Help & Advice
Having several years experience working in the electric fence industry, we have a good understanding of what any beginner needs to know when setting up an electric fence for the first time (such as post spacing), and how to deal with an electric fence energiser for the first time.
Using our knowledge we have developed a guide to assist in the basic understanding of how an electric fence works. We will take you though basic set-up of the electric fence. We will also guide you through electric fence energiser maintenance and troubleshooting.
If you have any further queries after reviewing our guide please do not hesitate to contact us.
Electric Fence Components
To have a safe and fully functional electric fence you will need several components:
This is the main component of any electric fence.
These units convert the electricity from the mains or battery supply into regular high voltage pulses that travel along the length of the fence.
The type of energiser you need depends on the distance the fence is from your mains supply, the length of the fence, and the type of animal you want to control with the fence.
The Conductor (wire)
You can use various types of wire or conductors for your electric fence. For a permanent set-up steel wire, either single or multi-stranded, is the best option. This wire is strong, durable and highly effective at conducting electricity. Although steel wire is the heaviest and hardest to work with of the options you have available.
An easier and lighter alternative is polywire. This is a UV-stabilised polythene twine with at minimum of three strands of stainless steel wire woven into it. This would be commonly use for temporary, semi-permanent fencing and strip-grazing. Polyrope can be used for a permanent fence set-up.
Polytape is made of polythene strands woven into a ribbon with stainless steel wires. It comes in a wide range of colours and widths. It can be used in both permanent and temporary fencing and is highly visible, although it can be more vulnerable in areas with high winds.
Electrified netting is also an option and is made in a range of mesh sizes for use with different animals. These are usually set up with the horizontal strands being polywire, while the vertical strands are plain polythene. The main uses for this are temporary fences and strip-grazing.
The purpose of insulators is to stop the fence wire from touching the post or stake, so there is no electricity leaking back into the ground.
High quality insulators should dry easily to prevent moisture collecting into nooks and cracks. Otherwise the current would leak in an ‘arc’ which reduces the effectiveness of the fence.
It is also possible to use offset insulators to hold the fence away from the fence posts. This has the benefit of stopping the animals causing damage by biting the posts, leaning or rubbing against the posts. This will add to the life of the fence posts.
To allow any electric fence to work correctly it needs to be properly earthed. To do this an earth stake is inserted into the ground and connected to the energiser.
This ensures the power returns through the ground and back to the energiser whenever an animal completes the circuit when in comes in contact with the fence.
Stakes and Posts
A permanent fence would most commonly be set up using timber fence posts with insulators attached. While a temporary fence would normally use metal or plastic stakes, also having anchor posts at the beginning and corners to take the strain.
Posts and stakes come in different heights and with different spacings to suit which animals or stock the fence will be used to keep.
Electric fence testers can be used to take reading at any point along the fence, this allows you to make sure the the flow of power is steady and constant through the fence. A common style of this would be a lamp tester. This testers work by lighting up small LEDs, the more LEDs that light up the more power is going through the fence.
How An Electric Fence Works
Every electric fence is based around three main components. These components are:
An electric fence energiser (to generate pulses of electrical current),
Fence wire (to conduct the current),
And an earthing system (to return the current back to the energiser).
An electric fence works by sending short, high voltage pulses of electrical current along the fence from the energiser. When an animal touches the fence it closes the circuit and sends the current back to the energiser through the earthing system. This pulse will pass through the animal very quickly, so the animal will only feel a brief shock. This will make the animal move away from the electric fence immediately. The animals will dislike the sensation, deterring them from going near the fence. Most animals will receive a shock within the first week of the fence being erected, and avoid the fence from then onwards. Electrical fencing is the safest and most reliable solution when it comes to securing and keeping your animals or livestock safe.
For the fence itself, several materials can be used. Smooth steel wire is the material most often used for electric fences, ranging from a single fine thin wire to a thicker, high-tensile (HT) wire. Less often, woven wire or barbed wire fences can be electrified, though such practices create a more hazardous fence, particularly if a person or animal becomes caught by the fencing material (electrified barbed wire is illegal in some areas).
Alternatives like synthetic webbing and rope-like fencing materials woven with fine conducting wires (usually of stainless steel) have become available over the last 15 to 20 years, and are particularly useful for areas requiring additional visibility or as temporary fencing. This is commonly know as polywire, rope or tape.
The electrified fence itself must be kept insulated from the earth and from any materials that will conduct electricity and ignite or short out the fence. Fencing must therefore avoid vegetation, and cannot be attached directly to wood or metal posts. Typically, wooden or metal posts are driven into the ground and plastic or porcelain insulators are attached to them, or plastic posts are used. The conducting material is then attached to the posts.
Electric Fence Post Spacing
The number of lines in your electric fence and your electric fence spacing depends on the size and agility of the animals you want to contain or deter. Small and nimble species like rabbits, for instance, need more lines than larger, less agile animals like cattle or horses. You need sufficient lines carefully positioned to maximise contact with an animal’s sensitive nose, and to ensure it can’t dodge underneath or jump over the electric fence.
