How Does an Electric Fence Work?

Electric Fence

Horse behind electric fence

Nowadays, nearly everyone who keeps pasture animals naturally uses an electric fence.

As early as the 1930s, herds were fenced in with electric fences in New Zealand and in the USA. In 1942, Paul Kolb invented the first electric fence device in Germany. The technology continued to evolve, and today there are even solar-powered fence systems and devices with GPS transmitters.

In the beginning, an electric fence consisted of a conductive steel wire. It was quite expensive, very stiff and quite hard to build. Today, fences can be built and repaired much more quickly, easily and cost-effectively with plastic conductor material in the form of wires, ropes and tapes. And in the case of a mobile system, which is used only for the pasture season, you can also quickly dismantle the fence. The current-carrying thin wires are woven into the plastic.

How an Electric Fence Works

The aim of an electric fence is not to inflict pain on the animals, but to create a psychological barrier for the animals. When an animal touches the fence rope or tape, it receives an unpleasant but harmless electric shock. The animal “remembers” the unpleasant shock of the fence and keeps away from it. (Not like we humans 😉

An electric fence consists of the following main components:

The current-generating fence device (A)  

The power supply is connected with the conductive material of the electric fence and the ground (B). It generates regular, short, high-voltage pulses, so that there is a voltage between fence and the groud. The circuit is thus not closed. Only when an animal standing on the ground touches the electric fence is the circuit closed and the current flows through the animal and the earth back to the power supply. The animal perceives this current flow as a short shock.

The current-carrying conductive material (C)

Wires made of stainless steel, tin-plated copper or TriCOND braided into plastic are used as conductors. How well the material conducts the current depends on the resistance of the material (measured in Ω). Thus, there is conductive material that is sufficient for smaller mobile pastures while other conductive material is suitable for electric fences with a length of several kilometers. Conductive material made of plastic is much easier to handle and reduces the risk of injury to animals. The conductive material is usually tightened in several vertical rows, each above another.

Fence Posts and Insulators (D and E):

The fence posts give stability to the fence and hold the conductive material. For the electric fence to work properly, the current must not flow into the ground at any point. Otherwise, the voltage would be gone and the animals would not receive an electric shock. The electric fence would be useless. This means that in the case of fence posts made of conductive material, such as wood or steel, the conductive material should not be attached directly to the post, but fixed by so-called insulators, which insulate the conductive material from the fence post. In the case of plastic fence posts, the conductive material can be attached directly to the post.

The Grounding of the Power Supply (F)

A clean grounding is essential so that the current can flow without extra resistance back to the power supply. The grounding consists of at least one steel grounding rod, which is driven 1m deep into the damp earth. In the case of strong electric fences, three grounding rods are driven into the ground at a distance of 3 m. The earth rods are connected to each other in series and to the grounding connection of the power supply. Lack of grounding is a common cause of improperly functioning electric fences.

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Repairing your Electric Fence — Checklist for Troubleshooting

Despite the careful construction of an electric fence, there are always situations where we have to repair something on the fence. Manual repairs of fence posts, insulators or the conductor material are quite simple to identify and correct, for example, with Litzclip fence connectors.

However, if there is too little or no more voltage on the electric fence (for sensitive animals, it should have at least 2,500 volts, for robust animals at least 4,000 volts), finding the fault is somewhat more difficult. We recommend these four steps:

  1. Test for discharges along the electric fence
  2. Testing the fence energizer
  3. Inspection of the supply line
  4. Grounding test

 

Step 1: Test for Discharge along the Fence Line

Walk along your electric fence and check if there are any visible damages or discharges. These can be caused by:

  • Vegetation or branches that have fallen upon the fence -> remove those
  • Conductor material has contact with the ground -> tighten/ connect
  • Cut through insulators -> replace with new insulators
  • Broken metal conductor wires -> exchange the conductor material
  • Knotted conductor material -> replace with stainless steel connector

Another possibility is to improve the conductivity of your pasture fence by connecting the conductor material perpendicularly to each other every 200m.

