Help with switch (electrics)

[ss]

I noticed a `fishy`smell when shower was being used. I checked the isolator switch outside the bathroom and it was hot so have now switched off at the main electric box. I have opened up the switch and there is obvious signs of heat damage and one of the cables was loose I think it is the neutral. The bakelite plastic stuff inside the switch looks like it has suffered heat damage. I think its fair to say the switch needs replacing but what about the cable as there doesnt appear to be any slack. I am ok for replacing the switch myself but beyond that I would call in an electrician. Would winding insulation tape on the damaged cable be suffice or would the cable need replacing?

Picture at link below.

other comments welcome. thanks

[Bob Minchin]

In your position I would build up the damaged insulation overlapping onto to the undamaged surface with a few layers of heat shrink sleeving making sure that the original colours are still visible. Obviously fit a new switch of the correct rating and tighten the terminals well.

[John Rumm]

I would replace the switch. Strip off any badly damaged insulation, and then sleeve in either silicone insulation, or heatshrink. Use a fine abrasive to clean the termination surfaces of the wire so that you remove any tarnish or heat bluing. Then re-terminate in the new switch. Use a well fitting (and large enough) screwdriver and make sure the connections are tight (fractions of an ohm matter on these!)

[Dave Liquorice]

Oooo 'orrible. Sorry I think you are into replacing the cable. Looks like it's already been bodged once... Is that a butt crimp connector revealed under the tape on the live?

Ideally you replace the entire length of cable that is damaged(*). Is that going to the shower or the CU? You could just replace from the switch to a void and have a joint but with the high current demand of a shower you have to ensure really good, secure, reliable, connections or you get overheating. Bear in mind metal creep and thermal cycling. Having this "hidden" in a roof or floor void is not a Good Idea.

(*) It might require both the feed in and the feed out to be replaced. If the other cable has suffered heat damage as well.

[Owain]

obtained. In any event, the outer sheath of the cable must be brought within the dry lining box, possibly if you replace with a double box you'll get enough slack within the box area.

[Bill Wright]

That can happen when she holds the shower head low down and points it upwards.

Bill

[Bill Wright]

The best way is to make a soldered joint. Professional electricians won't agree but that's because they don't know how to solder.

Bill

[meow2222]

The cable can be reused as long as the copper hasnt melted anywhere, but yo= u'll need to sleeve the affected conductors, and strip off any blackened or= charred insulation first. Insulting tape is legally sufficient, but is alm= ost sure to fall off eventually, so sleeving is a bit better. I'd be sure t= o position the conductors such that even if all insulation drops of they wo= n't touch.

The copper end that goes into the screw terminal must be bright copper, scr= ape thoroughly with a knife, don't skimp on this point, get it immaculately= bright.

NT

[ss]

you'll need to sleeve the affected conductors, and strip off any blackened or charred insulation first. Insulting tape is legally sufficient, but is almost sure to fall off eventually, so sleeving is a bit better. I'd be sure to position the conductors such that even if all insulation drops of they won't touch.

thoroughly with a knife, don't skimp on this point, get it immaculately bright.

Thanks for all the useful advice, much appreciated.

[ss]

Ok I have fitted a new switch and all appears to be working ok. Question though as not being an electrician I will be neurotic over this switch for a couple of weeks. My wife just used the shower but was in/out in no time just in case. The switch is not now heating up and there is no foul smell, however as I will no doubt check this switch everytime the shower is used for a while should the switch heat up at any time given that say some showers maybe 10 minutes duration?

thanks

[Bill Wright]

It might get slightly warm. Only slightly though.

Bill

[ss]

thanks Bill

[John Rumm]

It may get warm...

Remember the maximum current carrying capacity of a cable is dictated by its temperature budget. So if the shower is using an appreciable proportion of that, then the conductors may be running at close to 70 deg C when at full temperature. That in time will heat the switch a bit even if it suffers little resistive heating on its own.