Mira Sport Max 10.8kW Shower Installation

I've bought a new Mira Sport Max 10.8kW electric shower to replace my existing mira sport shower. I'm not sure of the model or the kW but I don't think that is important.

The length of cable from the CU to the shower via a new 45A double pole switch is approx 12 meters. The 45A double pole switch will be installed on the wall outside the bathroom door due to the smallness of the room so it cannot be reached by anyone in the shower. I intend to use the existing cabling if it is 16mm. If it is only 10mm will that suffice or should I replace it with 16mm?

I'm fitting a 45A MCB (currently 30A) in the CU for the sole use of the shower circuit and installing a RCD between the CU and shower close to the CU. What size RCD should I install?

I think your making some assumptions, that you shouldn't.

A 30 amp existing MCB may well be 6mm, but it's unlikely to be 16mm.

You haven't mentioned how the new cable will be run- surface / void, clipped, conduit, trunking, in insulation etc.

You haven't mentioned testing or going for LBC approval for cert / Part P conformity.

I would suggest you check out the DIYnot wiki and in the UK electrics section cross ref the cable physical sizes table with what you have to firm up the existing cable size and it's potential for reuse.

As for the rcd requirements, asking suggests you haven't got a clue and maybe it would be wiser to seek a sparks to do the work.

http://www.tlc-direct.co.uk/Products/CPR016P.html

You haven't mentioned the type of board that exists, it might take an RCBO which replaces a MCB and has the plus of RCD functionality.

http://www.tlc-direct.co.uk/Main_Index/Consumer_Units_Index/index.html


Please remember that showers / water and power = death if installed incorrectly, and how would you feel if someone had a serious accident due to the work (unknowingly) being unsafe ?

I've been onto a website tlc-direct.co.uk and used their voltage drop calculator to determine the cable size and I took note of the cable run requirements and it came out with a 16mm requirement. I just wanted some confirmation.

I intend to get it tested by a qualified electrician when I've finished and before it is used. I'm not completely stupid.

As for the RCD I would put a 45A one in but was just asking for some help/confirmation.

biasnetworks said:

I intend to get it tested by a qualified electrician when I've finished and before it is used. I'm not completely stupid.

As for the RCD I would put a 45A one in but was just asking for some help/confirmation.

Click to expand...

You need to get the electrician involved before you start.
He won't sign off/check anyone elses wiring after you've finished.

Good luck finding a 45A RCD.

OK I'll get an electricain involved. Having had a quick look at RCD's no 45A ones either 60A or 40A. Which one then?

What make is the existing CU, could it support a RCBO ?

(although I have asked you for that info already).

As for your comment about "not being that stupid"- Well we aren't either. Why not get a spark, agree a cable size and route, you do the donkey work and he hits you for a few hours of commissioning and test time.

You get the job at lower cost
You get a safe installation
You get a cert
You get the comfort of knowing the work is to regs

Please accept that the advise is intended to prevent danger, and to comply with the legal aspects of our industry.

You also need to understand that 1000's of peeps post for info on here, and have absolutely no intention of employing someone to do the work.

Your "I'll get someone in when the work is done" is nearly as common as "my electrician is on holiday"

Chri5

It's a Wylex which won't take RCBO's. Having had a good look at it's only rated to 60A. however the MCB's are rated as follows

Circuit 1 Lights 16A
Circuit 2 Heating 6A
Circuit 3 Immersion Heater 16A (switched off unless CH fails)
Circuit 4 Downstairs Sockets 32A
Circuit 5 Upstairs Sockets 32A
Circuit 6 Shower 32A (No RCD)
Circuit 7 Outside Lights 16A
Circuit 8 Spare 6A

I'm going to take your advice and get an electrician in to discuss the work agree how much I can do (the donkey work as you put it ) and get him to finish off, test and certify.

Looking at the MCB rating they total 150A not including the spare. Does this mean that I am in danger of blowing the main fuse?

I have a Wylex 60A fused switch between the Meter and the CU.

Do I need to get my electric supplier involved to upgrade the supply?

Should I replace the current CU with something like a MK Sentry
17th Edition Insulated Flexible Dual RCD Consumer Unit 100A Main Switch
1x 80A 30mA RCD + 1 x 63A 30mA RCD?

If the answer is yes then this new shower now looks like and expensive job!!