UK 13A Sockets keep latching in "on" position

[Richs312]

Hi All,

I have a random issue where switches on 13A switched sockets keep latching in the "on" position. Once it happens the sockets are kaput, with the switch contacts fused together. After removing the socket there is no change.

This has happened so far on two different circuits. First time was on a 2.5mm ring, approx. 30m total length - I replaced the socket, and it happened again 2 weeks later. After replacing it for a second time, so far it has been OK.

Yesterday it happened on a separate circuit - probably around a 50/60m ring. This one is a spur at the furthest point on the ring, spurred in 2.5 to an outside socket. The load prior to noticing the switch was latched on was around 2kw (inductive).

For info the sockets in each instance were Click Deco (x2) and BG - not the best I know, but it can't just be a coincidence.

Any thoughts on this one would be greatly appreciated!

 

[DPG]

Sounds like either a very heavy load being switched on and off, a bad batch of switches, or a particularly slow switching operation. Or a combination of these things.

 

[Avo Mk8]

What is the load that seems to be causing this, that you mention is around 2kW inductive?

 

[HappyHippyDad]

I had this at a customers house.
The socket had an extension lead in it which then had another extension lead, both had large amounts of varying electronic devices plugged into them.
I didn't realise this at first and just changed the socket. The new socket instantly became lodged in the on position as well.
Changed the socket again, and this time split the load, all was well.

 

[timhoward]

I’ve had this in a recording studio where the truss lighting came back to 2 double sockets and all 4 switches didn’t isolate the sockets.
Start up/ in-rush current can be another factor.
Further thinking about the loading and using better sockets are probably the next steps.

 

[Lucien Nunes]

Switch welding is pretty common and usually occurs where the switch contacts are not robust enough to handle the inrush. The circuit itself will have minimal effect on the situation although a long thin (high resistance) circuit might limit the inrush somewhat. The cure is invariably to use a better quality switch.

There are many different metal alloys used for switch contacts for different purposes. The best alloys for low-resistance when on, are not necessarily the best for withstanding inrush. Sometimes manufacturers choose the wrong ones!