At their best, electric fences are inexpensive, effective, and flexible. They can make permanent boundaries around or within a property. Electric fences can also be set up on a short-term basis to protect special crops or vulnerable animals, and they can also be used to create rotational grazing systems to maximize pasture yield.
Fences work in three main ways. They may be physical barriers, psychological barriers, or pain barriers. Physical barriers restrain animals by being difficult to cross. Psychological barriers make animals think they can’t be crossed. Pain barriers make an animal so uncomfortable that they stop rather than push past the fence.
Traditional fences are physical barriers. They are made with wood and wire that is difficult to cross. These fences are too high jumped or climbed, lack spaces to crawl through or under, and are strong enough that they can’t be knocked down or moved aside.
Psychological barriers are fences that work because animals think they will work. One example of a psychological barrier is a cattle guard across the road. The cattle don’t see a way to walk across the pipe bars, so they don’t cross.
Electric fences serve as pain barriers. When an animal tries to cross the fence, it gets a short, hard shock. The animal doesn’t try to cross again because of the pain. Once the pain is established in an animal’s mind, electric fences eventually become a psychological barrier as well. Some animals won’t cross a spot where an electric fence was, even if the fence is gone.
How Electric Fences Work
Electric fences must be properly set up to work as a pain barrier. All the components must be in good working order, free of short circuits, and connected properly. When the fence is set up correctly, the “hot” wire carries electric current from the energizer to the animal. The animal carries the current to the ground and back to the energizer. Carrying the current causes a shock to the animal.
When set up wrong, the fence doesn’t contain livestock and becomes a maintenance headache. Animals will frequently walk through fences with weak charge, damaging the fence and requiring time to repair.
You can see an overview of an electric fence setup here.
Parts of an Electric Fence
There are three parts to a good electric fence. The most obvious is the fence itself—the wires and posts that make up the barrier. The second part is the energizer, which feeds power into the fence.
The final component is the grounding. The grounding connects the current from the hot wire back to the energizer. The key to making any electric fence work is getting power from the energizer through the wires to the animal and back to the energizer.
Types of Electric Fences
The fence itself can be permanent, semi-permanent, or temporary. Permanent fences stay in place for years. These are best for perimeter fencing or protecting areas with a fixed use. Orchards and long-term gardens are best protected by permanent fencing.
Permanent fencing costs the most and takes the most work to install. Permanent fencing can also serve as a physical barrier, although it is not usually as strong as traditional wire fencing.
Semi-permanent fencing stays in place for a season or two. It is good for protecting a garden that won’t stay in the same place every year. It is also useful for protecting crops that are attractive in the short-term, but don’t need a permanent fence. Semi-permanent fencing is intermediate in cost and effort.
Temporary fences are put up and taken down in a matter of weeks or even days. These fences are cheap and easy to put up, take down, and move around. Temporary fences are also the weakest of electric fences. If there is a short, animals can (and will) walk right through them. These fences often consist of only a single wire and lightweight posts.
Building any type of electric fence can be broken into three phases: setting up the fence line, setting up the energizer, and grounding the fence. The steps to follow for setting up the fence line will vary based on the type of fence. The energizer and ground rod setup are the same.
Building a Permanent Fence
Permanent fences are made with wooden and heavy fiberglass posts along with sturdy wire. These fences often use high-tensile steel wire that is an effective physical barrier as well. The posts don’t need to be as sturdy as the posts for a traditional wire fence, but they are still strong.
Step 1. Measure carefully for your permanent fence. You can use a measuring tape for small areas. Use a land wheel, count paces, or use online tools for longer fences.
If you are building lots of fence, it’s important to buy the right quantities of material so you don’t run out or waste money.
Step 2. Start by building corner braces. The corners of a permanent electric fence should be made from H-braces using wooden posts at least four inches in diameter. H-braces use three posts in the shape of the letter H to reinforce the end of the fence against sagging.
Two posts are set deep in the ground with a third held horizontal between them. The fence wire is connected to the rear post and stretched tight. The double posts resist leaning much better than a single post.
Learn more about H-braces here:
Step 3. Set the line posts. Line posts for a permanent electric fence should be made of wood or fiberglass. Wood posts should be at least two inches in diameter, while fiberglass posts should be at least 7/8 inch in diameter.
Spacing for these posts can be wider than for a traditional fence because the wire is lighter. Fiberglass posts can be driven into the ground. Wooden posts may require digging post holes.
Step 4. String the fence wire. The hot wire carrying current should be roughly nose height for the animals you are containing. Clip the wire to the posts using the correct clips. Fiberglass and wood posts may have holes pre-drilled for clips, or you may use spring clips that fit around the posts.