Below are a series of guides explaining wire heights and post spacings for various animals, for both temporary and permanent electric fencing. We have also included information on the best kinds of wire to use.
Sheep, being naturally well insulated, need multiple lines to ensure they get a shock where they can actually feel it. Three lines is normal for temporary electric fencing; five lines provide more security for permanent electric fences. In the five-wire fence, don’t energise the bottom wire or growing vegetation will cause shorting. The bottom wire is designed to stop animals slipping underneath the fence.
Temporary Electric Fencing spacing for Sheep
Stranded steel or polywire with polystakes or steel stakes
Permanent Electric Fencing spacing for Sheep
High tensile steel wire with timber posts
Cattle are very sensitive to electric fencing, so you can get away with a single line at around 90cm from the ground when strip-grazing dairy cows. However, for herds containing young calves, you will need two lines.
Temporary Electric Fencing spacing for Cattle
Stranded steel wire or polywire with steel or spring steel pigtail stakes
Permanent Electric Fencing for Cattle
High tensile steel wire with timber posts
Pigs, including boars, are very sensitive to electric fencing, and can be effectively controlled with just two lines of wire. However, you’ll need three lines for piglets, and to separate boars in adjacent paddocks.
Note: This is not a fox-proof fence. To protect piglets from predators see our Poultry/Fox Fencing option
Temporary Electric Fencing for Pigs
Stranded steel wire with timber or steel posts
Electric netting is the best temporary option for protecting poultry and piglets and keeping foxes at bay.
Temporary Electric Fencing for Poultry
Permanent Electric Fencing for Poultry
Stranded steel or high tensile steel wire with timber or steel posts
Rabbits, being small and low to the ground, with the ability to both dig or jump, can be difficult to fence. While electrified rabbit netting is suitable for small areas, a four or six-line electric fence will deter them across longer runs. For permanent electric rabbit fencing you will need a section of wire mesh buried down 30 cm into the ground to deter rabbits from digging their way under the fence. The two electric wires will stop them climbing over.
Click here for More information regarding Electric fence spacing
Electric Fence Safety
A well maintained and correctly installed electric fence is safe for humans and animals. However there are several rules that must be adhered to:
- An electric fence must be constructed in a way that is unlikely to lead to the entanglement of animals or persons.
- You should never electrify barbed or razor wire.
- If the electric fence intersects a footpath or highway you must provide a non-electrified gate or stile so the fence can be crossed.
- If the fence is to be installed along a public path or highway warning signs must be displayed at a minimum of 10 metre intervals.
- You must avoid running electric fences parallel with any overhead power or communication lines, as this could cause dangerously high voltage on the fence line.
- If the fence must cross overhead power or communication lines you must do so a right angle and ensure the fence does not exceed the height of two metres.
- You must never use electric fencing where there is likely to be small children or infants.
- You must never use electric fencing anywhere that there is likely to be bare feet on wet ground i.e. near a swimming pool.
- An electric fence should not be supplied power from more than one energiser at any time.
- If setting up more than one electric fence, a minimum of two metres must be given between the fences.
- Each energiser in use should be connected to a separate earth stake. No household wiring or plumbing should ever be used for earthing.
- Connection leads should never be installed within the same conduit as data cables, communication cables or mains supply wiring.
- Lightning strikes are common on electric fences during thunderstorms. This can cause a fire risk and can damage or destroy the energiser. You should disconnect the energiser and stop power going to the fence during these extreme weather conditions.
- If possible an energiser should be installed indoors in a position which is free from any risk of damage.
- If mounted outdoors it should be mounted on a substantial structure in a position free from the risk of mechanical damage.
It can appear to be a daunting task, to locate and fix a fault on your electric fence. Although there are several things that can go wrong with any electric fence, going through them methodically will allow you to find and repair any problems. Starting with the fence energiser the steps below will guide you on how to test your fence set-up.
What you will need
An essential piece of equipment for dealing with a fault on any fence is a Digital Voltmeter/Fence Tester. This will allow you to test the power levels on the fence, and aid in locating areas where there may be problems. Finding a problem on any fence is done by a process of elimination. Working through from the energiser to the earthing, then the cables, and finally the connections and fence line.
Using the voltmeter
- The first step to testing any electric fence is for you to use your Voltmeter to take a reading of the fence line. To do this attach it to the fence line, moving it for laterally to make sure you have good contact, then place the probe into the ground.
- If the fence has a power drop of between 10 – 20% then it is most probably a problem on the fence line and you should check for vegetation touching the line. If it’s a larger drop that would suggest there is a problem with the energiser.
- To locate the fault you should move along the fence taking readings at 100 metre intervals. You will know you are heading in the correct direction of the fault as the voltage will drop by approx 100 volts every 100 metres as you get closer.
