shower wiring

[m_coops]

I am putting in a new electric shower. The current wiring is 10mm (sq.) wiring back to a re-wirable fuse of 30A.
I am looking at replacing the current shower (8KW) with an 8.5 or 9 kW. Both shower installation guides (I haven't bought it yet - just checking on the internet) specify a cartridge fuse of rating 45A. Can I just replace my re-wirable fuse (30A) with a cartridge type (45A) and are there any other implications ? Help appreciated

 

[ban-all-sheds]

You would be much better off installing a separate shower CU, as I'll bet your existing installation does not have an RCD.

You are aware, I take it, of your legal obligation to notify LABC about the shower replacement before you start?

 

[Steve]

You have to have a 45A MCB and an RCD is also recommended for shower circuits, as ban has pointed out.

OOI, how do you know the current MCB is 10mm²? I wouldn't think anyone would put a 10mm² cable on a 30A fuse, unless it is a very long run. Sure its not 6mm²? The difference is crucial.