There has been a few questions in the Chat area as to the use of Filament lamps as test equipment.
Personally I don't really agree with the idea.
I'd sooner use a Solenoid like the Duspol N tester:


And it has a Neon Polarity tester in it.
And when the Solenoid is activated by the black button, it draws 240mA, to discount Ghost Voltages.
I use one of these and it has never failed me yet, even up to 750VDC.

[This message has been edited by Trumpy (edited 03-27-2004).]

[This message has been edited by Trumpy (edited 03-27-2004).]

Good Lord, 8 attempts to get a HTML link to work!
Shocker!.

i'm using a similar one, but mine has an LCD display showing the 3phase ac rotation direction. Solenoid is helpful, as you mentioned the ghost voltages. But mine seems to draw less current, as you can measure phase to ground without tripping a 30mA GFCI.

i once had a line where you couldn't separate on and off condition with the neon lamp screwdriver. the cable was in a plastic conduit parallel with some 20 others for a lenght of ~60ft and collected enough strayfield to light it up in full.

Those neon screwdrivers are excited very easily, not only by 50/60Hz power lines but also by proximity to strong RF fields.

By the way, I heard of a story some time ago of an apprentice who dropped a neon screwdriver into water, then fished it out, shook off the loose drips and put it back in the toolbox. The next guy to use it got quite a shock, as the water had gotten inside and partially shorted the series resistor.

Andy,
I don't need to tell you that these testers are made by Benning in Germany.
The Duspol N is so handy to use while doing LV voltage checks on our HV/LV network here.
I reckon that I should move up to the tester that you were talking about.
I currently use a Seaward Phase Sequence Tester, for 400V PS testing.
For 11kV, I use a Martindale Motor-operated PS unit, this is Hand-held, via IEWP (Bucket Truck, insulated to 150kV).
Above that, I use a PoCo provided Phasing Tester up to 66kV.

Paul,
Sorry to get off topic, there, but I ask this question.
Would you guys actually trust a Filament Lamp-type tester to do Voltage tests, within a Prove-Test-Prove methodology.
Or would you take the Neon route?.

í wouldn't trust a filament.
But the neon screwdriver is also not 100% safe, the lamp or any internal connection can fail making you think the line is dead and zzzzzap.

With a prove-test-prove approach, I would trust a filament lamp to tell me if power is off.

I remember reading back in the 1970s how track inspectors on the London Underground use a box containing 12 filament lamps to check when power is shut off for the night.

Presumably the theory is that so long as at least some of the bulbs light up when connected, then all go out together, it's a pretty good indication that all is safe. It would be most unlikely for several bulbs to all blow simultaneously.