My fence tester (some call them a "fault finder") has a probe on one end that is inserted into the ground. The other has a stub that touches the hot wire. The tester measures the voltage going through the system.
A less painful way to test it (the old school way we did it before testers were around) was to take an insulated object, like plastic handled screwdriver. Holding the plastic part in your hand.......press metal shaft of the screwdriver against a metal grounded object......like a steel T post stuck in the ground......the move the tip of the screwdriver over to the wire. As the gap closes to about 1mm or so, a hot fence will induce a spark to jump the gap. Essentially, make yourself a spark plug. If it is sparking, it is going to hurt!
As for touching it, I would encourage any non-believers in the effectiveness of and E fence to touch a hot fence.....just walk up and grab it so you know what the sensation is. Unless you have a pacemaker, weak heart or something, it won't do permanent damage. You really should try it.....at least twice, maybe three or four times. Better yet, hang on and see how many jolts you can take in a row. My personal best was four times.

A less painful way to test it (the old school way we did it before testers were around) was to take an insulated object, like plastic handled screwdriver. Holding the plastic part in your hand.......press metal shaft of the screwdriver against a metal grounded object......like a steel T post stuck in the ground......the move the tip of the screwdriver over to the wire. As the gap closes to about 1mm or so, a hot fence will induce a spark to jump the gap. Essentially, make yourself a spark plug. If it is sparking, it is going to hurt!
As for touching it, I would encourage any non-believers in the effectiveness of and E fence to touch a hot fence.....just walk up and grab it so you know what the sensation is. Unless you have a pacemaker, weak heart or something, it won't do permanent damage. You really should try it.....at least twice, maybe three or four times. Better yet, hang on and see how many jolts you can take in a row. My personal best was four times.