hi looking for a little advice on electric showers ,i have a mira 9.8 sport fitted but is on its last legs and while looking for a new one have been offered a 10.8 kw for the same price as 9.8 i have a 40 amp fuse fitted i have read i need to change that to 45 but have seen no mention of the type of cable required i have 10mm cable twin core and earth is this ok or do i need a rewire . cheers for any help