Subtle electric shock from metals - any ideas?

[Chrispla]

I have recently moved into a house and replaced all the light switches with brushed steel face plates. When touching the face plate, you get a small constant electric shock that is definitely not caused by static. It is not painful, but is annoying!

Funnily enough it also happens when you touch the gas hob which is stainless steel (hob draws current and is earthed into the cooker mains - gas but has electric component for ignition of burners)

I have also noticed the same shock when touching the chrome effect on the front of the DVD player. The DVD player is not earthed - has a simple A/C fly lead that pushes into the back plate with two terminals.

Any thoughts would be most welcome.

 

[2scoops0406]

Get an electrician in ?

 

[Chrispla]

Yep - that is the most obvious solution, but could do without spending a London based elcticians call-out charge if it is a comon or simple resolution . . .

 

[Lectrician]

Video chassis is probably earthed through the aerial screen.

You need a sparky, as he will have the necessary test kit to ensure you have a suitably low resistance earth path.

 

[felix]

Question one: How old is the wiring in this house? Assuming it's not in urgent need of a total rewire, the problem is with your earth. From the sounds of things you haven't got one. All those metal plate switches and your gas hob will be connected to earth wires which lead back to the consumer unit. From there you should have an earth connection coming in with the main power cable or, just possibly, attached to a ground spike. Since everything in the house is affected, the problem is almost certainly at this final link from the consumer unit to true earth. It's missing!

Earth wiring that isn't connected to anything picks up voltage by capacitive coupling from adjacent cables. In flat twin and earth, which, hopefully, makes up the bulk of your wiring, a floating earth wire will sit at about 120 volts. This is quite enough to make your hand tingle - and also enough to light a neon screwdriver though it will be a feeble light. Although the DVD player is double insulated, this 120 volts can still get in through video leads from other equipment.

You can't afford to leave it like this. If any single electrical item in the house develops a live to earth short circuit, ALL your earthed metalwork will become live. That neon will then glow brightly and so will you!

The solution may be as simple as finding that an earth wire from the consumer unit has come adrift. Unfortunately, it might be that your house simply doesn't have an earth. Perhaps it vanished some time in the past when somebody replaced an old lead water pipe with plastic - or maybe it never existed in the first place. If you can't see anything obvious then I think you'll end up paying those London rates

 

[mapj1]

Look in 'for reference' at the pictures of TT, TNS and TNC supply arrangements - which if any matches what is by your meter?
Look for where the green/yellow wires join up and then connect to something that goes outside either connected to the cables belonging to the electricity company, or if your feed is only 2 wire, it could go, as suggested to a buried rod or plate. (and may have been accidentally dug up/rusted through cut with the lawnmower... whatever.)
Does the installation have an RCD. Can you take a picture of your meter and company fuse arrangements - if you can post it someone should be able to specify a bit more so you know what work needs doing, evein if you cant do it.. However, it does sound rather like the main earth might have dropped off before reaching terra firma proper.
regards M.