Electric shocks from metal light switches

[MattB83]

Maybe a daft question but...

I get small shocks when I use my downstairs chrome light switches. The same sort that you get from a car door on a hot day. Sometimes if an appliance like the washing machine or dishwasher is on its almost like the switches vibrate.

Would changing to plastic switches solve the problem or is this something potentially serious?

(Today I had slightly clammy hands and the shock has actually given me a blister).

 

[JohnD]

You have an electrical fault. Static won't do that. Turn off the power, take one of the switch plates off, photograph the wires and connections inside. I am especially interested in any bare wire, or green or green-and-yellow sheathed.

Don't forget to turn off the power

Was your house by any chance wired or rewired in the 1960's or 1970's?

 

[JohnD]

p.s.

to rule out static, with the power on, stand in front of the switch on both feet. Tap the switch with your knuckle. Do you get a shock?

Without moving your feet or other limbs, tap it again. Is it the same or different?

You may need to wear the same shoes (or have the same bare sweaty feet) as last time, and the same clothes, as synthetics are different to natural fibres.

 

[MattB83]

You have an electrical fault. Static won't do that. Turn off the power, take one of the switch plates off, photograph the wires and connections inside. I am especially interested in any bare wire, or green or green-and-yellow sheated.

Was your house by any chance wired or rewired in the 1960's or 1970's?

Thanks for your response. The house was built in the 50's and I'm not sure what's been done since then. I'll take a photo asap. So it could be a localised problem (i.e. the wiring of the switch) rather than a fundamental house wiring issue?

I also suspect the previous owner of doing lots of things himself. Someone had screwed a light fitting through a wire upstairs and this took a while to get to the bottom of.

 

[JohnD]

So it could be a localised problem (i.e. the wiring of the switch) rather than a fundamental house wiring issue?

I think more likely the second. We'll see.

 

[MattB83]

p.s.

to rule out static, with the power on, stand in front of the switch on both feet. Tap the switch with your knuckle. Do you get a shock?


Interesting - nearly always when I'm barefoot and in my synthetic dressing gown. Wife has only had a shock once, I get one most days. It's usually my knuckle rather than finger.
Without moving your feet or other limbs, tap it again. Is it the same or different?

You may need to wear the same shoes (or have the same bare sweaty feet) as last time, and the same clothes, as synthetics are different to natural fibres.

 

[JohnD]

any update?

 

[MattB83]

any update?

Hey sorry for delay. I chickened out of doing it myself. My thinking was that if there's something wrong and it needs more than a chance of switch I may not know. I've got an electrician coming around today.

Thanks for your help.

 

[MattB83]

any update?

So a sparky came around today, it seems things in the house are quite messed up. I'm just quoting him but the voltages are apparently different at different switches and earth wires are carrying voltages too. So he's changed switches but thinks it's still going to give me a shock.

I've been up on the loft taking off all the boards so he can check all the wiring. Also he changed the shower pull switch and the wires had all melted together.

He's coming back later in the week to try to get to the bottom of the issue.

So my next shock will be the bill!

 

[JohnW2]

So a sparky came around today, it seems things in the house are quite messed up. I'm just quoting him but the voltages are apparently different at different switches and earth wires are carrying voltages too. So he's changed switches but thinks it's still going to give me a shock.

Hmmm. That's all a bit vague, and I really don't see how changing switches would alter anything. Is this an electrician that you 'know and trust'?

Kind Regards, John

 

[Harry Bloomfield]

Hmmm. That's all a bit vague, and I really don't see how changing switches would alter anything. Is this an electrician that you 'know and trust'?

..and a properly qualified guy?

 

[RF Lighting]

Sounds like a floating CPC “earth wires carrying voltage”

It really seems to confuse a lot of “electricians” when armed with a high impedence volt meter and they start testing between an open CPC and line or true earth and they get a reading of 100V or so.

I’m assuming that he’s changed the metal switches for plastic which is a bit better, but realistically the circuit needs disconnecting from the power until it is made safe for use. I certainly wouldn’t be happy leaving an unsafe circuit energised after I’d worked on it and telling a client they might get a shock!!

 

[MattB83]

Thanks all,

Yes properly qualified - I don't know anyone around here but he seems like a good bloke and he was insistent that he came back to sort the problem properly and he's been around every light and switch in the house to identify the fault. So after we unboarded the loft we're now lifting floorboards upstairs as looks like we need a new cable between two of the lights.

 

[aptsys]

Sounds way too vague for someone who knows what they're doing. Changing to plastic switches is not an acceptable fix, especially if it has the potential to cause issues on any Class I device.

Get someone out who knows what they're doing - already sounds like a main earth fault if the washing machine makes a difference.

 

[RF Lighting]

Randomly prodding around lights and switches and now pulling up flooring on two levels of the house doesn’t sound like the right way to solve what really isn’t a particularly complicated fault.

I’ll bet you £1 that it is not a failed bit of cable.