped direct in the loft [is this Ref. method 'B' or 'C' or an average of the two?]no insulation or grouping. 4D5 table for C gives 47a = 6mm. Manufacturer advises max of 45a but does not stipulate size. Irrespective of possible future events, whats wrong using 6mm?

 

[Sintra]

Without taking into account any other factors your cable will have to be rated above 50A as you have stated you are using a 50A mcb for overcurrent protection.

 

[chris gray]

haha that made me chuckle.
sometime i cant see the wood for the trees either

 

[Bromd123]

I think I'm right in saying that 6mm can only be used on showers up to 8.5Kw after that you need a 10mm csa

 

[Deleted member 9648]

It's no different to any other fixed load. The cable rating must exceed the rating of the protective device taking into account installation methods rating factors,and the maximum volt drop must not be exceeded.

 

[bydand1897]

The size of cable will all depend on the lenght of run and diffrent factors.
You will need a 10mm T&E, as one of the other posts said, a 50A breaker is too large for a 6mm cable.