Ideas on how to trace a live earth wire?

[vice]

Hi. I just started to change over a light switch and found that the earth is not connected up and is live. The new switches have metal surrounds so I really need to get that earth sorted. The switch on the ground floor outside of the downstairs toilet. So somehow I need to trace this live earth, presumably up (hopefully not down since we've just put a wooden floor down!) and somehow across to the other side of the wall where it will work the lights. What the simplest way to do this? Other earths are not live so must be an issue with this single wire, I think. Thank for all help!

 

[Taylortwocities]

What makes you think that it is live?

Are you using one of those neon screwdriver things, or a proper voltage tester?

 

[vice]

What makes you think that it is live?

Are you using one of those neon screwdriver things, or a proper voltage tester?

Just a neon screwdriver on the metal. Just managed to get into the ceiling rose via the hole for the light and found the other end not connected but also live. Seems like somewhere in between the ends someone has probably put a nail or screw through the cable and joined the live and earth. Thankfully neither end of the earth is connected but it does mean a bit of fun to replace the wire . So my new plan is to put in a new wire up to the ceiling and then try an use the old cable to pull through the new one towards the rose. Perfect for a saturday afternoon.

 

[ELZ4742]

could be a false positve, those neon drivers are useless. better to be safe than sorry though

 

[ricicle]

could be a false positve

 

[ELZ4742]

yup, a false positive. Those drivers can pick up a capacative load from something else which makes you think its live.

 

[plugwash]

A floating wire in a mains cable is likely to become somewhat "live" as measured by a high impedance tester like a neon screwdriver or a digital multimer.

 

[Taylortwocities]

Its time for

Untitled

• Taylortwocities
• 11 Feb 2009
• 20

again.

If we don't hear again from vice then we will know it really is live

 

[plugwash]

IMO neon screwdrivers have thier place, mostly as an extra line of defense. You can think you have a circuit safely isolated but borrowed neutrals and worse can mean it doesn't stay that way as you work. Plus most alternatives need a reference to test relative to which can be a problem if you have missing earths in your installation.

 

[ELZ4742]

personally i think those things should be banned. a wet one of those is the same as using your finger as a screwdriver.

 

[AndyPRK]

use a meter to measure the voltage between the earth and neutral.

 

[ban-all-sheds]

a wet one of those is the same as using your finger as a screwdriver.

Don't p*** on it when you're using it then.

 

[ELZ4742]

a wet one of those is the same as using your finger as a screwdriver.

Don't p*** on it when you're using it then.

when ya gotta go, ya gotta go!

 

[vice]

Well, a false positive it seems to be. Got a multi-tester onto the switch.
Neutral to live - switch closed - 220v
Neutral to the live earth - nothing.

This really means my live is not live. Or is this introducing new neon screwdriver - BANG! and the User's gone.

Am I losing my mind? So because the earth is not connected at all the live is creating enough current in it for the screwdriver to pick up?

 

[1john]

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?