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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 31st Jul 2019, 10:50 pm   #1
Julesomega
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Default Neon Tester Screwdrivers

We all have to work on mains wiring at times. Even if you can afford to pay a qualified electrician to maintain your fittings there will come a time when you cannot wait til next week to have the heating, cooling, or the shower fixed.
That's when you get out the old trusty neon tester screwdriver and rely on it to confirm that you've disconnected the right circuit.
I was called to fix someone's electric shower this week and got out the two neon testers I carry in the toolbox. The sun was shining onto the white bathroom walls which makes neon testing difficult at the best of times and the cheapo small tester did not light up, however the better and larger tester could just be perceived to be lit when touched, which protected me from a bit of consternation.

On the way home I called into a DIY store and bought their good quality tester, branded Wera. This is nicely made, with a proper 150k resistor visible. I love the pocket clip for its elegant simplicity. A reviewer posts as follows: "As an Electrician I would never depend on this type of tester to prove the power is off. I use this screw driver as a terminal screwdriver as it clips into my overall top pocket. To test the power is off a test meter is a must even using a test meter you are advised to test the meter before use and after use to confirm the meter is still working. Electricity can Kill!!"

Dismantling the failed cheapo unit by snapping it open reveals some kind of resistor substitute like a tube of dark crystals which measures o/c ie >10Mohm. The same happened with an identical one I had earlier. DO NOT buy these and throw away any you find.

Speaking of old faithfuls, I still use the Vitrex tester I bought in 1970. The pocket clip has long since broken off and the top is broken off: that used to carry a spare plug fuse and allowed you to test other fuses, blown/not_blown. The blade is indestructible.
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Old 1st Aug 2019, 10:19 am   #2
Mike. Watterson
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Default Re: Neon Tester Screwdrivers

Neon test screwdrivers were a banned thing in the BBC when I worked there. I used them till I was about 17 and realised they are potentially lethal:
* Dirty water can get in as most are not sealed (shock risk)
* The neon can short or crack (false negative)
* The resistor can go open circuit or crack (false negative)
* The resistor can short out (shock risk)
* The metal screwdriver part often isn't well anchored thus resulting in a damaged neon
* It's possible for it NOT to light on a live circuit depending on footwear / flooring

Use a DMM or other certified tester.
The only use is as a source of a neon for a project.
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Old 1st Aug 2019, 12:01 pm   #3
pmmunro
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Default Re: Neon Tester Screwdrivers

This is what electricians are taught these days.

https://www.electricalsafetyfirst.or...actice-guides/

The essential equipment is a suitable voltage indicator and either a know supply or a proving unit. The voltage indicator has to be proved to be working before and after checking circuits are not live. Note that multimeters are not encouraged due to risks associated to their being set to an unsuitable range. Three test to be made on single phase supplies, ten on three phase supplies.

Possesion of a working voltage indicator and proving unit, or a tester with built-in proving is essential to passing the annual assessment by any of the Scheme Providers, NICEIC, SELECT, NAPIT, etc. with whom electricians should be registered.

"Voltsticks" are another questionable type of indicating device. It can be argued they are useful for proving circuits are live, but certainly not that they are dead.

PMM
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Old 1st Aug 2019, 1:15 pm   #4
Ian - G4JQT
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Default Re: Neon Tester Screwdrivers

I have a screwdriver with a small battery and an LED rather than a neon. It is also useless as it lights up whatever metallic object you touch!

These screwdrivers are only useful because their blades fit most electrical screw connections, although I don't think most are particularly rugged - not like the old yellow GPO screwdriver sets. They last for ever and ever!
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Old 1st Aug 2019, 1:35 pm   #5
Mike. Watterson
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Default Re: Neon Tester Screwdrivers

I agree a DMM is risky, but much safer than a neon screwdriver. It's only if you have nothing more suitable as a DIY person.
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Old 1st Aug 2019, 1:41 pm   #6
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Default Re: Neon Tester Screwdrivers

I must have tested a thousand or more for live chassis using the old style neon test screwdriver when I was in the trade, never had a miss, maybe I was lucky.

