Here in the Netherlands electricians are not allowed to use and trust this, most electricians from last 10 years don’t have this in their toolbox, guys like me from old days still have it but don’t use it anymore either, we mostly grab one of those “voltsticks” but even that is not allowed to make sure if there is electricity, according NEN3140 (Dutch norm) we need to use dual pole tester (Duspol), I know this is going to sound stupid but before we test we need to make sure dual pole tester is working on another source and then test the installation we need to work on and after that we need to test dual pole tester again on another source, and guess how many electricians do that.