Ideas on how to trace a live earth wire?

[PrinceofDarkness]

A simple 99-pence neon screwdriver in the hands of a DIY'er is indeed a most useful tool - simply because it sometimes causes him or her to seek advice.

Any unconnected core of a multi-core cable is bound to receive an induced charge due to its proxiimity to a live core - it's a matter of simple physics.

This induced charge, isn't 'live' as such but it's quite capable of 'giving a belt'. Therefore, unused cores should be safely insulated, and disconnected or unconnected earth cores should be reinstated.



Lucia.

 

[vice]

You more than likely haven't got a neutral at the switch? If there is only one cable at the switch then how do you think the switch would work if there was a live and neutral there?

Hi. There are 3 cables at the switch, live, neutral and an unconnected earth that looks live and isn't connected at the other end. Seems this is getting excited by the live wire. If it was actually connected you'd expect the voltage across the switch for Neutral-Live and Earth-Live. But not in this world.

 

[ban-all-sheds]

Hi. There are 3 cables at the switch, live, neutral and an unconnected earth that looks live and isn't connected at the other end.

No - you do not have a live and a neutral there.

What do you think a switch does?

What happens, in general terms, if you connect live & neutral together?

 

[vice]

Sorry, yes. Not a neutral. In order to deduce whether the earth is truly live, and connected to the live, then unless it is connected to another live wire it does not give the same reading as the actual live to the return (previously referred to as my neutral). So if I'm not getting the same reading across the switch for both live to return and earth to return then live and earth are not connected - maybe? (Switch open)

 

[Taylortwocities]

By 'return' do you mean the switched live?

You cannot use that as any sort of a reference. That conductor will go to the lamp and the other side of the lamp will be connected to neutral (see the pictures).

So, that switch live conductor will have a resistance path to neutral - assunimg it is a GLS tungsten filament lamp. If it a CFL, or a discharge lamp or a SELV transformer you'll get no reliable test path for anything and you'll just confuse yourself even more.

What you are trying to establish is if the earth conductor is actually connected to earth. To do this you need to carry out a continuity test on the earth conductor.
This is described here http://www.tlc-direct.co.uk/Book/8.4.1.htm