Shower keeps tripping out - 4 weeks after fitting!

I have a strange situation where a newly fitted 10.5W shower keeps tripping the RCD switches, it statred last night 4 weeks after it was first used. I spoke to an electrician mate who works next door and he said that the shower is too big for the circuit (makes sense) but why would it take 4 weeks to figure that out?!?

The only thing that has changed is that we had a door fitted on the bathroom yesterday and my wife had a shower with the door closed and in such a small bathroom she said it was like a steamroom - could this have affected the shower in any way? Please forgive me but i'm not an electrician and any help or advice would be appreciated.

Regardless of whether the shower is too powerful for the circuit, that will not be the reason the RCD is tripping. The RCD detects an inbalance between phase and neutral which means that some of the current flowing through the phase or neutral conductors are going via the earth conductor somewhere. This is probably due to a loose connection at either the shower or the isolator. IF you feel confident that you can remedy this situation yourself then isolate the power at the consumer unit and check the connections for loose conductors, burnt/scorched insulation or anything else out of the ordinary.

If you do not feel confident doing this, then call an electrician.

Regarding the 'steamroom' problem, you need to get an extractor fan fitted, and open a window.

What size MCB is the shower connected to?

Davy

If it is an MCB tripping, rather than an RCD, it may have been damaged by being overloaded, and has now given up the unequal struggle.

MCBs are selected considering the cable size, length and how it is installed as well as the load, so just replacing one with a different rating is not a safe option.

Right I had a quick (5 hours) look at this last night. I've figured out that the live cables in the isolation box had burnt through the earth cable thus causing the tripping out problem. I couldn't work out if this was a new problem or one that was existing before I changed the shower as I had some hot/cold issues with the old one.

I rewired it back up and the shower works fine but I went to my local DIY shop to figure out which type of wire I have and matched it up to a 6mm cable which I know isn't good for a 10.5kw shower!! I have an electrician coming around tomorrow to decide on the best option, re-cable or new shower. Also, how do I figure out what level of protection my consumer unit has?