50v on CPC on front plate.

View the thread, titled "50v on CPC on front plate." which is posted in UK Electrical Forum on Electricians Forums.

D

danspark12345

So, I'm stuck.

There is a metal light switch, which has a noticeable vibration to it when you touch. Like a humming on your finger.

It is a 2 way at the bottom of the stairs. The 50V is only present when the lights are switched on. I tried changing the switch, no effect.

I haven't a clue! What it could be.

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Your earth/cpc is not connected to earth correctly.
The test you did should show 230 volts.
Test from switch earth to a proper earth ie a socket screw
 
There are a couple of things that could be wrong.
It may be that you are measuring an induced voltage on an otherwise dead leg of the strappers .
It could be a faulty switch with a large voltage drop across the contacts.
 
The earth wire is connected at the switch OK, but that does not mean that the earth wire is connected all the way back to the fusebox. It probably goes through several joints on the way, and it's likely that one of these has come adrift.
 
James said:
It may be that you are measuring an induced voltage on an otherwise dead leg of the strappers .
Click to expand...
James makes an important point here. Did you measure the voltage on the blue wire as well as the yellow? If the blue is the strapper in use, and measures 230V, then a random induced voltage on the yellow, when measured with a high impedance meter, would be normal and expected.
 
brianmoooore said:
James makes an important point here. Did you measure the voltage on the blue wire as well as the yellow? If the blue is the strapper in use, and measures 230V, then a random induced voltage on the yellow, when measured with a high impedance meter, would be normal and expected.
Click to expand...
I will do this 🫡

But, any idea why my volt meter, flashes showing AC volts (no measurement) when I put it on the metal face plate?
 
It may be that there is a dangerous voltage on the switch faceplate.

Ideally you would start with an earth loop impedance test to the faceplate.
this would confirm if the faceplate is reliably connected to earth.

I think because of the possibility of a dangerous fault hiding in there, you would be well advised to seek some professional help.
 
The last time I had something weird like this with a non contact tester lighting on earthed metal, it turned out that the earth was okay and it was me that was live as a result of a spiked live wire in a nearby concrete wall.
 
James said:
It may be that there is a dangerous voltage on the switch faceplate.

Ideally you would start with an earth loop impedance test to the faceplate.
this would confirm if the faceplate is reliably connected to earth.

I think because of the possibility of a dangerous fault hiding in there, you would be well advised to seek some professional help.
Click to expand...
I'll try this, thank you!

Currently on my NVQ so trying to learn!
 
danspark12345 said:
I'll try this, thank you!

Currently on my NVQ so trying to learn!
Click to expand...
Hello Dan ,

All of the above checks need to be done first, Many meters are sensitive to any stray Voltages , stray voltages are Normal and can be detected, A GOOD solid earth on the plate should remove most of it down to a Few Volts
 
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