hope this helps - - - The tennis balls act as insulators and spacers, the belting works as an insulator as well. The only thing these do not hold up to is a wife with a lawn mower! I put 3 wires on the belt and it seems to work for cows, horses, hogs and dogs. After they are used to it you can go to 1 wire and for short periods of time you can just lay a belt on the ground and the will respect it!
I just screwed a 2X6 at each end to hold insulators - - - the wire does not have to be very tight as the space between balls is short.
I tie the end of the belt to the fence post so that I can disconnect and pull the belt out of the way when I grade the driveway. These might work without the tennis balls but I feel the visibility of the balls gets the attention of livestock.