Hi all, I have a Creda Advantage 10.5kw electric shower which is fed by a 10.5mm t&e cable. It is RCD protected and is fed via a 40Amp MCB. The shower was protected by a 45Amp isolator switch which I have found was bought from wickes: http://www.wickes.co.uk/invt/204947 A few days ago, I went to switch the isolator on and got nothing from it. I checked the MCB and RCD and both were switched on. On testing the isolator, I was getting 230V at the supply side of the switch. On switching the isolator on though, nothing was being given on the load side of the isolator. I bought a new isolator switch and on opening the old one up again, I noticed that the plastic sheathing on the load live cable was black and crumbly. I cut and stripped this back until I got to untarred copper. My question is why would this happen? I'm guessing the the cable had not been stripped back far enough by the electrician who fitted it and it was touching the copper internals of the isolator switch. When the current was flowing and the cable was hot, I'm guessing that this had burnt the sheathing? I also remember that when the electrician was fitting the isolator, I did ask if it should be of a higher amperage as the max current flowing may hit 45.6 Amps but he explained that the mcb would cut the current before the isolator was affected and so it was fine. - Is it fine or should the isolator be of a higher amperage? Many thanks.