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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 4th Aug 2019, 10:50 am   #21
Julesomega
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Default Re: Neon Tester Screwdrivers

It's always good to hear the advice of professionals so I had a look at electricalsafetyfirst who seem to require either a two-terminal tester made for the purpose or if that's inconvenient a contactless tester.

I'm personally uncomfortable testing between two points with a probe in each hand, but unless there is a suitable terminal for a croc clip that's what you have to do. Worse, how does that work if say your earth circuit has become live?

As Ian says, contactless testers tend to light up if you touch any metal. It makes better sense to have a contactless tester without a blade and I might be tempted next time I'm in Toolstation. I already have an NCV facility on my Uni-Trend UT210E AC/DC Mini Clamp Meter which works ok, the specs says it will detect mains voltage at 15mm from a conductor

To me, a neon tester is the most trustworthy test if you can get someone else to open the breaker and you see the neon go out
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Old 4th Aug 2019, 5:35 pm   #22
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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
That's certainly the case with the buildings/plug socket and light bulb electricians. There is a compounding opinion from organisations when they can't trust that type of electrician on how to use a multimeter.
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Old 4th Aug 2019, 6:49 pm   #23
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Default Re: Neon Tester Screwdrivers

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Originally Posted by ms660 View Post
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.
That they aren't safe for some measurements and under specific circumstances, doesn't mean they're unsafe for all purposes.

Testing for a live chassis is one of the best applications as long as you know what you're doing (always test both plug orientations and interprete unexpected results correctly).
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Old 4th Aug 2019, 7:36 pm   #24
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Default Re: Neon Tester Screwdrivers

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Originally Posted by Maarten View Post
Testing for a live chassis is one of the best applications as long as you know what you're doing (always test both plug orientations and interprete unexpected results correctly).
I did on most occasions, sometimes got a belt though because I forgot to test for live chassis...as always, nature conspires...

Lawrence.
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Old 5th Aug 2019, 2:33 am   #25
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Default Re: Neon Tester Screwdrivers

I guess, in this country, we get a little careless because of our low mains voltage, but I got bit on 240 volts on my industrial electrician's job, derived from three phase mains. It'll stun you pretty good, especially when you when you have a good contact with earth.
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Old 11th Sep 2019, 12:06 am   #26
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Default Re: Neon Tester Screwdrivers

Use a suitable tester ? And then again ,are the leads in date/safe to use. A non screwdriver ( kept in top condition, chuck it id you doubt it's safety) is something I'd sooner trust. As with all go/no go tests, it's safety essential that the equipment is trusted. Why not test the suspect circuit in the on condition. Screwdriver indicates - switch off and test again. Scrwdriver does not indicate- find a known working circuit and test it. I far these days that the Elf ( as in Elf & safety) has addled folks brains and stopped folks thinking about how to be safe ,unless ther's a long list of safety regulations.
And yes- I was qualified and certified in my last employment to work on 650v circuits, although in my GPO/PO carer, I often workd with 1000v AC power feed on CEL and inside ( certified dead) up to 4.5KV submarine power feed terminals.
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Old 16th Nov 2019, 1:56 am   #27
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Default Re: Neon Tester Screwdrivers

Here we use a "Wigger" sort of a solenoid type tester.
I will use a voltmeter, or a plug in unit that shows all wiring is correct by 3 glowing neon bulbs. If one fails to light then there is a wiring problem at the outlet.

Mu old ham buddy was an electrician working for the state. He used to have to find circuits that ran all over and finding the right breaker, in an office full of people prevented him from turning off the mains breaker.
He would just take a light switch and connect a power plug to it, Flipping the switch to "On" would short the hot to the neutral. He'd plug it in and flip the switch. BANG! the breaker would blow. Likely not the safest thing to do, especially if the breaker had fused, but it worked for him. Something I would not want to emulate.
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Old 16th Nov 2019, 11:14 am   #28
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Default Re: Neon Tester Screwdrivers

Hi yesterday i was checking for a fault/conections to a live chasis Hallicrafters s38 radio this thing is lethal switch in the N wire ETC any way the neon lit on the chasis when off , deciding to double check it didnt light what was going on ?
the said new neon screwdriver had gone faulty. Only use for convience test on known live BE 4 and AFTER any test. Mick
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Old 16th Nov 2019, 12:22 pm   #29
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Default Re: Neon Tester Screwdrivers

HI Mick.
I don't know if you have seen this, as this radio is known as the Death Radio.

