Electric Fencing For Dummies

There are a lot of things that look complicated but one does not dare to ask others since one is supposed to know! You know the feeling! Electric fencing is one of them.

WHY WOULD I USE ELECTRIC FENCING?

By nature, animals that you have in the paddock like to rub on fences which can do a lot of damage to the fences as well as to animals, especially if the present fence has barbed wire on top. If you electrify your fences you keep your animals away from posts and wires and prolong their lifetime. At the same time, you put up a barrier that animals soon learn to respect. In other words, electric fencing not only keeps your animals within the boundaries where they are supposed to be, but also protects your fences from damage. Electric fencing is also the answer for areas where temporary fences are required i.e. shelterbelts, strip grazing, dam protection etc.

HOW DOES IT WORK?

The principle is quite simple. Just imagine a broken circle. When you close it, you get “snapped”.

In other words, you attach the positive terminal of your energizer (+) with an insulated lead to the fence you want hot. Then attach the negative terminal (-) which is on the other side of the broken circle to the earth. The earth may consist of one, two, three or more galvanised pipes or rods that are approx. 2 m long, at least 3 metres apart and have been hammered into the ground in a straight line. The best earthing is achieved in a permanently damp area, the “wetter the better”.

Over 90% of all failures of an electric fencing system can be traced back to poor “grounding” or “earthing”. If an animal stands on the ground and touches the hot wire it closes the circuit and gets “snapped”. However, a bird that is sitting on the hot wire does not feel anything because it does not close the circle.

INSULATORS

All wires you want “hot” must be properly insulated. In other words, the hot wire must not be in contact with the ground through battens, posts, waratahs or for that matter any uprights. This would close the circle and “short the fence out”. When it rains wood posts or battens get soggy and become conductive. Waratahs are conductive at all times. Therefore, plastic insulators are used to keep the hot wire away from any possible contact with the ground and at a reasonable distance from the posts to avoid arcing.

HOW DO I GO ABOUT IT?

There are two possibilities:

• You can electrify an existing fence by adding one or several permanent hot wires or
• You can add hot wires when you put up a new fence

In both cases, you save a considerable amount of money. A permanent fence may no longer be strong enough to keep the animals within the boundaries. However, an electric wire or two will keep them at a distance – especially if you use outrigger insulators – and no pressure is put anymore on the old fence. It will last for another few years or even longer.

If you put up a new fence you can use posts every 6 – 8 meters; no battens are required. You only need to strain the wires about half as tight as you would normally do. Three to four hot wires are recommended for cattle, and five to six for sheep. In case they get cunning and jump through the fence – which would not close the circle and, therefore, would not ”snap” them – you have to resort to a system that has alternate “live” and earth wires. In other words the top, middle and bottom wires are hot, and the second and fourth are neutral. If an animal touches both wires it closes the circle. This system is a bit hard on dogs because they have to jump over the fence and can no longer go through them. It is also an excellent system in case earthing your unit is difficult due to too dry soil or rocky or stony ground.

TYPES OF ENERGISERS

There are basically two types of energizers:

Mains powered units are plugged into a 240 V socket. They are certainly more economical than the next class of energizers.

Battery-powered units are driven by either battery that is replaced periodically, or by a marine battery (Deep Cycle). However, they have to be charged which is done in two different ways:

• With a battery charger means you require two batteries (one to be charged and the other one “working”)
• With a solar panel set up that charges the battery continuously during daylight.