Electric Shower trips fuse

[Andy_E]

I'm considering just calling out a qualified electrician but wondered if anyone could give me some things I might like to check before doing this. Here is the situation. The electric shower in the bathroom trips the switch on the fuse box whenever I turn on the power supply to run it. It has been wired onto its own switch on the consumer unit. It then runs to a switch fitted to the exterior bathroom wall. It looks like someone has salvaged one of those imersion heater switches, the ones with the orange light on them, is this correct? On unscrewing the switch some of the plastic sleaving on the earth wire has come away, exposing bare wire. Further more, the live wire feed from the consumer unit, looks like its been subjected to heat and has melted the plastic sleeving just below where it is screwed into the switch. Can I test the switch, or test whether there is an earth fault using my multimteter. If so how? The shower unit is fairly new and I think it unlikely that it is broken, although I understand that this is perfectly possible. Or should I just call in a professional? Your comments are greatly received.

 

[andy]

The electric shower in the bathroom trips the switch on the fuse box whenever I turn on the power supply to run it

what switch? a MCB or RCD?

 

[shavvy]

You say it`s a new shower. Was this a replacement? Is it more powerful than the old one? It`s possible it`s drawing too much current for the cable suppling it which would cause the melted wiring What is the power of the shower and what size is the cable?
Or possibly the connections in the switch may be loose which would also cause the problems you mentioned.

 

[Andy_E]

Appologies for not giving full details on my problem regarding the shower. It tripped the MCB switch. I removed the shower switch yesterday and inspected the wiring. Wires had melted through the plastic coating, resulting in the live and neutrel wires touching each other. The 'spaghettie' type wiring that had been crammed into the housing box for the switch can't have helped I suppose. I've trimmed back the wires and replaced the switch with a 45amp, double pole, shower switch . Both the supply and load wiring is the thick heavily rated stuff that has been used throughout the house, so I'm happy that its the right wire. And all appears to be working fine again. However, on the basis of Shavvy's comments I think I shall get a qualified electrician to check that all is well. Having just moved into the house I'm aware that there might be a few things that need checking out by someone competant and qualified. Thanks for your comments.

 

[ban-all-sheds]

Both the supply and load wiring is the thick heavily rated stuff that has been used throughout the house, so I'm happy that its the right wire.

I'm not.

You didn't say what rating the MCB is, but that cable for the shower should probably be 10mm², and that will not have been used "throughout the house". The only cables that are used "throughout the house" are 2.5mm² for ring mains, 1.0mm²/1.5mm² for lighting, and possibly (but not very often) 4mm² for socket radials. None of those are suitable for showers....

 

[Andy_E]

In that case I shall be getting a qualified electrician in to check things fully. Thanks for the comments.