Electric Shower questions

[wedge69]

Hi guys and gals, couple of questions I hope one of you will be kind enough to answer.

We currently have a (broken) 8.5kW Mira Sport. It's connected with 6mm cable and a 40Amp MCB. The consumer unit is RCD protected.

As mentioned, the shower is currently broken, and we are going to get the bathroom redone.

Am I right in thinking that the wiring/MCB setup can only support a 8.5kW shower at max, and if I went to anything else (even only up to 9kW) I would need a qualified electrician (as it involves work in the batrhoom) to upgrade the cable?

What (if any) certification should I receive for a cable upgrade?

How much would it cost? (If I can ask that!)

Thanks

 

[ban-all-sheds]

As mentioned, the shower is currently broken, and we are going to get the bathroom redone.

You might as well go to 10mm² cable and a 10.5kW shower.

Am I right in thinking that the wiring/MCB setup can only support a 8.5kW shower at max, and if I went to anything else (even only up to 9kW) I would need a qualified electrician (as it involves work in the batrhoom) to upgrade the cable?

40 x 230 = 9200
40 x 240 = 9600 (most showers use 240V for their headline rating)

6mm² cable is probably OK for 40A - do you know how long it is, and whether it runs through thermal insulation anywhere?

What (if any) certification should I receive for a cable upgrade?

An EIC and a Building Regulations certificate.

How much would it cost? (If I can ask that!)

 

[wedge69]

As mentioned, the shower is currently broken, and we are going to get the bathroom redone.

You might as well go to 10mm² cable and a 10.5kW shower.

Yeah, that seems to make the most sense.

Am I right in thinking that the wiring/MCB setup can only support a 8.5kW shower at max, and if I went to anything else (even only up to 9kW) I would need a qualified electrician (as it involves work in the batrhoom) to upgrade the cable?

40 x 230 = 9200
40 x 240 = 9600 (most showers use 240V for their headline rating)

6mm² cable is probably OK for 40A - do you know how long it is, and whether it runs through thermal insulation anywhere?

From the CU at the front of the house, up unto the loft and down to the bathroom. I'm awful at estimating, but somewhere around 15 m? When I've been up in the loft I can see the cable comes out from the shower switch, laid over the top of a bit of insulation for a couple of m and then disapears down into the cavity between the walls, if you see what I mean.

What (if any) certification should I receive for a cable upgrade?

An EIC and a Building Regulations certificate.

Are there examples of these anywhere? Just so I know what to look for.