You will need to follow this advice before any service attempt on the above.
http://www.geojohn.org/Radios/MyRadios/Safety.html

Take care and be carefull.

Gezza123
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Old 16th Nov 2019, 2:40 pm   #30
mickm3for
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Default Re: Neon Tester Screwdrivers

Hi thanks for the warning. I do not like ac/dc sets but this said buy me i think i will use an isolating transformer 240 to 110 volt. To check this i an using my variac but only a matter of time will plug into 240v ? so a tx will prevent this its only low wattage i think 29w so said tx will not be that expensive. i will not use an auto tx. Thanks again for the warning Mick
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Old 16th Nov 2019, 10:36 pm   #31
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Default Re: Neon Tester Screwdrivers

There's two considerations here. Do you use a neon which only needs one hand at the end of a tester connected to what may/may not be a lethal supply. Or use a meter with both hands on either side ( and a path across the heart) overthe voltage .( unless you can secure one terminal to a neutral /earth voltage first) . I was indoctrinated into proving by my ancient uncle a time served electrician, who insisted on only one hand contact . BUT the problem with all test kit ( including the neon ) is lack of proving the tester on a known live circuit first.
me- I'm not an electrician, just a bloke who's worked on ,and been tested on high voltage working methods ( up to 650 v DISTRIBUTION) , up to 1000v Ac ( anyone remember CEL 6 ) and a few UK-other countries submarine cable systems of up to 4500 v.
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Old 17th Nov 2019, 6:46 pm   #32
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Default Re: Neon Tester Screwdrivers

I'd not trust an old-fashioned neon-screwdriver over a modern 'detector pen' such as the Fluke 1AC-II

However one place an old neon-screwdriver _does_ have its uses is in detecting RF parasitic-oscillations in power-amplifiers: you can get a bit of an idea as to whether the oscillations are LF HF or VHF depending on the colour of the glow. [purple means you've probably got a VHF parasitic going on].
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Old 17th Nov 2019, 9:13 pm   #33
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Default Re: Neon Tester Screwdrivers

After my last post I bought a Fluke which were on offer from Toolstation at the time, and it is an absolutely fabulous bit of kit. It will even detect live metalwork within a plugtop or a pattress-mounted socket or lightswitch. It self-tests while you are using it until you switch it off and beeps to confirm it's ok. Live indication is visual and audible. It has auto-shutoff if you forget about it. The quoted sensitivity range is 200-1000V ac.

Non-contact means you can verify continuity of the live conductor in an appliance lead

I see Toolstation have now added a couple of cheaper voltage detectors, and Bangood also have one, but I'd choose the Fluke if I lose mine
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Old 17th Nov 2019, 10:35 pm   #34
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Default Re: Neon Tester Screwdrivers

Quote:
Originally Posted by gezza123 View Post
HI Mick.
I don't know if you have seen this, as this radio is known as the Death Radio.

You will need to follow this advice before any service attempt on the above.
http://www.geojohn.org/Radios/MyRadios/Safety.html

Take care and be carefull.

Gezza123

At least that Death Radio makes an attempt to isolate the metal case.

This set however, well see for yourself!

https://youtu.be/eib6GSYS4CQ?t=229
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Old 19th Nov 2019, 5:56 pm   #35
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Default Re: Neon Tester Screwdrivers

Julian,
I have to admit to being confused as to which, of your many neon testers you show in your first post, is the type to throw away.

The important thing to remember is; always test the circuit first with power ON to prove the tester is working. Then Isolate the circuit and test again to prove it is off.
Always mark the fuse panel to warn others that the circuit is being worked on and not to turn it on.

Mike
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Old 21st Nov 2019, 8:25 pm   #36
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Default Re: Neon Tester Screwdrivers

Many "proper" electricians dislike neon screwdrivers, except perhaps for doing up screws, and many employers in electrical or related trades forbid the use of neon screwdrivers.

