Another electric shower question

[waynes]

Good morning all,
sorry but I've got another electric shower question.
First I will explain our current setup.
We have an old Mira electric shower, its connected to a switch outside the shower room which looks to be a kitchen cooker type switch, this is then run directly to the consumer unit by what looks to me to be 6mm cable, it is run in 2m of stud wall then 8m of ceiling void. It is run back to a plug in 16a fuse, no problems with it except you have a warm trickle or nothing.

The comsumer unit is an old wylex unit which has been converted to plug in fuses, there is no rcd.

What is going to be the best way to upgrade the shower to something useful?
We have an unused 32a plug in fuse and so could swap it for the 16a(inc the base part) any problems with doing that? that should allow me to put a 7.5kw shower and hopefully that would be adequete or would it be worth purchasing a 40a set? or is that too high for 6mm with that run?

What about the rcd side of things? outside has a set of rcd protected outside sockets so no worries there.
Can you but rcd switches for the shower? or plug wylex rcd units?
Or is it ok too continue without rcd protection as it is currently and has been for the last 40 years (looking at the bathroom decor!)


Thanks for all your advise in advance

 

[Adam_151]

16A is approx 4kw.... either your shower is a *very* pathetic trickle becuase one of the heaters in the shower unit is open circuit, or its a 6kw/7kw unit and that MCB is knackered

Is it 6mm², are you sure about that? if its as old as you say its not beyond possibility that its a 4mm²!

How is the cable run in the stud wall? through any insulation? (and if so, is it in the middle of it, or pressed against the plasterboard?)

ditto with the ceiling void, how is it run in there?

Its possible you may be able to install a 7kw shower, but that would still be pathetic, it is my opinion that you'd be better off biting the bullet and installing 10mm² cabling from either a separate shower CU, or a new CU

 

[waynes]

The shower is a very pathetic trickle if you want any warmth to it!
The stud wall has no insulation and neither does the ceiling void, clipped in both (for as far as I can see)
The Mcb I belive is a recent addition, it was using wireable fuses recently.
Need to get new bsatteries for my Measuring stick to be 100% sure on cable size as I have no spare 4 or 6mm about to compare agaisnt.

You would suggest I get a 10mm cable run in? would you also suggest I get a seperate cu for the shower so it can have rcd protection? I just want to check as money is very tight on this and it starts to get expensive that way.

As usaul I want the best, safest and cheapist solution!

But really I am happy to a useable shower(its not currently) that is safe and not going to burn ther house down. Are 7kw showers that bad? how vital is the rcd protection?

I know I am not qualified to answer these questions otherwise I wouldnt be asking so all comments are appreciated and I am happy to consider most solutions but I need to keep it in budget or it dosnt happen

 

[waynes]

Anyone else able to offer any advice?

 

[ban-all-sheds]

You would suggest I get a 10mm cable run in? would you also suggest I get a seperate cu for the shower so it can have rcd protection?

You don't need a separate CU just to get RCD protection - you could just install a standalone RCD, but you probably won't be able to get a large enough breaker to support a decent shower.

Are 7kw showers that bad?

Pretty poor, particularly at this time of year.

how vital is the rcd protection?

Less vital than on sockets supplying portable equipment outside, and you haven't got it on those either, but on balance a good idea.

 

[waynes]

how vital is the rcd protection?

Less vital than on sockets supplying portable equipment outside, and you haven't got it on those either, but on balance a good idea.[/quote]

Luckily we have a double socket with rcd protection outside, again a recent install from the look of things.

Ok so a 10mm cable run in to to consumer unit from the shower and aim for a 8.5kw shower.

Thanks all

 

[Adam_151]

Sorry I didn't come back to this one earlier... but to comment on the latest post....

Chances are your Wylex standard can't handle a breaker in excess of 32A (if the main switch is rated at only 60A then this will almost certianly be the case)

32A x 240v = 7.5kwish max shower

 

[ban-all-sheds]

8.5kW is still feeble.

And it's 35-37A - can your old CU cope with that? Depending on the rating of the main switch it may be limited to a maximum of 30A for any single load...

[EDIT] Doh! [/EDIT]

 

[waynes]

where would i find the main switches rating?

cant see anything written on it, ay just be blind tho...

 

[Adam_151]

Any chance of a picture?