Neon Screwdrivers....

[BestGear]

Hi Guys

I was using a neon screwdriver in friends house, to confirm the power had been removed at a ceiling lighting junction box.

The junction box was to be replaced - a straight swap as something in the attic had fallen on it and cracked the casing.

I brought in the feed live, neutral and earth first, noticed that if I touched earth or neutral with the neon screwdriver, the neon lit up!

Obviously I was not expecting that... so assume the earth impedance is kind of high, and as for the neutral - gob smacked that it was not at earth potential..or very close to...

I made good the repair and left him to get it checked by a pro...

What do you think?

Is this common?

I did not use a meter to measure impedance or even floating voltage on the earth or neutral, which I could have, but when it was enough to light a neon (which is min 90v from memory) I walked away...

I appreciate that the current to light the neon is tiny, but surely that ain't right!?!?!?!

Thanks

David

 

[Darkwood]

All you need to know is as students the colleges ban neon drivers they pick up induction are misleading and if they fail you may think a cable is safe when in fact its live..... the only reason they are not banned in the UK they have an alternative function of turning screws.

 

[telectrix]

and cleaning out the nozzle on your tube of caulk.

 

[ian.settle1]

Should be banned by law there bloody dangerous

 

[Johnuk]

I only use the screwdriver end

 

[Tiny Spark]

I used to have one of the blue plastic ones which used to come in handy for quick indication testing.
But I certainly would not trust them or use them for proving dead.

A quality multi meter is where its at.

 

[BestGear]

I fully understand what you are saying Guys...

BUT - what do you think re it illuminating on E and N?

 

[Tiny Spark]

They will pick up on the most tiny currents.
You may of had a small amount of earth leakage or something.

 

[BestGear]

They will pick up on the most tiny currents.
You may of had a small amount of earth leakage or something.

Should my mate live with it or worry?

I guess the answer is to measure it and see how bad it is!

I will check to see if the lights are on a RCD... there is a split load CU.. and only half is on a RCD... so the lights may not be.

David

 

[Tiny Spark]

To be honest its not something I would worry about.
As I said above, they are not to be trusted and should not have any faith put into them.
If you want to test the circuit or the installation in general you should use the proper gear or get someone to do it for you.

 

[telectrix]

........ using a neon screwdrver to test for dead............ dipstick. rely on one of them you could end up dead.

 

[Guest111]

I once had a neon light up on a 6mm t&e that was cut off at both ends,I know it was dead because I isolated it,they are not safe or reliable,one of the lads had one and he just used it as a screwdriver anyway the apprentice dropped it in the sink dried it off and said nothing.The spark went to check a loose connector on a ceiling rose and the power was still on,bang and he ended up on the floor,Yes it should have been isolated,yes the apprentice should have said he'd dropped it in the sink,but ultimately if it had been an ordinary driver he wouldn't have got the belt.

 

[Wiresandthings]

http://youtu.be/AGXQNLq19FQ

This should give you an insight as to why these drivers are bad, and if you watch to the end you'll see how good a decent insulated driver is at protecting its user

The bloke in the video is a nutter but he does some pretty cool stuff on his other vids

 

[BestGear]

Ok, so I think we have ascertained you lot don't like neon screwdrivers...

So what is the likely cause of the earth and neutral being above (or below!) 0v potential to light it up?

Regardless of what the test tool was, it showed that there was potential between earth (me) and something that should have been at the same level.

Explain it to me in terms of what you have found in the field (ie real life, not hypothetical) causing it... dont treat me like a dipstick... and I am happy for any detailed electronic explanation...


David

 

[Marvo]

First thing to do is to test the circuit using a suitable instrument.