"Interesting" neon indication.

IIRC you are right. It is practice to throw a an earthed chain over teh cables to be worked on I think.

if you`re working on switchgear, you will have the "hot" stuff usually hidden away behind an interlocked cover with ceramic or shellac`d paper bushings - these bushings are referred to as spouts.

So for a HV circuit breaker, you will normally have six spouts (two per phase) - one on the busbar side and one on the "outgoing" side

Hello Jon

Sorry for late reply, behind again.

Might be an obvious question - but does the screwdriver have an internal battery? (Usually a button type inside the transparent handle).

If so, it's one of those annoying and potentially dangerous "all in one" things that do continuity as well as testing for mains.

I don't recommend 'em for just this problem of false positives.

I have seen this on lighting circuits which include a florescent fitting.

Even when the circuit was isolated from the mains the tester indicated a current present.

More a voltage, really. The current required to light a neon is so small in domestic terms as to be insignificant. That's why they're near useless.