Electric Shower help

Toaster10

Hi, looking for some advice on our shower situation if possible please.

We moved house last year and the house had a 9.5kw Mira electric shower. We subsequently had a lot of work done on the house and a lot of the house was rewired and a new fuse box fitted.

At this point, the shower stopped working and the electrician said that it was because it was a 9.5kw shower but the cable wasn’t big enough to support it, so the new fuse box doesn’t allow it to continue to work. He didn’t offer to fix it.

So, we haven’t had a shower for months and now just really need it fixed!

Husband has opened up the shower and measure the cable and says it’s 5mm so therefore can only support a 7.5kw shower.

As it’s a Mira shower that’s currently there, we want to replace with a Mira to keep things simple.

However, for some reason, the Mira 7.5kw showers seem to be more expensive than more powerful ones. I’ve found one I can get for £113.

My dilemma is, will a 7.5kw shower be rubbish? My alternative seems to be replacing the cable that runs from the fusebox with a bigger cable. If we do this, am I right in thinking we shouldn’t even need a new shower as the existing one would then work?

We need about 10m of cable, so about £40 for that’s however, I’m not sure how comfortable my husband would be doing that himself.

We are on a tight budget so looking for the easiest / cheapest solution.

Any help/guidance appreciated!

Toaster10

Edited to add - £113 for the shower is a decent price. But there’s only one place selling one at that price, everywhere else is at least £180

coffeehound

A 7.5 shower would be fine in the warm/mild weather but will run more slowly in winter when the mains water gets cold. Best to get the thicker cable installed and fingers crossed the 9.5 shower still works.

Edited to add: the electrician will have put in a lower current value circuit breaker to suit the 5mm cable so you will need another one of those, too.

JohnBartley

Don't use electric showers... they're horrible! And put the fear of god in me!

Toaster10

Thank you, coffeehound.

How complex a job is it to change this cable ourselves? Husband has been up in loft and located the cable but I’m not sure he’s that confident about doing this himself.

Toaster10

John Bartley, I know, by choice I would have a mixer shower instead - but that’s just outwith our reach at the moment Trying to make do with what we have but there just seems to be a problem at every turn

googler

Toaster10 wrote: »

Thank you, coffeehound.

How complex a job is it to change this cable ourselves? Husband has been up in loft and located the cable but I’m not sure he’s that confident about doing this himself.

Depends on the route the cable takes, and whether or not the installers have left the cable loose in void spaces such that you can use the existing to pull the new through the same spaces.

In my/our case, lots of our cables run through studwork and behind plasterboard, and have clearly been sandwiched between same, such that even a determined tug produces little or no movement.

More destructive option is to remove plasterboard at such points, but in your case, this will depend on route of cable and construction type

Toaster10

It comes from the fusebox, which is above our front door and runs through the loft about 6m and then comes straight down into the bathroom, behind the tiled bathroom wall.

I haven’t been up there myself though, so will show your post to husband and see what he reckons.

Thanks again ��

Carrot007

Electrics, plumbing and all that sort of thing are very easy (others will say otherwise).


However they are compounded by the pain of having to do things in impossible places often.


Repalceing a cable is simple and TBF I would never want a electric shower again. Far too slow and cold in winter. Gas powered by combi or tank are much better options. As are presumably those powerd "heads" only things that are popular elsewhere but I do not know it they are up to regs.


Of course if you have a old old consumer unit not on a RCD and are not competent then do not do it.

Toaster10

I would prefer a mixer shower but I really just need the easiest, cheapest solution at the moment.

The only place the shower can go is at the opposite end from the bath taps (where the electric shower currently is). If it could go at the bath taps end I’d be tempted to consider getting a mixer shower put in there, but I can’t see that there is any easy, non-messy way to get pipes to the other end of my bath.

The bathroom is also all tiled and I don’t want to be punching through tiles cos I’m not in a position to re-do the whole bathroom at the moment.

The fuse box etc is brand new and apparently everything is now up to date and safe etc......except the shower. Kind of wish the electricians that did this had fixed the shower but that’s a whole other story.....

Owain_Moneysaver

Toaster10 wrote: »

At this point, the shower stopped working and the electrician said that it was because it was a 9.5kw shower but the cable wasn’t big enough to support it, so the new fuse box doesn’t allow it to continue to work. He didn’t offer to fix it.

Husband has opened up the shower and measure the cable and says it’s 5mm so therefore can only support a 7.5kw shower.

The consumer unit doesn't know what cable size is connected, so there's no way it can decide whether to 'allow' the shower to work or not. If the cable was undersized the electrician who changed the consumer unit should have told you, and not reconnected it.

And there is no such thing as 5mm cable, so I don't know how your husband has measured that.

6mm cable is sufficient for an 9.5kW shower at 230V depending on how the cable is run (clipped direct to wall surface, no insulation, 10 metre length). If the cable is on a plasterboard ceiling with >100mm insulation you'd need 10mm and in an insulated stud wall not touching plasterboard 16mm which would be expensive and very difficult to dress neatly inside the terminals.

Your electrician will need to do design calculations for your installation. Anything less is guesswork.

A new cable doesn't have to follow the route of the old. It is also permissible to run the cable on the surface using trunking or conduit if the shower manufacturer says this is suitable, so tiling need not be dug out.