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Old 1st Aug 2019, 2:03 pm   #7
Sideband
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Default Re: Neon Tester Screwdrivers

I still have one I bought in the 1970's. They were a must for testing live chassis. Never had a miss with it. Still works although I can't remember when I last used it purely as a mains tester. I now call it my 'plug' screwdriver.
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Old 1st Aug 2019, 7:31 pm   #8
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Default Re: Neon Tester Screwdrivers

Growing up in the 70's as a curious onlooker whenever an electrician came into our house, I can say that they all used neon screwdrivers. One of the electricians had an Avo 8 but he only brought it out of the van to show my mother the sort of thing she should be buying me for christmas (it never happened!).
As a trainee, my boss also used a neon screwdriver, no voltsticks in those days.
I used one as a double check I'd pulled the right fuse when I first started the day job, and was later given a 'trolex' volt stick by a recently retired electrician; a highly prized, expensive and novel piece of kit.

Since the advent of digital meters I've never used one, though I keep a volt stick in the toolcase for site work as a double check that circuits are dead.

Last month was my birthday and I was given the latest top of the range 'Facon' VDE approved screwdriver set, including a neon screwdriver. It's marked 'CAT II 100-250V AC'.
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Old 1st Aug 2019, 7:38 pm   #9
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Default Re: Neon Tester Screwdrivers

Quote:
Originally Posted by pmmunro View Post
This is what electricians are taught these days.

https://www.electricalsafetyfirst.or...actice-guides/

The essential equipment is a suitable voltage indicator and either a know supply or a proving unit. The voltage indicator has to be proved to be working before and after checking circuits are not live. Note that multimeters are not encouraged due to risks associated to their being set to an unsuitable range. Three test to be made on single phase supplies, ten on three phase supplies.

Possesion of a working voltage indicator and proving unit, or a tester with built-in proving is essential to passing the annual assessment by any of the Scheme Providers, NICEIC, SELECT, NAPIT, etc. with whom electricians should be registered.

"Voltsticks" are another questionable type of indicating device. It can be argued they are useful for proving circuits are live, but certainly not that they are dead.

PMM



Yep, proving units and testers only at the "day job". We have some natty Wera blade screwdriver sets that came with neon screwdrivers - these were removed from the sets and put in WEEE waste. You face serious discipline using non accredited equipment on live equipment - and for good reason !
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Old 1st Aug 2019, 7:53 pm   #10
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Default Re: Neon Tester Screwdrivers

One quirk of my voltpen is the LED will fail to light if the live wire in a 2 or 3 core cable is obscured behind the neutral. It's important to move it along the cable in question, whereupon it flashes on and off in sequence with the twist of the conductors. Nowhere in the instructions is this mentioned.

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Old 1st Aug 2019, 11:53 pm   #11
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Default Re: Neon Tester Screwdrivers

My 3 transistor DAV stick does exactly the same when you run it along a flex.
I liberated it from a skip in the 1980s. It was the same skip I liberated lots of valve mono block amplifiers from on another day. I still have four of the amps.

The DAV stick is an early example of a capacitive volt stick built to a circuit like the ones in the electronics magazines with a square hole to shove the 9 volt battery into. A round PP4 was found in it. 20 years later I de canned a 6XAAAA cell PP3 and taped it into a round shape and dug into a box of samples I had that contained of all things some uncrimped PP9 snaps.
It was a quick fun restore and works as well as a modern one.
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Old 2nd Aug 2019, 10:11 am   #12
David G4EBT
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Default Re: Neon Tester Screwdrivers

I use a non-contact tester from Screwfix, which I find very satisfactory.

https://www.screwfix.com/p/lap-ms890...E&gclsrc=aw.ds

When you switch it on the tip glows green to show that it's working, then if you touch the insulated tip on say the screws on a light switch fascia or 13A socket outlet, it will glow red and give an audible warning to show that it's working correctly and the circuit is live. A much better indication than a neon tester which often glow only dimly. With a neon tester our body is of course part of the circuit so the better we are grounded, the more conductive well will be and the brighter the neon will glow. With the neon on a live contact and your other hand on say a copper water pipe, the neon will glow very brightly indeed, but remember that our heart is in the middle, so ventricular fibrillation may arise.

I binned my neon long ago; too young to die - too old for nasty shocks.

