How does an electric fence work?

An electric fence system consists of an energiser generating regular power impulses and one or several wires transporting the power, and insulated against the ground. The insulation is gained by using plastic insulators, which prevent the power from being branched off into the ground. The fourth component is the earthing of the energiser, which should be placed as deep as possible in the soil, where it is most moist.

When an animal comes into contact with the wire a circuit is closed; ie. the electric current flows through the animal and the soil, back to the energizer. Thus the animal experiences an unpleasant (but harmless) electric shock and backs away. Note that it is not obligatory for a fence to form a ‘loop’, and that electric fencing systems are used for fencing-out as well as fencing-in.



Nature shows us how to do it! A tree spreads its roots to take water and nutrients from the soil – the same is true for the earthing: ideally, it branches off in all directions and is positioned solidly and with safe contact in the soil. When an animal comes into contact with an energised wire, the power flows through the animal’s body into the ground where earthing rods take up the power – like roots take up water – and conduct it back to the energiser where the circuit is closed. If the earthing is poor, the power will ‘trickle away’ into the soil: it does not flow back to the energiser, there is no closed circuit, and the electric fence does not work.


  1. Keep your fence as free from growth as possibleGrowth impairs the output of every commercial appliance and results in increased power consumption, especially with battery-driven appliances.
  2. Make sure the earthing is optimal
    As deep as possible (minimum 1 metre/several earthing rods/moist, overgrown soil)
  3. Do not connect two conductive plastic wires by tying them – use special connectors.
  4. Fence wire/tape/rope must not be broken
  5. Use conductive material having the best possible conductivity (ie. low resistance)
  6. Keep fence wire and earthing rod free from rust
  7. Weather-beaten or nagged insulators are unsuitable (causes a high loss of output)
  8. Ensure connection between the energiser and wire is optimal Use cable resistant to high voltage for underground feeds
  9. With battery-driven energisers, check battery condition regularly
  10. Ensure that each point of the fence is carrying a minimum of 2,000 volts through use of a fence voltage tester. When fencing very sturdy animals we recommend a minimum of 3,000 volts from a energizer of more than 0.5 joule. For safety reasons we recommend, however, not to exceed a discharging energy of 5.0 joules.