A weird thing with an electrical screwdriver

They are not bad. I trust them on T&E cables if used properly.

Adam

Reply to
ARWadsworth
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On Fri, 11 May 2007 16:44:31 GMT, "ARWadsworth" mused:

Yeah, although I've only ever used the MK and Fluke ones. I've seen people with unbranded\cheap ones and they are somewhat erratic.

Just remember not to use it as a sole means of testing when your having an NICEIC inspection. ;)

Reply to
Lurch

Sorry John, that's completely wrong. There's no way you'd get enough inductive (electro_magnetic_) coupling in this sort of situation to induce a voltage high enough to light a neon.

Capacitive coupling is the mechanism involved here, aka electro_static_ induction (note induction, not inductive). What was probably happening was that the OP's body was near enough to a live cable to pick up a significant voltage (there's no shock felt of course because any current flowing is tiny (microamps) and there's no point of skin contact). The sharp end of the screwdriver was in contact with an earth or neutral terminal and it was the user that provided the 'live' connection to the blunt end. You can get similar 'false positive' effects when using a 'volt-stick' type of indicator with your body near to a live cable.

Moral: always use a proper voltage indicator or test lamp and test it on a known live supply (or proving unit) both before and after isolating & checking the circuit you intend to work on.

Reply to
Andy Wade

Yup, you could well be right thinking about it... different case from false positives with a high impedance DVM.

What sort of strike voltage does a neon need?

That would better explain the thing lighting on the neutral and earth wires since unlike the live they would not have been left floating by pulling the fuse.

Can't argue with that!

Reply to
John Rumm

I only do minor electrical stuff like changing lights. My proceedure is;

Switch light on, check with volt stick to ensure volt stick is working. Remove fuse/turn off breaker for relevant circuit. Check again with volt stick.

I assume thats safe enough?

Reply to
The Medway Handyman

On Sat, 12 May 2007 10:29:36 +0100, "The Medway Handyman" mused:

Bit OTT for me, if there's a lamp in the fitting the volt stick stays in the tool box. ;)

If you know what you're doing with a volt stick they're safe enough, but technically trhey're for an indication of voltage rather than a tester as such.

Reply to
Lurch

No, because if you rewrite your procedure:

Switch light on, check with volt stick to ensure volt stick is working. Remove fuse/turn off breaker for hopefully-relevant circuit. Volt stick breaks. Check again with volt stick. Get shock.

you can see the flaw.

You must check your tester on a known live supply *before* AND *after* checking the circuit to ensure your tester is not broken and giving you a false negative.

Also, when you say "turn off" you should say "lock off" unless the CU is under your control whilst working on the circuit. Electricity At Work Regulations apply to you.

Owain

Reply to
Owain

Usually in the 60 - 90 V sort of range.

Reply to
Andy Wade

I do - thanks.

Easy enough to do.

If its a fuse I put in in my pocket. How would I lock off a breaker?

Reply to
The Medway Handyman

On Sat, 12 May 2007 13:36:26 +0100, "The Medway Handyman" mused:

Not actually an acceptable method, technically.

With a padlock, used on a breaker with lock off facilities or with a MCB lock off kit.

Reply to
Lurch

Far better to kick everyone out of the house and lock the doors. After they've made the tea, obviously.

Reply to
Dave Plowman (News)

On Sat, 12 May 2007 16:48:12 +0100, "Dave Plowman (News)" mused:

Only if you ensure the doors can't be re-opened by unauthorised personnel.

Reply to
Lurch

And you've carried out a risk assessment and followed procedures for lone working.

Woulnd't be too clever to lock everyone else out and then electrocute yourself.

Owain

Reply to
Owain

On Sat, 12 May 2007 19:39:57 +0100, Owain mused:

I think the moral of the story is don't do electrics unless you are an electrician, not a handyman.

Reply to
Lurch

Which would leave large numbers of people who wanted small, simple jobs done waiting for electricians who don't turn up, don't call back and generally can't be arsed with small jobs - and charge an arm & a leg if they do ever arrive.

Apart from which, if the dreaded Part P says it's OK, then it's OK.

Personally I think electricians & plumbers should be banned from attempting to 'make good' after their work, since they are clearly incompetant - on second thoughts they should be encouraged to do so - it provides me with lucrative work.

Reply to
The Medway Handyman

On Sat, 12 May 2007 20:45:34 +0100, "The Medway Handyman" mused:

OK.

Depends, case by case really. Some are genuine mistakes, some are just incompetent.

Reply to
Lurch

The moral of the story is use a proper tester and testing procedure every time.

I can still remember the time I assumed that because the bedroom and kitchen sockets were dead the lounge one would be. How was I to know it had been wired onto the same 15A fuse as the bathroom wall heater, immersion, and garage socket.

Owain

Reply to
Owain

With those I work on the principle that when the lights on my socket tester go out there is a fair chance I have identified the circuit.

Reply to
John Rumm

Indeed. A similar situation prompted me to ask the question. It's amazing what you find in peoples houses...........

Thanks for the advice - proceedure changed.

Reply to
The Medway Handyman

Yes. Never ever assume anything with electricity. What is a logical layout to you almost certainly isn't to others. And that's before pragmatism comes into the equation.

Reply to
Dave Plowman (News)

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