A neon will glow with very small amounts of current.
You can wave one near any radio source and its quite likley to light up.
I suspect you simply were seeing capacitive pickup from somewhere -
maybe other mains, maybe local transmitters.
Might be an obvious question - but does the screwdriver have an
internal battery? (Usually a button type inside the transparent
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.
Simon Avery, Dartmoor, UK
uk.d-i-y FAQ: http://www.diyfaq.org.uk /
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.