Light switch making a "fizzing" sound

MothballsWallet

Hi everyone,

I've got a question around something that's happening with one of our light switches that started in the last few weeks.

We've got a light switch in our downstairs lobby that allows us to control the lights in the downstairs lobby and upstairs landing from the same double switch - there's a second switch upstairs that's for the upstairs landing light alone.

From what I've learned from reading up about the electrics, the downstairs switch is a "2-gang, 2-way" switch, and is configured with the left hand switch for the downstairs light and the right hand switch for the upstairs light, and the upstairs switch is a "1-gang, 2-way" switch.

When we switch on the downstairs lobby light, we can hear what sounds like a "fizzing" noise, but it doesn't happen every time we turn the light on, and Mrs MbW and I think it's a fault in the switch itself.

The switch is the original one from when the house was built as we've never had a problem with it until now, so we bought a replacement MK/Honeywell brand 2-gang 2-way switch from our local B&Q and I just need to fit it, but wanted to see if there are any other possible causes in case I need to get an electrician in because I don't want to mess around with mains electrical wiring and the consumer unit if I don't have to.

Many thanks in advance.

FreeBear

Possibly a loose connection. Be as well to go round all the other light switches & sockets and check that the screws holding the wires in place are tight.

If you are not confident around electrics, get an electrician to do the checks.

TELLIT01

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.

Elmer_BeFuddled

^^^^^^^^^^^
Wot he said!

Hasbeen

Op if you are any way competent, fit the new switch. But would suspect loose connection or moisture.

twopenny

I had this with a switch. Just switching off the electric and taking the cover off to check should be reasonable.

I even changed the switch and it made no difference. Then one day it all went back to normal.

Alanp

Light switches can make a noise as you turn it on, but it could be faulty
does it make the noise as you switch it on, or does it make the noise after it’s turned on ?

fenwick458

it's a common thing, switches fail. if your switch is making a fizzing or cracking sound then it's either the switch contacts are faulty (this means replace the switch) or one of the terminal screws are loose
1st thing to check is the connections, often it can just be a lose terminal screw
if not then go ahead and fit the switch. just take a picture of the switch terminals and wiring before you start. do it in the daytime, turn off the lighting circuit at the MCB before you take the switch off

Jeepers_Creepers

As Fen says - if you do decide to replace the switch (ie you've checked the tightness of the terminals and it ain't that), then take a crisp clear photo of the existing connections, along with a sideways show to show the cables coming in to the backbox and going to the switch.

Make certain you can ID every single wire and where they go, because some will be the same colour! If necessary, add taped labels.

Finally, compare the new switch with the old - the terminals might well be labelled differently. Don't be thrown by this - almost certainly you can relate the two. But get it COMPLETELY clear in your head BEFORE you start; "The red in 'com' goes to 'L' in the new switch etc etc etc."

Oh, you will turn the power off...? :-) 

TELLIT01

Jeepers_Creepers said:

As Fen says - if you do decide to replace the switch (ie you've checked the tightness of the terminals and it ain't that), then take a crisp clear photo of the existing connections, along with a sideways show to show the cables coming in to the backbox and going to the switch.

Make certain you can ID every single wire and where they go, because some will be the same colour! If necessary, add taped labels.

Finally, compare the new switch with the old - the terminals might well be labelled differently. Don't be thrown by this - almost certainly you can relate the two. But get it COMPLETELY clear in your head BEFORE you start; "The red in 'com' goes to 'L' in the new switch etc etc etc."

Oh, you will turn the power off...? :-) 

I was amazed that so many people had given advice before anybody added that bit. :-)

The comment about comparing the switches is very important too.  I've had a light switch with built in timer for years and the timer/sensor stopped working.  Ordered what appeared to be an identical unit but the wiring is completely different.  Rather than mess about with it I'm currently managing to get by without the timer part.

MothballsWallet

Alanp said:

Light switches can make a noise as you turn it on, but it could be faulty
does it make the noise as you switch it on, or does it make the noise after it’s turned on ?

The noise starts once the switch is turned on - sometimes it takes a second or two before it starts - I did shoot a video clip on my phone, but the audio's not as clear as I'd like it to be, I might be able to boost the level in my video editor before I can post it, if that would help.

Edit: Thank you for the advice so far.