While I was replacing a switch, I noticed that my screwdriver tester lit up (it can detect 100V to 240V) when I touched it to the earthing wire. Then by testing the supply with my multimeter I got this result: the ground and neutral wire have no potential difference nor do the live and ground and earth have any potential difference. I must specify here that I have a cheap multimeter that doesn't have LoZ mode hence I wasn't able to make any further diagnosis whether it is ghost voltage. By all this now Iknow that the earthing is not proper but I still want to know what was the reason that the tester detected voltage but multimeter did not?
2
-
I take it your "screwdriver tester" is one where you clip one lead to a ground point and touch the tip to a potentially-energized object to detect voltage?– ThreePhaseEelCommented Apr 26, 2019 at 22:25
-
Yes and the ground point is my finger. The exact structure is given in this Electronics SE answer electronics.stackexchange.com/a/96102– babaCommented Apr 27, 2019 at 10:16
Add a comment
|
1 Answer
Yes.
A "neon screwdriver" has to operate at very low currents for both safety (you don't want to give the user a shock) and functionality (the capacitive coupling between the user and earth may be weak) reasons.
Therefore it can detect voltages that are only weakly coupled, for example by cable capacitance.
