Light switch making a "fizzing" sound

MothballsWallet

TELLIT01 said:

It could be the switch, it could be damp getting into the light in the lobby.  Personally, I don't mess with electricals and would get an electrician in.

I'm not sure it's damp because the switch isn't in the wall close to the front door, it's by the living room door as you walk in.

We bought a new switch anyway, just in case - I chose MK because I know the name and it was about £3.50 in B&Q for the same style as the old switch (they had other makes and designs that were more expensive).

@Jeepers_Creepers and @TELLIT01 Yes, I do know to turn the power off

I turned the RCDs off for the upstairs and downstairs circuits before opening up the switch.

TBH, I'm leaning towards getting an electrician in to check things over properly and fit the switch anyway since the wiring is the pre-2004 colour scheme.

In fact, there's a mains wall socket in the living room that could also be doing with replacement and I'm sure a good electrician would be willing to do both for me in the same visit so it's all safe, and I can watch him work so I can learn what to do for myself.

Jeepers_Creepers

EDIT: Just read your "TBH, I'm leaning towards getting an electrician in to check things over properly and fit the switch anyway since the wiring is the pre-2004 colour scheme.

In fact, there's a mains wall socket in the living room that could also be doing with replacement and I'm sure a good electrician would be willing to do both for me in the same visit so it's all safe, and I can watch him work so I can learn what to do for myself."

Yes, you are clearly happier doing this, so that's the way to go. Anyone should only attempt the below if they know they are both happy and competent to do so.

Please report back with what the sparky IDs.:-)

Original:

If the noise is coming from the switch, and if the lights otherwise light up as normal, and if the MCB or RCD doesn't trip, then it's almost certainly one of the two things outlined before: a switch terminal is a bit loose so the wiring is slightly arcing there, or else it's the contacts inside the switch - the unit is kaput.

So, POWER OFF, undo the switch-plate, pull it out gently, get your insulated terminal driver and check each screw in turn. If you find an obviously loose one, then note it and go on to check the others - give them all a teeny tiny 1/64th of a turn tighter. Only one loose screw? Cool - go back to it and this time undo it and remove the wire to check it. Any signs of scorching? Is the plastic sleeving melted? If there are some signs of arcing but the wire is otherwise ok, then refit it and tighten that screw nicely - hopefully jobbie jobbed. Refit and test.

If the plastic sleeving is melted to the point of exposing more wire than you'd like, then  - if the wire is long enough - trim it until you get to a clean section and refit. If the wire is so short that you cannot do this, strip off a piece of sleeving from a spare wire (hopefully you have offcuts in the garage...), trim off enough of the melted sleeve and slip on the new - tape it securely in place.

If you are careful, you could even see if you can locate the source of the sizzle by observing the back of the undone switch-plate before even attempting a cure - turn the main power back on with the switch in the 'on' position and see if it's obvious where the sizzzz is coming from.

robatwork

Yep if the noise happens a few seconds AFTER turning on, that doesn't sound so much like a loose connection, more like a faulty switch.