Following an episode of depriving three flats of mains power for 8 hours I
thought I'd buy some of those cheap volt sticks mentioned here recently.

Seem to work fine on ordinary cable but not on my armoured incomer. I
suppose I shouldn't be surprised by this but clearly they're not gonna stop
me drilling into another armoured cable. ;-)

Out of interest, would the type of armour make a difference (say steel
versus copper)?

Tim