Fencers tend to use too many posts, which likely stems from people's experience with barbed wire, where the rule of thumb was 1 post every rod length (16.5 feet). How to fix it: In an electric-fencing system, Derynck reccomends fence post spacing 80-100 feet apart, or about 50 posts per mile. He suggests using a “stay” – a shorter post that sits on top of the ground and holds wires up – if posts are spaced 100 ft. apart.