'It's Volts that jolts and mills that kills'.
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Old 2nd Aug 2019, 10:51 am   #13
The Philpott
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Default Re: Neon Tester Screwdrivers

I like the sound of that. Note Screwfix also sell a two-pack of a (similar) LAP pen and a 13A socket tester. (Though as bigclive commented once, not all socket testers are equal, so it would need investigating.)

A couple of oblique plus features of the DAV stick- will not end up in the washing machine in your pocket..and unlikely to get stolen.

That being said I think I might hop over to Screwfix soon. You had me with the green 'on' light. Simple idea but the good ones often are!
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Old 2nd Aug 2019, 12:32 pm   #14
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Default Re: Neon Tester Screwdrivers

For a final check I short live and neutral, rather a bang than a coffin anyday!
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Old 2nd Aug 2019, 2:40 pm   #15
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Default Re: Neon Tester Screwdrivers

I used to work with a guy who told me he was working on refurbishing an industrial unit.
The land lord told him that the power was off and that the power panel was ready for stripping out.
He undid the incoming cable and instinctively did not touch any of the wires.
When he got to the stage where the cable needed to be pulled out it let rip.
He never told me if it blew one,two or all three fuses.
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Old 2nd Aug 2019, 4:49 pm   #16
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Default Re: Neon Tester Screwdrivers

I was taught 'All wires are live until _you personally_ have proved they are not' I would never joke about isolating a circuit, but if you are working with me, I would not be insulted if you verified that. In fact I would expect it. Similarly I would hope you would not be insulted if I check the wires were dead. Anyone can make a mistake...

To get back on-topic, my feeling is that neon testers are not themselves dangerous. Misuse of them might be. If I used one to check the status of a wire I would test it before and after on a known live point in the same area (so I would be earthed similarly) to be sure.

And anyone who doesn't know how to use test equipment, including neon testers, safely, is not fit to be called an 'electrician'. So there is no reason not to have one in the toolkit.
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Old 3rd Aug 2019, 2:14 pm   #17
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Default Re: Neon Tester Screwdrivers

I always pull the "big" fuse at the meter, keep it in my pocket until I'm done.
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Old 3rd Aug 2019, 2:21 pm   #18
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Default Re: Neon Tester Screwdrivers

Neon screwdrivers are at least vulnerable to damage and notably unreliable, therefore probably 'not the best option' for testing anything. I agree that non-contact (capacitively coupled) indicators are very useful and would not be without mine, but they too need proving every time. If nothing else, I rub the tip of my voltstick against my shirt sleeve to use triboelectricity to activate it.

In the electrical industry it is common knowledge that only a GS38-compliant voltage indicator should be used to prove a circuit dead. So much so, that electricians decry all other forms of testing and insist that volt-sticks and their ilk are a menace and should be binned. However, a GS38 indicator will not warn that both legs of a circuit are live w.r.t. true earth (only that they are different in potential) or tell anything about a cable mid-span where no connections are accessible. Therefore I use both types of tester in combination, requiring a negative response from both before proceeding.

Having thus gained a considerable amount of experience of the response pattern of the volt-stick, and being able to trace potential gradients to a high degree of spatial precision with it (to the extent of being able to find an incorrect core assignment in a 19-core circular flex without opening the connectors,) I find no further use for neon screwdrivers and do not expect to use one again.
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Old 3rd Aug 2019, 7:14 pm   #19
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Default Re: Neon Tester Screwdrivers

Quote:
Originally Posted by TonyDuell View Post
I was taught 'All wires are live until _you personally_ have proved they are not' I would never joke about isolating a circuit, but if you are working with me, I would not be insulted if you verified that. In fact I would expect it. Similarly I would hope you would not be insulted if I check the wires were dead. Anyone can make a mistake...

Standard procedure is to isolate the mains and lock off. In front of the person who is going to do the work test the tester with the proving unit. Test all phases and neutral with respect to one another and then with respect to earth. Again, check the tester with the proving unit and hand the person doing the job the lock off keys. If the person doing the work wants to double check that's fine.
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Old 4th Aug 2019, 12:13 am   #20
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Default Re: Neon Tester Screwdrivers

During my service career I used to clip a neon tester screwdriver to my top pocket but hanging outside. The constant glow reassured me that the Radar was poking out its usual power level though of course the magnetron whine told me that anyway. The neon glow is probably why I never had anybody come to see me in the Radar compartment. To think I used to sleep there nightly too for 18 months
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