 

Step 2: Check the Fence Energizer

If no external influences are obvious, check the fence energizer. For this, you disconnect the fence connection from the turned-off energizer, but not the ground connection! Switch on the device and check with the help of a fence tester whether the output voltage of the fence energizer is over 6,000V. If so, you can reconnect the device to the fence and continue with step 3. If not, check the power supply of the energizer. You may need to recharge the 12V battery, replace the 9V battery or have the 230V supply checked by a specialist. A red flashing or non-lit LED on the energizer gives you a hint for an existing problem. If the power supply of the device appears to be ok, call for service!

 

Step 3: Inspection of the Supply Line

If the cause of the fault is not found in the fence energizer, check the supply line to the fence. For this, you measure the fence voltage at the end of the supply line. You should be able to measure at least 6,000 Volt here as well. If this is the case, the supply line is also intact and you continue with step 4. If the voltage is below 6,000 volts, the fence cable is disturbed. In case of an underground supply line, there may be damage to the underground cable. Make sure that you use a suitable high-voltage underground cable! In the case of an overground supply line, there may be discharges somewhere between the fence energizer and the electric fence: Does the supply line have contact with the building? For example, through ivy or bushes or at a gutter? If so, remove the cause of the discharge, if not, proceed to step 4.

 

Step 4: Check of the grounding

For testing the grounding, you must first short-circuit the fence wire at a distance of about 10 m from the grounding with the help of iron rods. Then, you can check the voltage directly at the grounding post using a digital voltmeter. If the voltage is above 1,000 volts, improve the grounding and pay attention to these points:

If the voltage at the earth rod is below 1,000 volts, the grounding is all right and the fault must be somewhere in the fence system. Go back to step 1 and check whether there is, for example, a broken insulator after all. Then check the fence tension again with a fence tester.

We hope that with this guide you will be able to find and fix the problem in your electric fence.

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How you build a reliable electric fence

For your animals` safety and health, a well-functioning electrical fence is a prerequisite. All components must be carefully coordinated with each other. If you keep in mind the following points during planning and maintenance, you can be sure to rely on your electric pasture fence. Read more

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Conductive Materials for the Electric Fence: The Polyrope

Deciding which conductive material is most suitable for your electric fence is not always easy. In another blog post, we’ve given tips for the use and purchase of polytape and polywire. In this blog post we’ll talk about when one should use polyrope, and offer some advice for the right choice from the various types of ropes. Read more

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Conductive Materials for the Electric Fence: The Polywire

In the other two parts of our series on conductive material, we give tips for the use of Polytape and Polyrope. In the following, we discuss the third option of fencing your pasture: Polywire. Read more

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Electric Fence Equipment – 6 Products that Make Your Life Easier

In this blogpost, we present several clever products of electric fence equipment, which will make your life as an electric fence owner easier:

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Prevent your foals from being hurt by the fence

In order for a foal to develop healthy, it should stay on a pasture at an early stage. Even if foals look quite fragile at first, the owner is well advised to let them roam onto the pasture – despite the dangers. After all, horses have a strong need for movement. Read more

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Conductive Materials for the Electric Fence: The Polytape

One of the most important decisions when designing a pasture fence is the choice of the suitable conductive material. You can choose between Polyrope, Polywire, and Polytape. In these plastic conductive materials, the conductive wires (e.g., Niro or copper wires) are woven into non-conductive plastic threads. Thus they are flexible to use, very light and easy to assemble or to dismantle. Read more

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How to Fill the Dry Battery of your Electric Fence Energizer

One integral part of maintaining your electric fence is, of course, the maintenance of the associated battery. Before we explain how acid batteries are filled, let us briefly review the different terms of battery types. Read more

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DIY: How to Winterize your electric fence battery

Who is not familiar with the following situation? The first few cold days of the year – and your car is already struggling to start in the morning. Yes, when it comes to batteries, winter makes its own rules. What might seem like a cruel joke being played by Old Man Winter or Jack Frost is actually just simple science. Due to low temperatures, the chemical reactions within the battery are slow and therefore performance is limited. So, old, worn out batteries that have seen better days may stop working as temperatures drop. But what does this mean for your electric fence battery? Read more

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