shower cable size

breca · Posted: Wed Feb 07, 2007 2:05 pm Post Subject: shower cable size

If i fit a 8.5kw shower with a 10 metre run to consumer unit would a 6mm cable be ok or would i nedd a 10mm cable.

davy_owen_88 · Posted: Wed Feb 07, 2007 2:11 pm Post Subject:

6mm^2 twin and earth will be sufficient for a 37A load providing it isn't subject to other derating factors (high ambient temperatures, running through insulation in walls/lofts, grouping factors etc.)

Let us know how you intend to install the cable and then we can verify if 6mm^2 will be ok. It might be worth using 10mm^2 cable regardless though so if you decide to upgrade the shower in the future you don't need to rip out the old.

Davy

ricicle · Posted: Wed Feb 07, 2007 2:15 pm Post Subject:

6mm² will be fine on a 40Amp mcb as long as the cable doesn't follow a route through thermal insulation and is not grouped with other cables
Are you aware that this work is notifiable to your local building control under Part P of the building regs?
Most manufacturers recommend the use of a 30mA RCD to protect the circuit also and I second this as will the majority of sparks on here.
Is your local supplementary bonding up to scratch?

__________________
Empty barrels make the most noise.

sm1thson · Posted: Wed Feb 07, 2007 2:53 pm Post Subject:

10mm will mean you dont have to do it again when you put a more powerfull shower in.

breca · Posted: Wed Feb 07, 2007 3:39 pm Post Subject:

Thanks for your help,what is a supplementary bonding?and why do i have to notify building control.
I shall only be laying the cables during the building stage of an en-suite,i sghall get a competant electrician to do the clever bits at the end with rcd,etc.

davy_owen_88 · Posted: Wed Feb 07, 2007 5:27 pm Post Subject:

breca wrote:

I shall only be laying the cables during the building stage of an en-suite,i sghall get a competant electrician to do the clever bits at the end with rcd,etc.

In that case don't worry about supplementary bonding and don't worry about building control - your electrician will sort all that for you.

You are very close to the limit of 6mm^2 cable. If I were you I'd put in 10mm^2 just for future proofing.

Davy

ricicle · Posted: Wed Feb 07, 2007 5:53 pm Post Subject:

davy_owen_88 wrote:

don't worry about building control - your electrician will sort all that for you.

Davy

So make sure he is registered and able to certify his work regarding Part P

__________________
Empty barrels make the most noise.

martynduerden · Posted: Fri Feb 09, 2007 1:11 am Post Subject:

All this Part p nonsense thank god i don't do houses ! although i do get worried by the occasional diy-er asking how to rewire a house!!