How do these mains electrician's test lights work?

Factual Questions
1

I mean these: Test light - Wikipedia

More specifically, does some current flow through the user’s body to the ground? What if the user is hovering in the air or is in some way insulated, is the light still going to turn on?

2

Per the article you linked to: “A neon lamp takes very little current to light, and thus can use the user’s body capacitance to earth ground to complete the circuit.” So it would seem that if the user is isolated from ground, the lamp won’t light.

3

I’m not sure; however, I just ordered one. It says that they can be used to find bad bulbs on Christmas Tree lights. I sure could have used one of them last month!

4

with the one contact testers you have to be touching a specific spot on the tester for it to work. if you are isolated from the ground (as you should be when working with live electrical mains circuits) you can still be capacitivly coupled to the ground for the tester to work. your body may have enough capacitance for a bit to light the tester even if you weren’t capacitivly coupled to the ground.

5

Note that it says that it uses “body capacitance”, though. Technically speaking, the user is still isolated from ground, in the sense that no electrons will flow through the test lamp and the tester and make it to ground.

6

True, but…

An AC current can flow through a capacitor. So, I don’t consider this “isolation” in a strict sense.

7

Is this true? A capacitor is not an open circuit for AC so if my body is capacitively coupled to the ground then some current should pass through.

Does a test light work with galvanically isolated mains?

8

Just get a non-contact tester. It’s more useful.

9

best thing since sliced bread.

potential lifesavers too.

10

For sure. One must ask the question: do I really want to trust my life to a tester made in a factory with dubious quality control, and which relies on my (however marginally) connecting myself to the source voltage?

11

I use one of these Fluke voltage testers almost every day (including today).

They work well, but I always stick one in a wall socket beforehand to verify it’s working, and many times I’ll verify with a standard VOM if I have any concerns.