I have had a new shower

[Heleno]

I have had a new shower that is 10.5kw. My old shower was only 7.5kw and so the instructions recommend that i have a 45amp fuse. I know the wire is thick enough (12mm), but i was wondering how difficult it is to change the fuse to a 45amp. I know this is vague...but, im living on my own, and not very good when it comes to stuff like this, i just dont want to get an electrician to do it if its an easy job.
Thanks
Helen

 

[dingbat]

It is not an easy job.
You will almost certainly need to upgrade the cable and most shower manufacturers require that the circuit is protected by a residual current device (RCD)
There is also the question of earthing and bonding.
And Part P of the Building Regulations.

Sorry, but you do need an electrician for this and in my experience it generally costs somewhat more than the purchase price of the shower itself.

 

[ban-all-sheds]

I know the wire is thick enough (12mm)

There is no such size as "12mm".

Cable sizes are the cross-sectional area of the main conductors, nothing to do with any other dimension of the cable.

The sizes of twin & earth are:

1.0mm²
1.5mm²
2.5mm²
4mm² (what you probably have right now)
6mm² (what you might have right now)
10mm² (what you don't have right now, and you need for your 10.5kW shower)
16mm²

i was wondering how difficult it is to change the fuse to a 45amp.

It depends what type of fusebox you have. Worst case, I'm sorry to have to tell you, is that it may not be possible at all...

 

[Adam_151]

snippet from 'for reference' :

Judging what cable size you have:

1mm² CSA T&E has overall dimensions of 7.8mm x 4.25mm
1.5mm² CSA T&E has overall dimensions of 8.2mm x 5mm
2.5mm² CSA T&E has overall dimensions of 10.3mm x 6mm
4mm² CSA T&E has overall dimensions of 11.9mm x 6.25mm
6mm² CSA T&E has overall dimensions of 13.5mm x 7mm
10mm² CSAT&E has overall dimensions of 17.1mm x 10mm
16mm² CSA T&E has overall dimensions of 19.4mm x 10mm

Source: http://www.tlc-direct.co.uk

 

[Steve]

you really ought to use a 50A MCB / fuse, as the 45A one will run hot.

Yes, you need 10mm² cable, without a doubt. Anything less would also run hot. This is difficult stuff to work with, so if you aren't confident, get an electrician to connect it up.

Though as said before, you may need a new consumer unit (additional or renew existing) - to accomodate the 50A MCB/fuse.