Ground
Ground
Well its called touch potential they do that in most power plants they only place i have seen sensors for a fence was a state prison project we did once and that was called a g -line . So my best answer would be if you have a high voltage around its a ground simple as that .
Also the prison had sensors every 10 foot if you applied 50 lbs on that section of fence it set off a alarm turned on the floods on that section only nice and bright the main console had a fence computer graphic screen which then flashed on that 10 foot section . funny but your not getting out 18 foot with razor wire on top in a 4 foot roll then a double fence outside that one 20 foot apart with a five foot deep footer under fence on each . The g- line was if you came near top of fence a magnetic field would pick you up if you were thinking about flying over it .
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