On Mon, 3 May 2021 13:14:18 +0100, Robin wrote:

On 03/05/2021 09:38, Jedzi wrote:

I've got an ancient, maybe 40 or 50 years old, switch for the immersion heater in my airing cupboard. It's a thin-ish one, mounted on the wooden door frame.

Increasingly, it gets hot in use and has started to smell slightly (I think it's a heated plastic type smell).

Is this "increasingly" without other changes (eg in the time the heater
is on or the temperature in the house)? If so it may be that you have a
bad connection in the switch where temporarily at least tightening the
screws might help. See under "High resistance connections" under "Types
of Fault" in

http://wiki.diyfaq.org.uk/index.php/...Faults#Effects

And under "Inspection procedure" see the entry in the table for "High
resistance L/N".

But do please note the rubric to the table: "Power must be switched off
before any inspection takes place." And - with apologies if I'm
instructing in the sucking of eggs - in this case that's most
emphatically off at the consumer unit, not at the switch

My screwdriver is rated at 1,000 Volts. I think the instruction
actually states 'Any appliance should be switched off and unplugged
before working on it.' It seems to me this does not preclude an
inspection provided suitable precautions are followed.