Electric shower cable question

DocKate

I need to replace an electric shower. One electrician took one look at the shower and said that we would need to replace the cable as well at a cost of around £750, as apparently, it is currently a 6mm cable to a 10.5 kw shower (it was installed when we moved in). Another electrician has said that we could install a 8.5 kw shower, as that would work on any size of cable, and yet another one has said we could install a 7.5 kw shower with a 6mm cable. We wouldn't be doing it ourselves but need to know whether we are being taken for a ride by the first, being fobbed off by the other who doesn't know what he is talking about, or being offered a viable solution by the third. Any electricians out there who could give me some advice?

jk0

DocKate wrote: »

I need to replace an electric shower. One electrician took one look at the shower and said that we would need to replace the cable as well at a cost of around £750, as apparently, it is currently a 6mm cable to a 10.5 kw shower (it was installed when we moved in). Another electrician has said that we could install a 8.5 kw shower, as that would work on any size of cable, and yet another one has said we could install a 7.5 kw shower with a 6mm cable. We wouldn't be doing it ourselves but need to know whether we are being taken for a ride by the first, being fobbed off by the other who doesn't know what he is talking about, or being offered a viable solution by the third. Any electricians out there who could give me some advice?

7.5kw or 8.5kw would be fine with 6mm cable IMHO.

bris

10mm is the right cable for a 10.5 KW shower. You will get away with a 6mm for the 8.5 but its recommenced to up the cable to 10mm.


No decent electrician will fit a 10.5kw shower to your 6mm cable.


Get a 10mm cable for 9.5 or 10.5.


8.5kw showers are pretty poor tbh.


£750 seems expensive to replace a cable though, get other quotes.

knightstyle

Yes, you will need to replace the cable but you can keep the cost down by buying it yourself and replacing the existing cable, then get an electrician to do the connecting and give you a certificate.
costs £4 to £5 a metre.

Risteard

knightstyle wrote: »

Yes, you will need to replace the cable but you can keep the cost down by buying it yourself and replacing the existing cable, then get an electrician to do the connecting and give you a certificate.
costs £4 to £5 a metre.

No you can't. No Electrician will connect up a cable you've wired in not under their supervision.

Owain_Moneysaver

8.5 kW on 6mm is a bit borderline - it depends on the cable length and mounting method.

£750 to replace a cable sounds like a lot - but it depends where it's run and how difficult it is to access and make good.

If you have a suitable hot water system a conventional (non electric) shower might be a lot cheaper than paying that price to change the cable.

Mr.Generous

It really depends where the cable run is, If the mains board is in a garage and the single shower cable is attached direct to brick, up through a redundant airing cupboard (surface clipped) and into the back of the shower then you will be ok, 6mm can carry 47amps if its not enclosed or under insulation - unlikely I know.

If its in conduit or in the wall it shouldn't be used for a 9.5kw so you are stuck with an 8.5kw or a new cable. £700 is very high cost for the job I think.

Apodemus

Risteard wrote: »

No you can't. No Electrician will connect up a cable you've wired in not under their supervision.

I appreciate that Risteard is this forum’s “voice of reason” or “harbinger of doom” for all things relating to electricity and DIY, but there are plenty of electricians who would be only too happy to let the householder do all the wall-chasing and fabric work of routing a new cable through the property, leaving both ends disconnected with suitable tail lengths for them. Since you would be discussing this with them, this would of course come under the description of being “under their supervision” and you would use their specification of cable.

Risteard

Owain_Moneysaver wrote: »

8.5 kW on 6mm is a bit borderline - it depends on the cable length and mounting method.

For a typical clipped direct installation there is nothing borderline about it.

baldelectrician

Does the existing install have an RCD?

Does the dear quote include a consumer unit replacement?

Owain_Moneysaver

Risteard wrote: »

For a typical clipped direct installation there is nothing borderline about it.

Is "clipped direct" typical, though? I don't have any clipped direct wiring in my home; it's buried in a masonry wall, in steel conduit, or in trunking with a grouping factor to be applied.

Many people will have cables inside insulated plasterboard walls or ceilings.

Never mind 10mm, I have a 16mm cooker circuit. Don't know why, but that stuff's a pain to dress nicely in a CU.