Installation of a new 9.8kW Mira Shower (long)

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A little warning, This post is going to be very long, but I'll try and get all the facts down, and try not to waffle too much.

My parents applied under a Local Government Scheme (mobility scheme) to have the bathroom converted to a wet room, with new walk-in shower, this entailed the complete removal of bath, wc, and toilet, and replacing with new this was performed by local contractors in the area (builders!).

My parents should have contact the Local Government agency as soon as they started to have issues with items, but they didn't they kept contacting the builder after the installation, had been completed, so this issues has gone under the radar for 14 months.

The problem, the shower keeps stopping (five times in 14 months), and blowing the 30A cartirdge fuse. I've only just learned this fact, after 14 months ago, the installation has been completed, and they've just been stating the shower's gone again, they call the builder, "fixes" it and goes away. Now that I've looked at the issue, I can see the problem. I'm not a qualified electrician, but I think I'm intelligent enough to view this, and have done some eletrical work, and then, arrange for qualfied electricians advice, and get it signed off correctly, to work out what's been done or not doen correctly.

The orignal shower was a 7kW, installed about 30 years ago.

The new shower installed is a Mira 9.8kW Advance ATL Flex (manual if anyone needs to read it!!!)

http://www.mirashowers.com/onlinecatalog/pdf/advance_90_98.pdf

This is the 30A switch it's currenty on.


I've not got involved with the Agency that completed the work, and I'm currently speaking to the Technical Officer that was responsible for signing off this work.

He told me, new wiring and RCBO had been fitted for the new shower, by the electrician, it's taken me four weeks, to convince the Technical Officer, that this is not true, evidenced by photos of the installation (see above), and I suspect the the Electrician didn't even visit under the stairs, and just hung the shower on existing cable in bathroom. After chasing the Certificate for Electrical Work, the certificate does not state this at all, it states, "extending the existing shower circuit to a new lower position" - I've yet to find out how this was done!


I've also measured with ruler the current cable, it measures about 10mm, so I beleive this is 2.5mm2 cable.

I've been concerned about the electrical work done by the contractors, and the Agency agreed to send a new electrican to re-view the job (after much discussion), clearly the Tedchnical Officer is out of his depth, and doesn't understand electrics.

So a new Electrician was scheduled to view the work.

My issues are as follows:-

1. Shower should be on a RCD/RCBO 45A. Not a 30A cartirdge fuse.

2. Cable from CU unit should be 4.5mm2 and not 2.5mm2.

It surprises me if you read the Shower Installation guide, it states 45A, RCD, and if you look at the signed off certificate it states 30A.

In the contract, it states the Contractor to install shower as per manufacturers instructions.

Am I correct on this?

Well, unfortunately, the shower blew again, when my father was covered in soap suds, and I got in the phone to the agency, and the only Electrician they could send round, was the original Electrician that did/didn't do the work, I wasn't really happy with this, but had no choice, I don't live in the area, and needed a fix.

So this was what got installed, despite the Technical Officer telling me, an RCBO was going to be installed:-


We've now got a 40A MCB on old wiring!

I know this is difficult to get a size but this is the wiring...



I would appreciate comments from an electrician.

I'm at the point, of just Complaing to the body, the Electrician is a member off. As I'm getting no joy with the Technical Officer.

(Sorry it's long.)
 
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That shower will draw over 40A, so no surprise that the 30A fuse kept blowing.

The certificate is junk, since they have test results for an RCD which doesn't exist, and the cable is stated as 6mm which it apparently isn't. Those insulation resistances of 999 are highly suspect, and although not impossible, circuit resistance of 0.61 and loop impedance of 0.32 is highly unlikely, particularly on a TNS supply.

For the original 30A fuse, the cable should have been at least 4mm (2.5mm can't be used with a 30A fuse).

If the cable is 4mm, then the 40A MCB does not comply. Even if the cable is 6mm, the new consumer unit is still wrong, since there is no RCD.

6mm cable could be used with that shower and a 45A MCB, but only if the cable was installed either surface clipped or plastered into the wall. Any other installation method would require a larger cable (10mm).

As a new circuit should have been installed (and a new CU has now been fitted), you should have received an electrical installation certificate, not the minor works cert which you have.
This is also notifiable work so you should also have another certificate stating it complies with building regulations.
 
thanks for the prompt reply.

Sorry, didn't make it clear, that certificate is for the first lot of work! (where they did nothing, other than hang shower on wall)

I've not yet seen the certificate for the new CU, they installed on Friday.

So, apart from certificates I get from Electrician, I should also get Certificate from Building Control?

I assume the council send me this?

So the following is wrong

1. Current Certificate is junk.
2. New shower circuit needs to be installed with CU and RCBO at 45A.
3. New Circuit cabling needs to be 6mm (possibly 10mm depending on route under floor boards, insultation etc, cable clips etc)
4. Also another Certificate stating in Compiles with Building Regs.

So out of 10, how do you score this installation?
 
You might find the Local Building Control Office helpful in this matter. Some of them now are very keen to take out of business people who do this type of shoddy work.
 
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0 out of ten!!
which cable are we looking at on the picture??its not the one thats not painted is it?
 
The hot cable !

It doesn't even look like 2.5mm cable, but it might be.

You need to get this sorted ASAP.
 
I would also be concerned about the size of the cable feeding that CU for the shower.

Also nearly 43 amps on a 6mm cable?
 

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