All About Fence Energisers

The purpose of a fence energiser is to provide safe and reliable power to your fence. Learn about the different types of electric fence energisers available.

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All About

All electric fence energisers provide a high-voltage pulsed electricity supply, typically once every second. This can provide an intense shock in order to teach and train the animal but cause no damage or injury. In Europe there is a safety standard which controls the design of the energiser. EN60335-2-76

Types of Energisers

There are three main types of electric fence energisers: AC-Powered, Battery-Operated and Solar-Powered. The source of power for the energiser to function determines the type of energiser you will be using. Specific situations require different types of electric fence energisers.

– AC mains energisers are powered by the alternating current from a standard mains socket. These electric fence energisers therefore require a source of electric power within 100m of the fence to which they connect. Mains energisers must be kept inside a building or under a suitable shelter. You will then require a length of lead out or undergate cable to run the power from the energiser to the fence - domestic electric cable is not suitable for this application as it is not designed to carry high voltage.

If you have access to a mains supply, then you should look to buy an AC mains energiser as there will be no batteries to re-charge and your energiser will be more secure in a building away from possible animal damage and theft.

Shop for AC-Powered Energisers »

AC Powered Energiser

DC Battery-Operated

- These electric fence energisers are best for using when there is no mains power source nearby. Battery powered energisers come in many sizes. Many battery-powered electric fence energisers operate off a 6, 9 or 12 volt battery: Some can run on 2 D-cell torch batteries while others run on the 12 Volt batteries often used in caravans or boats. Generally speaking, the bigger batteries last longer and can supply more volts.

Battery powered energisers fall into 2 categories :-

Wet Battery Energisers - 12v:

If the fence is moved frequently or is semi-permanent and no mains power is available, then select a 12v energiser together with a 12v, minimum 75 Ampere Hour (Ah)leisure battery. The higer the Ah the longer the period between recharges. Generally, these energisers are more powerful than dry battery versions and can operate longer fences.

Dry Battery Energisers - 6v and 9v:

Dry battery powered energisers are ideal for temporary fencing, particularly strip grazing and short fences. These are lightweight and easy to relocate, require minimum maintenance and generally the batteries last 1 - 6 months before replacements are needed. These batteries are not recgargeable.

A common question asked about battery or DC powered electric fence energisers is: "How often do the batteries need to be recharged?" The answer is: It depends on the type and size of energiser as well as the power use of the energiser. Shop for Battery Operated Energisers »

Battery Powered Energiser


Solar powered electric fence energisers are perfect for fences that are not near a mains socket or other power source and need to remain “live” constantly. Solar powered electric fence energisers usually contain a battery for energy storage. The solar panel collects the energy from the sun and charges the battery.

After several years these batteries will need to be replaced, but they will provide a good charge during their life time with very little maintenance.

Shop for Solar Powered Chargers »

Solar Powered Energiser

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Things to Consider

There are many different styles of electric fence energisers to choose from. For the beginner, there are three things to consider when selecting the right electric fence energiser.

1. What is your power source?

The most common power source is AC, or a standard mains socket in your home. If AC power is an option, it would be recommended over other power sources. The other options, Solar and DC (Battery power), work well for areas with no other power source.

A solar powered electric fence energiser is also battery powered; however, the solar panel in the energiser regularly recharges the battery. DC batteries will need to be charged as the energy is utilised.

2. What is the distance you are fencing?

Do you have a simple flower bed or garden that you are fencing to protect, or do you have 150km of multiple wires you are planning to run? It is usually better to purchase an electric fence energiser that covers more distance than you think you will need. The coverage listed for the energiser is for an electric fence system under "ideal" conditions.

3. What type of animal are you fencing in or out?

Is this for nuisance animals like rabbits and dogs, or for bulls and other livestock? Larger animals or animals with thicker hair/wool may need more power to be trained about the purpose of the electric fence. Smaller animals are more sensitive to shock; however, no commercially made energiser when installed properly will harm a pet or a human.

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Fence Energiser Terminology

Each Fi-Shock® or Rutland™ Electric Fencing energiser is clearly marked to answer those three questions. Other words that are common when talking about electric fence energisers are listed below: 

Volts -

This is the pressure behind the flow of electricity to push the energy along the conductive fence wire ( similar to water pressure). Most energisers produce up to 10,000 volts and about 3,000 volts minimum (measured by a voltmeter designed for electric fencing), is needed at the end of the fence to contain livestock.

