Why does a voltage tester (that looks like a screwdriver) turn on even when you are "heavily" insulated from the ground e.g. sitting on a wooden chair. Is it the result of capacitance between the human body and the ground? (i.e. the body and the ground act as conductors, whereas the insulated gap between them behaves as a dielectric does in a capacitor.) If capacitance can cause the tester to glow, how then do insulated/EH (electrical hazard) safety shoes work? I don't have those shoes yet so didnt get the chance to use a tester while wearing them. But I was wondering why capacitance doesnt cause current to flow through the human body when wearing those shoes?