Definition of an electric fence.

An electric fence for the purposes of animal control is by definition:

A device called an energizer generates high voltage impulses between its two output terminals. The impulse is very brief and is repeated every 1 to 2 seconds. The fence design is intended to connect the animal to these two output terminals through these fencing wires. When the electrical impulse passes through a muscle in the animal it stimulates the muscle to contract. If you haven't felt an electric fence before, the best description of the feel is like leg cramp but lasting for just a brief moment. By necessity it is very unpleasant so that it provides an effective deterrent when the animal next encounters the fence. The animal remembers the unpleasant experience and avoids touching the wires again. It is NOT injury or damage that produces the discomfort but rather the induced muscle contraction that is unpleasant.

For more in depth info on what electric fence products you will need and how to set up paddocks and other complex electric fence systems download some of the electric fence manuals here.


So your new to electric fencing and planning a electric fence design?

10 basic considerations for planning an electric fence.

Spending the time to understand the principles of electric fencing so you can plan your electric fence to suit your desired purpose can save you time, money and alot of frustration.
Being able to select the right electric fence products, for example a solar electric fence energiser over a mains or battery powered energiser can help you to have your fence work for you, not the other way around.  
For the uninitiated planning an electric fence can be a daunting task due to a lack of understanding of the basic principles of how an electric fence operates and what each electric fence component does.

Firstly what is an electric fence?

This from Australia's Sureguard Electric fence Co.

A device called an energizer generates high voltage impulses between its two output terminals. The impulse is very brief and is repeated every 1 to 2 seconds. The fence design is intended to connect the animal to these two output terminals through these fencing wires. When the electrical impulse passes through a muscle in the animal it stimulates the muscle to contract. If you haven't felt an electric fence before, the best description of the feel is like leg cramp but lasting for just a brief moment. By necessity it is very unpleasant so that it provides an effective deterrent when the animal next encounters the fence. The animal remembers the unpleasant experience and avoids touching the wires again. It is NOT injury or damage that produces the discomfort but rather the induced muscle contraction that is unpleasant.

In Summary:

The animal must be simultaneously connected to the both output terminals of the energizer via the fence wires.
Animals with thicker insulating covering need higher voltages.
The applied voltage must pass through muscles. It is the muscle contraction that is unpleasant.

Unlike humans, most animals are well covered with an electrically insulating surface such as fur, hide, feathers, etc. So, whereas humans can make skin contact and get a shock with a voltage as low as 100 volts, most animals require a higher voltage in order to feel anything. High voltages produce long distance sparks that will jump the air gap over the animal's insulating surface. The higher the voltage the longer the spark. Typical spark lengths are 1mm (0.04") for every 2000 volts.

If you're using a Sureguard energizer this voltage could be as high as 9500 volts which should be able to spark nearly 5mm (0.2"). Importantly, if the electrical impulse does not spark across this gap to the animal's skin then the animal feels NOTHING! Therefore, a higher fence voltage can mean increased reliability or effectiveness for well insulated animals.

It's also important to realize that more voltage does not always mean more discomfort. Perhaps you've experienced a spark from common static electricity? Did you know that such sparks can have voltages of 10, 20 or 30,000 volts! Yet the sensation is generally just a slight pin-prick feel. What's happening here? The nerves on the skin are being stimulated as the electrical discharge dissipates over the surface of the skin. This feels a little unpleasant but nothing like a properly induced muscle contraction from an electric fence. To induce a muscle contraction, you must have a voltage difference across the ends of the muscle. In other words, the electrical impulse has to go through the animal. It also has to go through the animal in such a way that stimulates many muscles in order to make the overall "feel" unpleasant enough.

How can the muscle contraction be made strong so that it provides an effective deterrent? Firstly, the electric fence energizer must be able to generate sufficient electrical energy (energy is measured in joules). Most electric fence energizers will do this. However, this energy must be delivered to the animal with minimal loss between the energizer and the animal.

This from Australian Daken Electric Fencing Manual

ELECTRIC FENCING is an alternative method of fencing which offers you
the following benefits:

1. LOW COST

An electric fence can perform the same task as a conventional fence using much less material.

2. EASY TO BUILD

Lower wire strains and generally lighter construction make much quicker and easier construction, especially in difficult terrain.

3. EXTENDED LIFE

Electric fences are not subjected to the same physical pressure from animals, and can therefore be expected to have a greatly extended service life. The life of old fences can be considerably extended using electric fencing.

4. UNIVERSAL APPLICATION

Electric fencing will contain all types of animals, and is a positive deterrent to wild pigs and kangaroos. Educated stock develop greater respect for electric fencing than for any other type of fence.

5. FLEXIBILITY

There is no quicker or easier way to effectively subdivide a paddock for controlled grazing than with an electric fence.

6. LOW MAINTENANCE

Once your fence is properly installed and your stock are trained, the maintenance requirements of electric fencing are little different from conventional fences.

7. LESS STOCK DAMAGE

The shock from your electric fence causes no physical damage. If your stock are forced through the fence by bushfires or dogs, they are at less risk than with a conventional fence.