Electric Shower Cable, correct size?

[sparxy]

Hi all,

Had an electrician fit me a new shower cable. Since they've fitted it, when the shower is in use it heats up quite dramatically.

The cable is 6mm2 T+E, the shower is a 10.8kW (9.9kW at 230v) unit. The cable is currently in free air running as they are returning to run wiring to the garage and an outside light, but they mentioned running it in trunking up the wall. It has a 45A rated breaker.

From my little research on the subject, this seems the wrong cable, especially if they were to run it in trunking rather than bury in the wall.

Is this the correct size of cable?

 

[oldbutnotdead]

From memory, 6mm will do 45A clipped direct and not going through insulation. But you don't mention cable length or what else the cable goes through (or will be going through when you've decorated).

 

[EFLImpudence]

It should be fine in free air - or clipped direct or buried in masonry.

It won't be when in trunking.


It shouldn't get too hot - over 70°C.
It depends what you mean by quite dramatically, I suppose.

 

[sparxy]

From memory, 6mm will do 45A clipped direct and not going through insulation. But you don't mention cable length or what else the cable goes through (or will be going through when you've decorated).

It goes through the ceiling/floor (i'm not sure if there is any insulation there), up the landing wall to the switch and then through the wall to the shower. Maximum of a 8m run from CU-Switch and then < 1M to shower.

When you say buried in masonry, is it acceptable for it to be dug into the wall (through whatever layer of plaster and some brick), and then filled in on top?

 

[EFLImpudence]

When you say buried in masonry, is it acceptable for it to be dug into the wall (through whatever layer of plaster and some brick), and then filled in on top?

Yes.

 

[EFLImpudence]

Are you positive it is 6mm²?

 

[sparxy]

Are you positive it is 6mm²?

Embossed into the grey insulation (difficult to read as not at eye level), 6mm² and some more text/numbers.

 

[EFLImpudence]

Ok. It should be ok - with the above limitations.

 

[oldbutnotdead]

That length run chased into the wall and in free air or clipped in the ceiling will be fine with 6mm. You may find (if you haven't experienced electric showers before) that the flow rate at adequate temperature becomes a bit lame in the winter. While the place is in chaos it might be worth considering 10mm (so you can upgrade to a 12kw unit if you do find it a bit poor) (typical gas combi heat exchanger delivers 30kw in comparison).