11kw shower cable size?

[Chris14]

For 11kw shower what cable size is required for 15m run?

 

[telectrix]

Group showers. Like it. AND THE GROPING FACTOR.

 

[GLENNSPARK]

Who in their right mind would want an 11kw shower?

greasy monkeys perhaps:joker:

 

[Mr Mark Sparks]

Who in their right mind would want an 11kw shower?

The same loony who surprises you with an 11 kw range oven with induction hob, warming draw twin oven and grill after saying its a double oven and gas hob......

 

[Stroppy]

At least then you can fry bacon on the cable as a bonus.

 

[Rockingit]

The same loony who surprises you with an 11 kw range oven with induction hob, warming draw twin oven and grill after saying its a double oven and gas hob......

Bit of 6mm and a 32 it is, then.

 

[Mr Mark Sparks]

Bit of 6mm and a 32 it is, then.

Indeed it still is fingers crossed Xmas day.

 

[monkeyelectric]

greasy monkeys perhaps:joker:

A 9kw is just as good at getting the grease out of a monkeys fur and i would know

 

[kingeri]

My 8kw serves me well, usually use it on half power setting as well. Still miss the power shower from the old house though. And my 8kw is on 10mm and a 32a breaker for info

 

[Knobhead]

I think I found him..

View attachment 18892

Oi!
Who said you could use my photograph!

It was a bad hair day.

 

[flyinghigher201]

lol one of the things ive been doing at college is cable calcs. very interesting

 

[alanl]

6mm clipped direct just on the limit, but you'd need a OCPD of 50A, so 6mm is out of the equation.

Why?
433.3.1 (ii)
A shower is a fixed resitive load, so very unlikely to be subject to overload current apart from a fault.
It has fault protection via the RCD (and the 50A CB), any fault will be cleared in less than 0.3 seconds that the RCD takes, so a 50, or even 100A CB will be compliant.
(of course so long as cable length, Zs, grouping/reference all comply too)

 

[telectrix]

the shower is 47A so the OCPD needs to be >47A but less than the Iz of the cable. so a 50A MCB. this means that the cable Iz must be > 50A so it's got to be 10mm.


what's the RCD got to do with overload protection?

 

[alanl]

No, sorry, you are wrong.
It is a fixed resistive load, so does not need overload protection, it must have fault protection, which the RCD will provide.

 

[telectrix]

nothing to do with the type of load. it's the cable that needs overload protection. what's the RCD going to do in the case of a short circuit L-N?

 

[alanl]

433.3.1
There is no need for circuit protection if the load is unlikely to carry overload currents. A shower will not overload unless it has a fault. No-one is likely to fix the circuit directly to the outgoing RCD terminals, so fixing it to a CB rated higher than the current carrying capacity of the cable is quite acceptable in such circumstances, so long as the cable can carry the current of the appliance.
A L-N fault will cause many hundreds of amps to flow (in most installations), meaning any CB fitted, whether 50 or 100A will trip virtually instantly. It is only in fault conditions that a L-N short will occur.
Hence it is compliant to run a cable with a 47A capacity, feeding a 45A fixed load appliance, fed via a 50A CB, as there will be fault protection, both via any CB fitted, and via the RCD which will have to be fotted in any domestic premises. There will be no overload protection, but that isnt required, as stated in 433.3.1.