8.5 kw shower cable size

TopTrumper · Posted: Sat Nov 15, 2008 9:53 pm

GaryMo wrote:

They would need to take my professional advice.
I would recommend an alternative route thus avoiding insulation. If that's not possible then I would inform them that I could install a 10mm cable but it's only rated at 36A and can only supply a shower rated at a maximum of 8kW.

I would NOT install a shower with a rating higher than the current carrying capacity of a cable.

Why is this so difficult to understand? It's like asking me to put a square peg in a round hole - something has to give.

I understand.
Completely.

GaryMo · Posted: Sat Nov 15, 2008 9:56 pm

Why the rolling eyes then?
Seriously, is there something you don't understand or don't agree with?

equitum · Posted: Sat Nov 15, 2008 10:47 pm

TopTrumper wrote:

GaryMo, fair enough, point taken.
Answer me one question, if the OP had said he wanted to install this shower, what cable would you advise him for the 3 metre run?

http://www.alertelectrical.com/Electric-Power-And-Mixer-Showers/Mira-Showers/Mira-Electric-Showers/Mira-Vie-108kw-Electric-Shower-Satin-Chrome-D62127.asp

From the MI.....

"
The electrical installation must comply with the “Requirements for Electrical Installations” (commonly referred to as the IEE Wiring Regulations), or any particular regulations and practices, specified by the local electricity supply company in force at the time of installation. The installation should be carried out by an electrician or contractor who is registered, or is a member of, an association such as:
National Inspection Council for Electrical Installation and Contracting (NICEIC), throughout the UK
The Electrical Contractors Association (ECA), England and Wales
The Electrical Contractors Association of Scotland (ECAS)
"

Personally I would have advised the OP that if he doesn't know what cable size to use he/she is not competent to install it, and its not a suitable DIY job. It strikes me odd that the OP is aware of the thermal insulation derating issue as most "laymen" would not consider it..

TopTrumper · Posted: Sat Nov 15, 2008 11:04 pm

GaryMo wrote:

Why the rolling eyes then?
Seriously, is there something you don't understand or don't agree with?

It means you just made yourself look like a right soft c*nt

GaryMo · Posted: Sat Nov 15, 2008 11:07 pm

Very classy

equitum · Posted: Sat Nov 15, 2008 11:07 pm

Errrr....toptrumper, I have never known a name so apt as yours, well done !!

EDIT: Please explain why you are not ashamed of giving advice that could potentially cause a fire and at best is contrary to any reg since about the 2nd edition without having a rethink and perhaps an admission you were wrong ?

RF Lighting · Posted: Sat Nov 15, 2008 11:10 pm

GaryMo wrote:

Very classy

Well personal insults are all he can resort to to try and make you look foolish, as your advice about cables in insulation can't be disputed, what with it being right and all.

GaryMo · Posted: Sat Nov 15, 2008 11:12 pm

Hence I'm not biting, it's not worth the effort.

securespark · Posted: Sat Nov 15, 2008 11:18 pm

I too am puzzled.

Can you please tell me what you would do in the scenario you have described and your reasons for doing so.

ban-all-sheds · Posted: Sun Nov 16, 2008 1:02 am

NotHimAgain · Posted: Sun Nov 16, 2008 7:14 am

Do nothing - oh that won't do will it - after all there are loads of solutions.

Start by reading 523.7 - in particular the second and third paragraphs. Note to that the cyclic nature of the load maybe taken into account (para 1).

So you could select a different installation method (in the literal sense) and use something other than 70 degree C PVC.
Just pick you cable and de-rate it by 50% - XLPE perhaps or bare MI maybe, the list goes on.

You could also consider using cables of different sizes to cope with the restrictions on heat loss in the loft.

No doubt someone will mention heat transfered via connections, and the problems of actually making those connections but these things can all be solved.

Next

hairyben · Joined: 06 Oct 2008 Posts: 644 Location: Morocco

10,800 / 240 = 45

Using parallel runs of 6mm will allow 45A+ with any of the new 10X methods.

Or parallel 4mm, wap some trunking round it in the wall and call it ref method A, 26A x2.

Not the norm in domestic and never done it this way myself, but heard it discussed, any thoughts?

cos showers are getting more and more power hungry and people are stuffing insulation everywhere. Gone are the days when people would be overjoyed with a 7.2 mira supreme, and they wonder why their electric bills hit the roof.

tSpark · Posted: Sun Nov 16, 2008 1:07 pm

Had to fit a similar size shower before, that too would only take 10mm. I needed to get through insulation to get across to bathroom roofspace, so I ran 16mm to the shower pullswitch and then the short distance from pullswitch (i kept battened above insulation) to the shower in 10mm,

GaryMo · Posted: Sun Nov 16, 2008 1:17 pm

Nothing at all wrong with that.

How did you find terminating a 16mm and 10mm in a pull switch? I'm normally tearing my hair out when connecting 2 x 10mm cables even with the deepest backbox I can lay my hands on!

In fact, I hate pull switches

tSpark · Posted: Sun Nov 16, 2008 1:24 pm

I'm getting wise, I wont tackle something like that without having at least one spare patress box at hand, two, if i know im in that short tempered mood

Pull switchs are great for one thing, loose terminals, hot contacts and replacement!! (ok three)
Top of the list of things I hate doing at the top of a ladder!