Electrical Question

Shower question?

We have recently had a loft conversion done & the electricians have fitted all the cabling for the shower ready. But I am not sure what size electric shower I can go to? Can anyone help (I am reluctant to go to the electricians as they are not the most helpful!) but of course they will be coming back to wire it in
The wiring certificate says circuit 2 shower, Type of wire A, circuit conductors live 10 / cpc 4 & A rating 40.
Many thanks

6 Answers

They should have asked you what size unit in KW you were putting in. If you buy a 13KW unit i would like to see their reaction. Cables lose voltage over distance, and also HEAT UP.

You need to talk with the electricians no matter how awkward.


Answered 3rd Aug 2012

pjb plumbing & heating

Member since 17 Apr 2012

10mm will do most domestic showers on the market there are obviously bigger and without seeing lenth of run method of installation its not a guarantee so you should ask your electricain they will let you know the kw allowed. It's in there interest as well being that they are the ones who will install it or not if you get the wrong one by not asking them. Personally though if you cannot ask the guys who are doing the job for you questions then maybe it's time to look for another electrician.
Good luck

Answered 3rd Aug 2012

Triumph Electrical.

Member since 2 Apr 2012

(9KW) 9000 divided by 230volts=39.13amps just inside your 40AMP rating.
(voltage drop per ampere per meter=4.4mV)
so a 30 meter run would give aprox 5volt drop(negligible).

Answered 3rd Aug 2012

kevin cassidy building contractors

Member since 16 Dec 2010

A 10.0mm cable will be fine with any shower up to 10kw.

Answered 3rd Aug 2012

Electrical Safety Services

Member since 17 Oct 2011

It's usually the size of the shower which dictates the size of the cable, as stated above. If 10mm cable has been already installed then that would imply that you should be looking for a shower rated at around 8-9kw but there are other factors to consider. I think you would be better consulting the people that have installed the cable as they a better knowledge of this particular installation, hope this is helpful

Answered 4th Aug 2012

Efficient Electrical

Member since 1 Aug 2012

The calculations depend alot on installation method and length of circuit run. To be safe and as a guide for you with the info you provided, look at 8Kw showers (8000 watts). 8.5Kw max. If the length of cable run is very short and cable is installed properly then it is possible to up rate the MCB (currently 40A) to 50A which will enable you to get a more powerful shower.

As it is I would personally stick with an 8Kw / 8.5Kw shower.

They should also install an appropriate isolator for whichever shower is installed.

Answered 5th Aug 2012

Sensor Electrical Services

Member since 6 Mar 2012

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