and might even get you killed or severely injured by giving a false indication of no voltage.
The stick and those lethal "neon screwdrivers" give an indication of the difference in voltage between your body's potential and the potential of the thing being tested. They rely on your body being close to earth potential. But your body's potential can be altered by capacitive coupling to nearby cables and /or equipment and could have the same potential as the live wires. (this capacitive coupled charge on your body is harmless as it is like the static electricity that gives you a shock when you touch something earthed ). BUT if your body's potential is close to live when you use the stick or neon driver then there is very little difference between you and the thing you are testing. The stick or neon driver will see little difference and NOT light and you assume the wire is dead, it isn't.
That volt stick will tell you nothing useful. I have seen them not indicate when there is a lethal voltage present and indicate when there is not voltage present at all.
Yes I agree, it does not help that professional electrical measurement companies such as Fluke offer versions of them. When I meet builders or kitchen fitters on site they always defend use of them by say oh the cheap ones are dangerous but I've got a fluke one or a Kewtech one. Worse still are the ones that purport to tell what voltage is present, they really do give a false reassurance.
As for faultfinding with one well that is a joke. If you are trying to pin down where fault lies the last thing you need is to employ an instrument with the flaws that you have so graphically illustrated above, what a waste of time.
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