DIY Doctor UK DIY Forums

Hello.

Discovered this morning the wall switch to the shower wasn't working. After isolating the supply I opened the switch up and discovered that the live terminals looked like they caught fire! the switch the brown and cracked on the live side, the copper wires are black and there is a mark on the wall, so I'm sure steam has got into it. There was a smell aswell when the shower was operating around where the switch was (inside an airing cupboard in the bathroom - surely the electrician who re-wired the place would have fitted a ceiling switch). The wiring in shower unit itself looks fine.

Because of this I would like to move the switch onto the wall outside the bathroom, as it would be easier to move the incoming wire in the cupboard, covering it with the plastic protection trench, and drill through. This would mean adding a new wire from switch to shower (which needs to be done anyway as I'm reluctant to use the same burnt out wire). This I presume would need Building Regulations Part P approval, though myself (and especially my dad if he agrees to help!) are confident in electrical installation.

Would I still need an electrician to carry out (or at least check over) the work, and what type cabling and switch would I need? The shower is an 8.5Kw Neptune Solo.

Also in this cupboard is a wall-mounted switch for an old heating system, which is now home to the rear security light. Do you think I should move this switch aswell?

Many thanks in advance for your help.

HI Andy, the regs say the sw. maybe in a locked enclosure but that is unlikely to be an airing cupboard!!!
I doubt the problem is steam, It is almost certainly due to loose connections.
you are right about needing to get a sparks involved as the cost of registering the job your self would be more than his bill!
He will need to use 6mm cable between sw. & shower and a wall switch is better than a pull sw. due to the very limited room in the sw. box of pull sw.
regards SPARX

Hi Sparx.

I've just opened the switch up completely (as I'm never going to use it again) and inside the plastic by the live terminals has melted slightly and done black, the live terminal switch spring is stuck in off, with the surround plastic cracked and black. It looks like the live feed overheated! The switch is rated for 45A. Is this too low for a 8.5Kw shower?

EDIT: I have just been told by a qualified electrician on another (non-DIY) forum that the switch may have overheated to to bad/loose contacts causing arching. And also that the switch is a cooker switch and should never have been installed in a bathroom!!! Would changing this switch mean I would still need to adhere to Part P or could I just change it by myself?

Hi Andy, if just changing like for like & only replacing part of circuit due to damage then it would appear to be OK to DIY, your shower takes
approx 35.7A so 45A sw. plenty. As we both have said it will be loose connections causing prob. because when first fitted no matter how tight the screws are done up, when on load the cable will warm up slightly, this then presses the copper wire against the brass screws in terms. which 'dents' the copper, when not in use the conductors contract away from screws. This repeated cycle leads to a minute gap which when load applied arcs across the gap causing more heat therefore more expansion,
until oops!.
The answer being to check and retighten after a few weeks usage all connections in circuit! Bit of a pain but cheaper than your 'current' result,
regards SPARX

Many thanks for your advice.

I don't know about lossening, but when I took the old switch off the terminal screw for one of the live wires fell out!!!