However we must not become too paranoid, neon screwdrivers are simple, reasonably safe and reasonably reliable and fine for DIY or similar activities.
Any doubts about reliability may be answered by use of TWO neon screwdrivers, both of which have been proved to light on a known live source before the work.

A great deal depends on the size and complexity of the equipment being worked on the degree of risk.

Examples include; higher risk= high capacity industrial switchgear with a FLC of hundreds of amps and a prospective fault currents of tens of thousands of amps. Significant exposed metalwork that is live in use.
Before working on that, I would want FIRSTLY to observe it being isolated, removal of fuses in the substation for example, or isolation and earthing of the 11Kv into the transformer.
I would also observe that the power goes off ! Did the lights go out ?
THEN I would test with an approved tester, probably more than one tester.

Lower risk; replacing hall light switch for a neighbour. Turn off the main switch on the consumer unit and observe that the lights go out.
Use a neon screwdriver on the switch terminals as a "second line of defence", though in practice on a simple domestic installation, turning off the main switch and observing the lights going out would probably be sufficient.

Both the above are almost certainly the same voltage to earth, but have very different degrees of risk.
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Old 26th Nov 2019, 4:52 pm   #37
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Default Re: Neon Tester Screwdrivers

Quote:
Originally Posted by rambo1152 View Post


At least that Death Radio makes an attempt to isolate the metal case.

This set however, well see for yourself!

https://youtu.be/eib6GSYS4CQ?t=229

Yes it's potentially dangerous, as in only one component needs to fail to make it so, but the guy is being a bit precious. Not to mention that his (presumably high impedance) meter would read mains even if the RF ground capacitor and its discharge resistor were perfectly OK.

Restored correctly with the isolated ground bus genuinely isolated from the chassis / case and the RF grounding capacitor replaced by a suitable value Y-class part it will be safe enough on 120V mains. Maybe add a mains ground to the case just for added belt protection.
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Old 2nd Dec 2019, 7:47 pm   #38
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Default Re: Neon Tester Screwdrivers

When I was sparking I hated neons and loved my voltstick. The primary issue for me with neons is they are passing a small current thru one's body and on more than one occasion got a significant tingle due to a short path to Earth (leaning the arm whose hand is holding the screwdriver on the metalwork of a suspended ceiling for instance). Not dangerous or even painful but very off-putting. Also I seem to have a rather low impedance (changing 8 foot fluorescent tubes always gave me a significant buzz which didn't seem to happen to colleagues).

I used my voltstick all the time, but not as a safety tester. As a non-contact tester a voltstick is so useful for many things. But since it can only prove a positive and not a negative, it was never a means to test if something was safe to touch. Well, most of the time, I risked it for speed sometimes y'know but wouldn't advise anyone to do that.

A test lamp is better than a neon screwdriver, a multimeter is even better. Always of course tested before and after with a known live source. And then first touch with a glancing touch from the back of the hand. Alternatively use a junior member of staff to do the first touch.
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Old 3rd Dec 2019, 5:53 pm   #39
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Default Re: Neon Tester Screwdrivers

Playing devils advocate- it's horses for courses on the safety front.
Neon screw driver - small current through body.
Test lamp -sometimes ( maybe a spark), on leg of the test circuit would ( presumably ) be clamped to earth to leave only one hand holding the live lead to be placed on the circuit under test. Similarly for the meter .
But both the test lamp high side and the meter high side need to be tested for insulation (presumably more than once).
In an ideal situation, where do you stop testing ?
[tongue in cheek]
Give the HSE bods a chance and we'll have a dedicated person in a fireproof suit with half inch thick rubber gloves and a large visor ,equipped with a long very well insulated shorting pole. ( OH ,another requirement for said person would be strong nerves).[/tongue in cheek]
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Old 3rd Dec 2019, 7:27 pm   #40
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Default Re: Neon Tester Screwdrivers

That's it, "Switch off, Isolate, Dump, & Earth"

Otherwise you'll be like the poor technician who returns to an H.V. installation, - from a dentist's appointment, only to find out too late that his colleague has reversed the connections of an inductor/capacitor circuit. Big bang!

Anyone remember the BBC-2 colour test film, circa 1967/8?
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