Replacing 7.5kw shower with 8.5kw

[danoid]

I'm after some advice, I will not be doing this myself, but want to know what the likely outcome will be.

Moved into a 1993 built house, which had a Mira Sport electric shower from 1993 and it's died so needs replacing.

The current shower is 7.5kw and has a thick flat cable going into the shower and it's Black, Red & Earth.

Looking at replacement showers I've seen one on screwfix which is 8.5kw for only around £50 and it's a Triton and has good reviews, the problem is 7.5kw now seem to be expensive and hard to come by for the same price.

I've been googling and apprantely all that may need replacing is the MCB in our consumer unit (do they have numbers on it, just in case the current one is adequate?)

I've seen some others going about replacing the wiring, but that will be silly money compared, but how do I know if the current cabling is up to the job already - please keep this in simple terms - do I just measure the width of the red+black cables from left to right, or do I need to measure the width of the entire cable coming from behind the tiles?

Or, could I just buy an 8.5kw and it'll work, so awkward as to why 7.5kw isn't really made anymore.

 

[ricicle]

What rating is the existing fuse/circuit breaker ?
If it is a fuse, what type of board is it ?
Is there 30mA RCD protection already in place for the shower circuit ?

A guide to sizing cables (physically) can be found here

 

[danoid]

Good question, no idea to any of them.

BTW when I say MGB it may be RCD haha.

Shall I get a picture of my consumer unit?

 

[stillp]

Shall I get a picture of my consumer unit?

Good plan. If you have a decent camera, a close-up of the cable might be helpful too.

 

[danoid]

For the wiring is that a photo of the wiring into the electric shower

 

[stillp]

Yes, showing the conductors if you can. Isolate first!

 

[riveralt]

Mira still make and sell at least two 7.5kw electric showers.

 

[danoid]

Cool, will get pictures a bit later (still at work) and upload in full resolution.

I was looking at a site about a Mira 7.5 and it said not to use in low gravity, from what I can tell the old shower just gets it's feed from the water tank in the loft and turning the old one on briefly seemed ample pressure, so not sure whats that means tbh.

The old shower had a split on the heater bit by the metal weld, which is why a new one is required as the part on it's own is near £90, so might aswell get a new one

 

[ban-all-sheds]

so awkward as to why 7.5kw isn't really made anymore.

Because most people find them woefully inadequate. Even a 10.5kW is rather poor in the winter.

 

[canduit]

so awkward as to why 7.5kw isn't really made anymore.

Because most people find them woefully inadequate. Even a 10.5kW is rather poor in the winter.

That is down to personal choice. I've got a 9.5 kw and it suits our needs; the type of shower head makes a noticeable difference too. But I will admit that it will never match a combi boiler shower!

 

[danoid]

Hello, sorry took so long.

1st picture
http://danstyan.co.uk/shower/IMG_2653.JPG
40a, thats good isn't it?

2nd picture
http://danstyan.co.uk/shower/IMG_2680.JPG - Don't worry I isolated the electric first and as an estimate of wire size thats my finger

 

[EFLImpudence]

Well, assuming the circuit is satisfactory and compliant now then you can change to an 8.5kW shower.
The cable does look a bit small and smaller than those in the shower but it may be alright. How big is your finger?

However, the manufacturer's instructions will call for RCD protection (which you don't have at present) and an electrician should be unwilling to fit a new shower without.
You could just fit an RCD external to the consumer unit.

Anyway an electrician will be able to determine all of this when there.

 

[danoid]

My finger is 2cm width (learn something new everyday)

Typcial about rcd protection, nothing in england is ever straight forward how much does that cost roughly?

Might aswell fork a little more for a 7.5kw and not bother with having to get anything else changed

 

[danoid]

Forgot to upload the other picture.

http://danstyan.co.uk/shower/IMG_2652.JPG

I noticed the ones that are under "RCD protection" have a different logo (same as the shower breaker) so does that mean it is RCD protected?

 

[riveralt]

Forgot to upload the other picture.

http://danstyan.co.uk/shower/IMG_2652.JPG

I noticed the ones that are under "RCD protection" have a different logo (same as the shower breaker) so does that mean it is RCD protected?

Provided your cable is the right size then your electrician would just need to move the 40A shower MCB and associated cables over to the RCD side of the Consumer Unit then your shower will be RCD protected.
Don't you do it yourself unless you are confident and competent to work in an environment that may have live parts.