live earth on lighting circuit

[yorkshirelad]

Hi, i was hoping you could help me. We have recently bought a house, i replaced the old light fiiting in kitchen with a new bar of 4 spotlights. Whilst checking the electrics after i noticed that the earth was live (tingle off the light fitting prompted me), i checked the other rooms, the living room (nxt to kitchen) that was live, but the other downstairs room (with fuse box in it) was not. I checked the voltage between light earth and ring main earth in the kitchen and it was 100V. I am planning to get a sparky in to look at it asap, but i was hoping you could give me an idea of any checks i could do in the mean time? I have taped over the screws on front plate to prevent any shocks. The house was built 1900 but has been re-wired at some point but we dont know when. Thanks

 

[Spark123]

Sounds like the circuit protective conductor (earth) is open circuit somewhere.
You could check the light fittings to make sure all the earths are connected together in each, and that no 2 core lighing circuit wire without an earth is present.
Remember to turn of the electricity before removing any covers.

 

[yorkshirelad]

Thanks Spark123 for the prompt reply, i will do that today. I was concerned that i had a faulty light on the circuit that was leeking current to earth, but i was conused by the voltage difference being 100V not 240V. I have seen that there is some redundant 2-core wiring to some wall lights that have been removed and terminated in connector blocks, but most of it seems to have earth present. The wiring in the house needs a good check over, i have checked the mains sockets and several of the earths were not connected to the socket front, i think the lighting circuit needs the same treatment.

 

[Spark123]

Possibly, it might be in your interest to have a periodic instpection report carried out by an electrician to give you an idea of what work needs to be done to the installation to bring it up to scratch.
The 100v is typical of a floating earth conductor, floating meaning it isn't connected to earth. The voltage is usually caused by capacitance of the cable and is measureable using a digital volt meter, the break could be anything from a broken conductor, a loose connection or a piece of cable in use which doesn't have an earth conductor.
Sockets should always have the earths connected to the face plate - I consider it good practice to fit a link between the socket and sunk metal back box, however if at least one lug is fixed this may not be required.