electric fence tester
Maybe you guys know this but i didn't and i grew up on the edge of a rural area.
You can take a long piece of grass or similar weed and strip it down to one main strand. You then hold this strand at one end and place the other end on the fence. Slowly slide the strand inward and you will eventually feel a twitch that will get weaker when you slide your hand away from the fence and stronger when you slide towards it. The length will depend on many things but will atleast let you know if the fence is or isn't working.