Ohms -

This is the measure of resistance, rather like the friction of water running along a hosepipe. Small diameter fence conductors, such as those in poly wires and tape have high resistance and are used for short fences. Large diameter  wire such as 2.5mm high tensile have low resistance and can be many kms long.  Vegetation growth on a fence line acts like a leak in a water pipe and "shorts" the fence to earth, thus reducing its effectiveness.

Joules -

This is the amount of energy available to be pushed down the conductor by the energiser and is the measure of shock felt by the animal. This is rather like cubic capacity or volume. Higher joules mean longer fences.

Amperage -

The measure of electric current and what you feel when you get shocked. The higher the amperage the more intense the shock the animal will feel.

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Expert Tips

Energiser Placement Tips

If you're using an AC mains  energiser, the location should be as close to the power source as possible. Mains energisers must be kept inside a building, in weatherproof housing or under suitable shelter. You will then require a length of lead out or undergate cable to run the power from the energiser to the fence - domestic electric cable is not suitable for this application  as it is not designed to carry high voltage. You will also need another length of lead out or undergate cable to connect the earth stake to the earth terminal on the energiser. The earth stake must be used for the electric fence only and should be placed at least 10m away from any domestic earthing.

All battery / solar energisers are waterproof against rain and snow but they must be hung or mounted off the ground to protect them from water ingress which can be caused if they are left sitting in water on the ground during wet conditions.

Solar energisers should be placed in the best position to receive as much sunlight as possible, and well away from shaded areas.

Never allow the fence wires to come into contact with objects which may conduct the electric charge to earth.

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Proper Grounding

Over 90% of the time when an electric fence is not working it is because the system has not been earthed correctly.

When an animal that is touching the ground also touches the live electric fence, the animal completes the circuit and will feel an electric shock. Birds landing on the wire will not be harmed - they are not completing the circuit since they are not touching the ground while they are on the wire.

When installing an electric fence system, people often make the mistake of connecting the wire to both terminals of the energiser. They connect the fence to one of the terminals on the energiser, run the wire along the length of the fence, and then connect the other end of the wire to the other terminal. It is worth noting that you do not need to make a complete circuit with electric fencing, the earthing system and the animal coming into contact with the live wire complete the circuit. Therefore you can make any configuration with your fence that you want whether it be straight line, L shape, T shape or a whole perimeter loop.

The earth stake must be used for the electric fence only and should be placed at least 10m away from any domestic earthing. The wetter the ground conditions the easier it is to get a good earth, so avoid placing earth stakes under trees or building eaves.

Follow the instructions - they will guide you through the process. One terminal will connect to the fence while the other will connect to the earth stake..

Energisers are electrified and should only be opened by experts.
Never open an energiser that is carrying a charge

Mains energisers must be protected from the weather. Follow the instructions carefully for each fence energiser. All battery / solar energisers are waterproof against rain and snow but they must be hung or mounted off the ground to protect them from water ingress which can be caused if they are left sitting in water on the ground during wet conditions.

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Expert Tips

FAQs about Fi-Shock® Energisers

Q: What is an energiser?

A: The purpose of an energiser is to convert the electrical input to an effective and safe low amp, high voltage for output pulse onto the fence wire.

Q: Which energiser should I use?

A: There are three questions to ask before this question can be answered:

1. Q: What power source do I have?

A: If you can use AC (regular outlet) power, that would be preferred. Other options include DC (Battery powered) or Solar power.

2. Q: What is the perimeter distance?

A: Each Fi-Shock® energiser has clearly marked on it the range of wire that it will electrify. Remember that the range is for one strand of wire, so if multiple strands are being electrified  then more power is needed.

3. Q: What animals are being contained or repelled?

A: Dogs, cats, rabbits etc, are generally very sensitive to electrical fences and thus need a smaller energiser. Larger animals, such as sheep and large livestock need more power to help in the training process.

Q: Do I need to protect the energiser from the weather?

A: Yes. Follow the instruction on each energiser. Solar units obviously need direct sun light and need to face the sun for best results.

Q: What battery should I use for my DC energiser?

A: You need to make sure you put the right voltage battery on the energiser.

An energiser that needs a 4 volt battery cannot use a 6 or 12 volt battery unless specified by the manufacturer. Fi-Shock® recommends using a Leisure battery on 12v energisers for best results.

Q: How often do I need to charge the battery?

A: It depends. Each electric fence energiser is different. How often a battery needs to be charged depends mainly on the size and type of energiser.

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