No earthing, no pulse
An electric fence performs its function through the deterrent effect of electrical pulses. The fence itself provides only a limited mechanical barrier. It is therefore essential to inspect the fence to ensure that it functions correctly and operates safely. Although it is an inconspicuous component, earthing plays an extremely important role in an electric fencing system. Only correct earthing ensures reliable containment and protection against intruders.
Correct earthing is the most important prerequisite for ensuring reliable containment and allowing the energiser to deliver its full output to the fence. The fence system is an electrical circuit through which current flows. IMPORTANT: The fence does not have to form a closed loop to complete the circuit. Instead, the circuit is completed when an animal touches the fence. The current therefore flows from the energiser through the conductors and the animal's body (or vegetation), through the ground and the earth stakes, and back to the energiser. If the earthing is inadequate, less current flows and the deterrent effect on the animal is reduced. The risk is that the animal may escape or enter an area from which it should be excluded.
Only correctly installed earthing completes the circuit and makes the fence effective
2. What should be considered with regard to soil conditions?
The soil can create very high electrical resistance and significantly impair the reliable containment provided by the electric fencing system. The aim is to minimise soil resistance by ensuring good soil conductivity. Moist soil with a good grass cover promotes conductivity, whereas dry soil with sparse vegetation makes effective earthing difficult. Challenging weather conditions, such as a layer of snow or frost, can also severely impair the earthing. On sandy ground, it is advisable to run an exposed, uninsulated earth conductor along the fence and connect it to earth at regular intervals. The poorer the soil conductivity, the more earth stakes should be used.
3. How do you earth an electric fence correctly?
One or more earth stakes are driven at least 1 m into the ground until they reach moist soil. If several earth stakes are used, space them 3 m apart. The earth stakes are then connected to the energiser using high-voltage and connection cables. The number and depth of the earth stakes are crucial: the more stakes are used and the deeper they are driven, the better.
IMPORTANT: Use only galvanised, rust-resistant materials for earthing, as a layer of rust significantly reduces its effectiveness.
Earth stakes should be driven approximately 1 m into the ground
Where soil conditions are unfavourable and/or the fence is long, several earth stakes are advisable
4. How is the earthing checked?
The reliability of the earthing should be checked when the electric fence is put back into operation in spring, during dry periods in summer, whenever the fence malfunctions, and after a new energiser has been installed. Use suitable measuring devices or fence testers for this purpose. Carry out the test as follows: create a short circuit by placing iron stakes in contact with the live conductor approximately 100 m from the energiser. Ensure good contact with the conductor and drive the stake at least 30 cm into the ground. The fence voltage should now fall to 2,000 V (or 1,000 V in dry soil).
Insert the voltmeter's earth probe into the ground approximately 1 m from the last earth stake connected to the energiser and hold the measuring contact against this earth stake. The reading should be below 1,000 V. Remember: the lower the reading, the better. As a general rule, inspect your fence system and check on your animals every day. Written records help demonstrate that these checks have been carried out.
5. Which safety regulations must be observed?
When earthing the energiser, maintain a minimum distance of 10 m from other earthing systems (e.g. a building earthing system) to prevent voltage flashover, for example in the event of a lightning strike. This safety distance is important to protect the building's earthing system, including its water pipes and electrical wiring. The energiser's earthing system and the lightning protection system should also be at least 10 m apart.
Excessive voltage, such as that caused by a lightning strike, can destroy the energiser. The fence will then cease to function and the animal may escape. To prevent this, a lightning protection system should be installed between the energiser and the fence system. This is mandatory when the energiser is installed inside a building and recommended when it is installed outdoors.
This is particularly advisable when using a mains energiser, as the surge can be transferred to the mains electricity supply. A so-called lightning protection choke effectively protects the energiser against damage caused by lightning strikes and excessive voltage.
A lightning protection choke effectively protects the energiser against damage caused by lightning strikes and excessive voltage
