8.5kw Shower on a 6mm cable

Firstly, loose connections will not always trip RCDs, the fishy smell and sound are arcing are present long before that. Loose connections in pullcords are fairly common, loose connections in shower units slightly less so. It's usually the neutral that burns as well. You might be be lucky and have enough length, otherwise part of that little circuit is in for a rewire. 6mm cable, depending on the run, is likely to be fine for an 8.5kW shower. Rcd protection is helpful, but bonding and cross bonding are far more important. And a 30a breaker, fuse wire wouldn't pop for overload either as it's unlikely to be overloading long enough. Certainly not a diy job though. Danny

You have had/have a loose connection somewhere. Get a competent electrician to come a give you a diagnosis and remedy. The MCB ( Circuit breaker) would not have tripped as it trips on overload. Doesn't sound if you have RCD protection, ask the electrician. Please don't attempt a repair as its safety first, leave it to the pro's.

6mm is slightly under for an 8.5kw shower. However 30amp is adequate for the cable but ought to of tripped for that shower. I would suggest upgrading your fuse board to something that has RCD protection for the circuit and shower. This would be mandatory if the shower was new anyway. You say 2 years? Is the shower new or the whole circuit? If the shower is new then sounds like the installation could of been at fault. If the circuit is new then it shouldn't of been installed in the first place on the old board. Get an electrician to replace the shower to something under 8kw. Get them to quote for a new fuse board whilst you are at it!