How to choose your fence energizer?
A fence energizer is essential when it comes to securing animals or protecting crops.
In terms of security, it prevents animals from escaping (horses, cattle, sheep, goats) by keeping them within a safe zone, preventing them from venturing onto roads or neighbors' properties.
Conversely, it also prevents wild animals(wild boar, deer, foxes, rabbits) from entering and destroying crops, vegetable gardens, vineyards or orchards. A properly installed energizer considerably reduces agricultural damage. There's also a random flash against foxes and other nocturnal predators, creating the illusion of movement.
Unlike a rigid fence, the electrifier provides a harmless deterrent effect: the animal receives a brief, unpleasant but non-harmful shock, which discourages it from trying again. Without electrification, animals test or break physical fences more easily, requiring frequent repairs.
1. The basics of electric fencing
An electric fence works by sending brief electrical pulses (not direct current) through a conducting wire.
When an animal touches the wire, it closes the circuit between the wire and earth → it receives a brief, unpleasant but harmless discharge, which deters it from trying again. To install an electric fence you'll need a variety of equipment:
- Electrifier
This is the heart of the system, generating the electrical impulses. Check that the energizer complies with CE and safety standards.
- Conductors
These are the wire, ribbon or cord you choose. They are used to carry the electricity along the fence.
- Insulators
They allow the conductors to be attached to the posts without loss of current.
- Posts
These provide the structure of the fence. They can be made of wood, metal or plastic.
- Ground connections
They are crucial to the efficiency of an electric fence, and complete the electrical circuit. Without proper grounding, your energizer won't work properly. For small fences (<5 km), 1 post of 1m will suffice. For medium-sized fences (between 5 and 15 km), you'll need 2 to 3 posts. For long fences, you should opt for 3 to 5 posts. If your terrain is dry, add 1 to 2 extra posts to avoid loss of current.
- Accessories
Gates, handles, turnbuckles, tension testers, etc. depending on your installation.
2. Power and voltage
Voltage is the electrical force available to pass through air, hair, animal skin, etc. In an electric fence, it is expressed as a voltage. In an electric fence, it is expressed in volts (V) or kilovolts (kV).
A good energizer should deliver at least:
- 2,000 to 4,000 V for domestic animals (horses, dogs, goats),
- 4,000 to 6,000 V for cattle or sheep,
- 7,000 to 10,000 V to repel wild animals such as wild boar.
The longer the wire, the greater the losses or the denser the vegetation, the higher the initial voltage.
Power is expressed in joules (J). It indicates the energy sent in each electrical impulse.
There are two values to watch out for:
o Power stored (joules stored): energy produced by the energizer.
o Power delivered (joules delivered): energy actually sent into the fence (depends on losses, length, etc.).).
Some guidelines:
- <1 J → small animals, small fences (<5 km)
- 1 to 3 J → medium animals, medium fences (5-15 km)
- 3 to 6 J and + → powerful animals, very long fences (>15 km), or areas with heavy vegetation.
A powerful energizer without enough volts will be ineffective, and a very high-voltage energizer without enough joules will quickly stall as soon as there are losses. These 2 criteria are important.
3. Types of power supply available
The mains-powered energizers (230V) are economical and efficient, but require a nearby electrical outlet.
Battery-powered battery-powered energizers (12V) are recommended for isolated areas, but require a well-maintained battery.
Solar-powered solar-powered energizers are ideal for areas without electricity.
4. Length of fence to be electrified
The overall length of the fence has an impact on the choice of energizer. The more vegetation or losses (e.g. grass touching the wire), the more power you need.
The number and type of wires (fine wire, ribbon, cord) depend on the animal to be contained or repelled.
The longer the fence, the more power you need, for example:
- <5 km: small energizer
- 5-15 km: medium
- 15 km: powerful
If you have grass touching the wires, or a fence with losses (poor insulators), plan for extra power.
5. Type of terrain and vegetation
Terrain type and vegetation play a role in the installation of an electric fence.
If your soil is damp or clayey, the impulse will circulate well, and you'll need fewer ground stakes (1 or 2). On the other hand, if the soil is dry, sandy or rocky, you risk losing current, so you'll need to install more ground stakes (spaced 2 to 3m apart). A more powerful energizer may also be useful.
If there's little or no grass touching the wires on your property, you'll have little electrical loss, so you can opt for moderate power.
If your property has a lot of tall grass, scrub or brambles, you'll have a lot of current leakage losses, so you'll need a more powerful energizer to compensate.
It's best to regularly clear the vegetation under the fence and to use wires at a certain height to avoid contact with the grass.
Always oversize your energizer slightly rather than being too tight, as actual conditions (vegetation, humidity, length) will reduce efficiency.
In conclusion, a well-designed electric fence is not a violent barrier, but an intelligent deterrent that respects animals. Careful installation and regular maintenance (vegetation, voltage, posts, connections) will guarantee reliability and prevent breakdowns or accidents. See our article "How to install an electric fence".