I'm fitting a 10.5kw Electric shower but unsure of MCB

[jbakerboy]

Hi all, I currently have a 8.5kw Triton Electric Shower but it's playing up, so i'm changing it for a 10.5kw Aqualisa.

Now i'm no expert but like to think I have my head screwed on.

The problem I have is that I know for a 10.5kw Electric shower I need 10.0mm T&E and I currently have 6.0mm from consumer unit to 45a switch, then (heres the interesting bit) from the 45a switch is 6.0mm but when I took the front off the shower then Hey Presto 10.00mm T&E, which leads me to believe theres some dodgy going ons in the loft.

Anyway i,m going to replace the whole run in 10.0mm but its the connection to the consumer unit i'm not sure of.

The current shower is a 8.5kw and it goes to a 45amp switch then to the consumer unit on a 40Amp RCD. It is about a 10Mtr run, 4 mtrs in my loft which has 6" insulation and is boarded, then comes down into the airing cupboard and is clipped to the wall (3mtrs) then goes underfloor and drops to consumer unit (3mtrs).

Should it be on a 40Amp RCD or on the MCB side of the unit and also is 40Amp enough? Or should I install the shower and if it trips upgrade RCD?

As I said earlier I'm not a profesional but I am Keen

Any help in this matter would be greatfully appreciated!

 

[EFLImpudence]

10.5kW @ 240V is 43.75A so you will have to keep the 45A mcb.

It should be on the RCD side of the CU.

Actually 6mm² cable would be alright but it must not run through any thermal insulation or conduit.

Even 10mm² could be too small through or covered by thermal insulation so make sure the cable is free of any thermal insulation.

 

[Iggifer]

10.5kW @ 240V is 43.75A so you will have to keep the 45A mcb.

I don't think he has a 45a mcb, I think he was referring to a 45a rated pull cord. Sounds like it's on a 40a mcb (OP called it an RCD)

 

[jbakerboy]

Hi, dont have a pull cord but a 45Amp switch in airing cupboard. its currently on a 40amp breaker on consumer unit.

Thanks for replies.

James

 

[Iggifer]

In that case the MCB will need changing to a 45a

 

[EFLImpudence]

Yes, misread - as Iggifer says

 

[jbakerboy]

As I haven't checked to see if 45A is available as looking at some posts they say its not available anymore, if I need 45A (and it's not available) should I stick with 40 or upgrade to 50?

Again Many thanks to all, tis much appreciated!

James

 

[EFLImpudence]

You will have to go for 50A.

Then you will have to rewire with 10mm² on the whole run and a 50A switch.

 

[jbakerboy]

I intend on running a whole new 10mm T&E, and aslong as i'm not causing any danger I will upgrade the MCB to 50A.

Thanks

 

[Scoby_Beasley]

Hi, dont have a pull cord but a 45Amp switch in airing cupboard. its currently on a 40amp breaker on consumer unit.

The switch must be readily accessible but out of reach of a person using a fixed bath or shower....

Not a big fan of "switches in airing cupboards" myself for the above reason.