Electrical screwdrivers

Yup. I've got one of those table lamps which turn on when you touch the metalwork, and that lights a neon screwdriver dimly, showing that they put mains (or near mains) voltage through you. Real electricians dislike them as they respond to leakage currents.

Yes it is. It's voltage produced by stray capacitance, not inductance.

NT

Yes. They are and can only be a rough guide. My old Neon one when I could see could light up if you just laid a wire alongside where a mains cable went. I imagine the newer kind use some kind of fet and an led to do the same job, but either way, I'd not want to trust on myself. The only use I ever found for them was as a confidence check that an appliance was absolutely dead and disconnected. Anything involving runs of wire will be very ambiguous. Brian

Assuming you mean a *neon* screwdriver, yes it is not uncommon, although with experience you can usually differentiate between a "true" and a "false" live, the latter lights the neon more faintly and sometimes there is some flickering.

A useful tool in sufficiently skilled hands. The "volt stick" is also very useful in diagnosis since it will sense live through insulation, but some also seem to show false positives, and others can be a bit low on sensitivity.

Depends on the 'electric screwdriver'- they are not the most 'reliable' or safe items. As you surmise, they can detect 'stray' fields / currents and give misleading results.