live earth wire

[mickyw]

i recently changed a plastic lightswitch for a chrome one, on tightening the wires my neon lit up when i connected the earth. when i noticed this i checked the other switches in various rooms and noticed at least 3 more were live, any idea,s anyone ? as getting a sparky to come out for small jobs seems almost impossible

 

[davelx]

Sounds like the earth conductor in your lighting circuit is not connected back to the earth terminal in the consumer unit (CU) and is picking up a voltage due to coupling (it does not take much current to light a neon screwdriver).

This could simply be because the earth connection in the CU is loose/broken, or it could be a break somewhere between the CU and the affected switches, or it could be that the lighting circuit doesn't really have an earth at all!

Can you check all the switches on the circuit, and ideally with a multimeter rather than a neon to get an actual voltage reading. How old is the lighting wiring and what type of CU do you have?.

 

[JohnD]

my neon lit up when i connected the earth

throw away the neon tester and buy yourself a multimter for about £8 in the high street.

Neon testers are notoriously unreliable and misleading.

 

[mickyw]

thanx davelx and johnd for fast relpy, my cu is an old fuse wire type with a seperate mb? type for shower, wiring looks quite modern although untidy, house is 100 yr old, neon is dull when light is off, goes brighter when lit, would this problem cause flickering lights, as this seems to be happening more regular too
thanx again guys

 

[bernardgreen]

my neon lit up when i connected the earth

throw away the neon tester and buy yourself a multimter for about £8 in the high street.

Neon testers are notoriously unreliable and misleading.

Incredible but I have seen a neon light up when touched on metal water pipe coming up from the ground into a kitchen. Touching the pipe with the other hand the neon when out.

They are not reliable and can give dangerously wrong indications

 

[RF Lighting]

on tightening the wires my neon lit up when i connected the earth.

Were you working with the circuit still live?

Favorite cause for this is a floating earth (Not connected somewhere) as suggested earlier on