Electric fencing buying guide

An electric fence is made up of four parts all of which are essential for operation:

1. An energiser which generates electrical pulses.

2. Conductors (wire, rope, netting, etc.) which mark out the boundary for the animals.

3. Posts and isolators to prevent current leakage to the ground.

4. A ground stake or spike.

These components can be purchased individually or as part of an electric fence kit. Either way, it's important to be aware of a few essential parameters before you make your choice.

The energiser is the most important component of electric fences. It works to transform low voltage electrical current (220, 12 or 9 volts) to a high voltage current with very low current.

You therefore need to take great care when choosing an energiser. Energisers are defined by two main ratings:

• output energy;

• output voltage.

Output energy in joules (J)

The output power or power of an energiser is the maximum amount of energy that it can deliver to the conductive material that makes up the fence. This value is measured in joules (J). The stronger the pulse, the more powerful the electric shock.

When purchasing an energiser, don't rely purely on the length recommended by the manufacturer. Instead, look at the output energy rating in joules.

Output voltage in volts (V)

This rating is given in volts (V). The energiser is designed to produce short pulses using high voltage. While a minimum voltage of 2500 volts is required, 4000 volts is usually recommended in practice.

There are four key criteria to study when purchasing an energiser.

1. How much power do you need for your animals?

Some animals (such as horses, cows, dogs and cats) are easier to contain than others (such as sheep, goats, chickens and wildlife).

Low power: for animals that are easy to keep in/out

Electric fences with low energy ratings (under 0.5 joules) are designed for animals that are easy to contain and small perimeter fences with little or no surrounding vegetation.

Medium power: for animals that are harder to keep in/out

Electric fences with a medium energy ratings (1 to 5 joules) are suitable for animals that are more difficult to contain and mid-sized enclosures with an average amount of surrounding vegetation.

High power: for animals in large enclosures

Electric fences with strong pulses (5 joules and above) have been designed to contain animals in large enclosures.

2. The length of the electric fence

The perimeter of the fence refers to the basic length of the installation and not the total length of the conductive material. Systems with multiple lines are able to transport current better over the same distance as long as the wires are linked at regular intervals (at least every 200 metres).

You will need 1 joule per mile of fence and at least 3000 volts from one end to the other.

3. Amount of surrounding vegetation

The denser the surrounding vegetation (e.g. tree branches or grass that come into contact with the fence),the higher the voltage required. Any plants that touch the conductor will lead the current back to earth reducing the power of the electrical pulses. It's important to note that manufacturers generally don't mention this parameter.

4. Type of power source

Energisers that run on mains power are more powerful and more cost-effective than battery-operated models. If you don't have access to mains power, you can use a 12 V battery but you will have to charge it regularly. A solar panel can be used to provide cost-free energy when the sun is shining.

It is also possible to find models that run on 9 volt non-rechargeable batteries. While these models are easy to use, they are the most expensive to run and offer limited power.

Electric fence conductors come in rolls of varying lengths (200 m, 400 m, 1000 m, and so on).

How to choose an electric fence conductor

Conductivity: an essential factor

Copper yields the best performance in terms of conductivity. Stainless steel wires are more durable but provide inferior performance. Most conductors use a mix of both copper and stainless steel.

Generally speaking, conductive wires are described in terms of electrical resistance which is measured in ohms. This should be as low as possible and this is particularly important for long fences.

Electric fence visibility: protect your animals

Coloured lines (white, brown, green, yellow, orange, blue, etc.) make it easier for animals to see the boundary. This should help to reduce accidental shocks and limit stress.

Advantages and disadvantages of different conductors

The fence posts that support the conductive material can be made of wood, metal or PVC. Acacia wood is a great option as it is environmentally friendly, low cost and highly durable. Metal posts are more expensive. Corner posts need to be larger than those covering the length of the enclosure.

Special isolators have been designed with each type of post and conductor in mind. Avoid so-called multipurpose isolators. Isolators must not feature sharp edges or you risk wearing down the conductor prematurely.

The best isolators are made of polyamide. Black offers better UV resistance.

Some electric fence accessories are just as important as the main components. These accessories have usually been designed to help you set up electric fences easily and safely. Here are a few of the most common accessories and their uses:

Fence post drivers for easy installation

Fence post drivers are used to drive posts into the ground effortlessly. Basically a metal cap with handles, a post driver is designed to be lifted and banged down on the fence post to drive it into the ground.

Tensioners: for a well-tensioned fence

Electric fence tensioners are used to apply the right tension to electric fences. Designed for larger wire fences, tensioners are used to link lines or fit them to posts safely.

Rotating tensioners for smaller wires

Designed thinner wire, rotating tensioners are made up of two brackets held in a rotating cylinder. The wires are held inside the tensioner and tightened when the device is turned.

Electric fence reels: for easy winding and unwinding

Electric fence reels help you to wind and unwind the conductive material evenly and prevent knots. They usually feature a crank handle for ease of use.

Gate handles: for easy access

These insulated handles are used to create a passage in the circuit to cross from one side of the fence to the other. They are mounted with a spring which may or may not be supplied with the handle.

Cut-out switch: to isolate a section of fence

A cut-out or isolating switch allows you to divide your fence into sections meaning you can work on one section without turning the energiser off.

Electric fence tester: to check your voltage

Able to test voltage up to 6000 V, electric fence testers are designed to check the voltage all around the enclosure. These devices usually run on batteries.

Connector clamps: for easy line connections

These conductive connectors are designed to clamp at two points in order to link electrical wires together. Simply position the lines between the plates of the clamp and tighten.

Warning signs: to avoid accidents

Safety signs are used to alert people to the presence of an electric fence. These signs must be clearly visible to neighbours and passers-by.

Electric fences are usually earthed by one or several galvanised metal spikes or stakes. It is important that these rods be free of rust and paint as both will act as isolators.

The high voltage delivered by energisers means that they need to be connected using special high voltage lines. Most importantly, the conductive material needs to be made from the same metal as the earthing stakes whether this is steel or aluminium.