'Soft' switch and green corrosion on the other

[auds]

Hi!

I'd just like a quick bit of advice, we have two fused switches in our airing cupboard for the hot water cylinder, one main switch which comes on during the off-peak of our economy 7. The other which is for the immersion. We've stopped getting any hot water from the main off-peak part of the cylinder and the heating engineer thinks it has something to do with the economy 7. Before it stopped working we noticed the switch getting quite hot and then went very soft, the only way I can describe it is that it doesn't 'click' when switching on or off .

I decided to take a look at the switch to see if there was anything noticeable and compare to the other immersion switch alongside, nothing seemed out of the ordinary apart from the immersion switch has this green corrosion like powder across one of the wires and it almost looks like it's been burnt (Pic attached: IMG_0334.JPG). This switch is working fine and the immersion works perfectly but like the main switch gets a little hot. Is this something that we should be concerned about and get an electrician to look at? Likewise is this something that could have happened to the main switch and it burnt out?

Both fuses have been checked and are working fine, both are 13A.

Thanks in advance!

 

[Darkwood]

Sounds like it may have got water into the switch the copper has oxidised green and created a high impedance fault... it may have fused but either way requires replacing, also the source of any suspect leak will need to be found and rectified first.

Best call a professional in to replace the fuse spur, the circuit design sounds strange a 20amp DP switch would be more suited to such a load on for long durations with fusing upstream so again get the opinion of a professional as I'm not there and I may be missing something you haven't told us.

 

[Marvo]

Looks like considerable heat damage to the wiring. Will require replacement of the switch and both cables will need making off again from scratch which isn't a job for a DIY'er. On-peak and off-peak supplies can also be very dangerous to work on, it may seem like they're isolated and aren't live but they can automatically become live when you least expect it.