To check the energiser the first step to take is to disconnect the earth and fence cables from the terminals, then use a voltmeter in these terminals. A standard reading should be well over 5000 volts, although this can vary so you should consult the instruction booklet for your energiser.
If the reading is under 5000 volts the the fault is with the energiser and this may need replaced.
If there is no voltage you need to check the supply of power to the energiser. On a battery powered energiser you should check the battery is fully charged. On mains powered you should check the fuse and make sure the power supply from the mains is working. If the voltmeter reading is over 5000 volts then the next step is to check the earthing.
The earthing installation being poorly installed is a common cause of low voltage on your electric fence. With up to 80% of all fault being caused by earthing. Ensure that your energisers earth stake is place that isn’t overly dry. I’n the summer moths it may be neccessary to water the area.
The next step of checking your electric fence is to test the connection cables. To do this you need to disconnect the cables form the fence line. Then use the voltmeter to take a reading. You are looking for the reading here to match the earlier reading from the energiser.
Electric Fence Maintenance
The most important time for maintenance and upkeep of an electric is the first week. This is due to the fact that electric fencing works on the ability of the animals to learn. Once they associate touching the fence with an unpleasant shock they will know to avoid it in future. This being the case, it is recommend that in the first week you inspect the fence daily to ensure it is working well. This is so the animals are more likely to receive a shock during the initial learning period. After this you should only need to check the fence once every week or so.
Each time you inspect the fence you should check:
- The connection between the energiser and electric fence.
- The connection between the energiser and the battery (or mains supply). Look for any signs of corrosion or animal interference.
- The connection between the earth rod and the energiser.
- You should walk the length of the fence looking for signs of damage to insulators or ‘arcing’ which could indicate a breakdown of insulation. Other ways of checking for ‘arcing’ would be to listen for a regular click or in low light you may see sparks while the energiser is on.
- Use a fence tester or voltmeter to check the pulse at each end of the electric fence, and on each conductor wire on multi-wire fences.
- In the use of electrified netting you should check the horizontal wire at approximately 100m intervals, and also the connections between separate rolls of netting.
- Finally you need to keep control of weeds and any vegetation as contact with the fence can cause leaks that will reduce the voltage.
Any electric fence can have a number of factors that can cause the diversion or impediment of the flow of electricity. The most common term for these factors is the ‘fence load’.
Of all the factors that can cause a high fence load the most common is vegetation touching the electric fencing. This has the effect of drawing current away and causes the available power to be reduced to the point that the animal may not be given an effective shock. This is why it is essential that any excess vegetation is controlled.
Other contributions to the fence load that you will need to check for are:
- The power of the energiser not being adequate for the fence length.
- Broken or drooping wire.
- Inadequate earthing for the fence
- Poor connections or rusting wire.
- Cracked, damaged or poor quality insulators.
Other consideration that you must take with electric fences is that any of the above problems will be magnified in wet weather. This can lead to all the electricity from the energiser leaking, or being unable to flow through the fence. The term for this is ‘shorting out’.
Frequently Asked Questions
1. What’s the best energiser type for me – battery or mains powered?
Mains powered is the most suitable for a permanent fence that has a mains supply nearby, it can also be housed indoors and a cable can be used to run to the fence. Battery powered is great for temporary fences or where no mains power is available, as they can be kept outdoors.
2. How many posts will I need to use on my fence?
The recommended amount would be an average of one every ten metres. One of the great advantages of an electric fence is that there is much less material required than for a traditional fence, so it’s easy to erect and take down. Insulators are also needed for the wood posts.
3. Is it better that I have a more powerful energiser than I need?
The bigger the output from your energiser, will increase the amount of power needed to run it. This will increase the cost. Although giving yourself some power over what you need, which will be useful if the need arises to increase the length of the fence.
4. There doesn’t seem to be much of a kick off my electric fence?
Any fence should have a minimum of 3000 volts running at any point in the line. Bear in mind that with the animal having possibly a wet nose, bare feet, and standing on wet ground its experience of touching the fence will be different from yours.
5. If I don’t put the fence line in a loop will it still work?
6. Is it a problem if grass/vegetation is making contact with my electric fence?
Yes this will definitely cause problems with your electric fence as anything touching the fence will cause it to ‘leak’ power causing the fence to be less efficient. This includes but is not limited to weeds, wooden posts, barbed wire, branches of bushes, and grass.
7. Why does my electric fence seem to not work as well when the weather is dry?
When the weather has been dry for a while this inevitability causes the soil to dry out. This makes the soil less conductive and reduces its effectiveness. You can combat this by increasing the number of earth stakes and wetting the ground around the earth stakes.
8. Will the electric fence hurt my animals?
No, the energy through the fence is sent in pulses which allows the animal to move away. What the animal experiences is similar to cramp and after touching the fence a few times most animals will learn to avoid the fence.