Step 5. Stretch the wire tight using a come-along or fence stretcher. Once the wire is clipped to the posts and stretched tight, you are ready to connect the energizer.
Using Steel Posts
Steel posts are not a good choice any electric fence because they can cause short circuits. The wire touching just one steel post will eliminate the electric current from the entire fence.
If you are buying posts, don’t buy steel. If you have an existing fence with steel posts, there are ways to insulate steel posts. The most common is to use clip-on insulators for line posts and round corner insulators for corner posts.
Barbed Wire and Electricity
Don’t use barbed wire for an electric fence, and don’t electrify an existing barbed wire fence. Electrified barbed wire is dangerous. When the electric current passes through an animal (or a homesteader) touching the fence, there is an involuntary jerk of the muscles.
If you are caught on a barb and this happens, you can get a very nasty gash. There is also the possibility of getting tangled in the barbs and being unable to get free. Being tangled in electrified barbed wire is even worse than getting a single gash—never electrify barbed wire.
Setting Up Semi-Permanent Fence
Semi-permanent fencing usually uses smaller fiberglass posts with poly tape. Poly tape is plastic thread woven into a ribbon. This product is available in a range of widths from ½ inch all the way up to 1 ½ inch. There are fine wires woven into the tape that carry the current through the tape.
Since it’s mostly plastic, poly tape is much lighter than wire. The posts don’t need to be as strong to support it, and it can be stretched tight by hand. Poly tape is also highly visible, which increases the effectiveness of the fence.
H-braces are not usually needed for semi-permanent fencing. It is still a good idea to use heavier posts for corners, however. Corners for semi-permanent fencing should use at least one inch fiberglass. Line posts should be ½ or ¾ inch fiberglass. Posts for semi-permanent fence can be driven into the ground.
Push posts into the ground every 30-50 feet and clip the poly tape to the posts. Poly tape fence can be stretched tight by hand.
Temporary Electric Fence
Temporary fencing uses plastic or small fiberglass posts and poly twine. Poly twine is made of the same material as poly tape, but it is much thinner, only about 1/8 of an inch thick. The twine for temporary fences is usually stored on a reel. The twine can be played out to set up a fence, then reeled in to take down the fence.
Temporary fences aren’t strong at all, but they are quick to set up and take down. Some ranchers move temporary fences daily to keep stock on fresh grass.
Setting Up Gates
Gates are simple to make in an electric fence. The gate handle has a loop or hole on one end to connect to the wire and a hook on the other to hold the gate up. Gate handles that use an insulated metal hook allow the gate wire to be turned off when the gate is down by breaking contact with the wire carrying current.
Solid plastic gate handles are cheaper, but the wire is live at all times, even when it’s on the ground. This shorts out the whole system when the gate is open. If you are forgetful and leave the gate open, it can lead to escapes not just at the gate but anywhere along the fence.
Electric Net Fencing
Electric netting kits are also available. These kits include a roll of electric net wire along with posts spaced to support the net. Net kits are available with the height and net spacing specific to most farm species. These are a little more expensive to purchase, but they are easy to install and move.
Electric nets are a good choice for temporary or semi-permanent fencing for a novice. All the required posts and wires are included with the net kit. The posts usually have a spike on the bottom end to be pushed into the ground.
All you have to do is roll it out, poke the posts into the ground, and connect it to an energizer. Net kits are also simple to move because everything moves as a unit. Just pull the posts out of the ground, fold the net up, and away you go.
Energizers – Making the Fence Hot
Energizers are the piece that makes the fence work. They take electricity from a solar panel, battery, or wall outlet and convert it into the correct voltage for a livestock fence. Most energizers put out 5,000 to 10,000 volts….a huge amount of energy!
Electric fence energizers may have three different power sources. Some energizers plug into wall outlets. Some have solar panels that provide the electricity. Some are battery powered. There are advantages and disadvantages to each type.
Plug-in energizers are the least expensive per amount of energy output. The most powerful energizers on the market are plug-in models. These energizers can electrify the longest runs of fence without losing voltage.
Plug-in energizers work well for permanent fences. They can be installed and attached to the fence, then left alone. They aren’t as good for semi-permanent or temporary fence. These energizers are not portable, and don’t work that well off the grid. Plug-in energizers are best for very long fences and for homesteads with plenty of electric power.
Plug-in energizers need to be in a building near an electric outlet and near the fence as well. You may have to drill a small hole in a wall to either run the power cord in to the outlet or the wires out to the fence. If you run wires out, make sure the wire is insulated so it doesn’t short out against metal building walls.
Solar energizers work anywhere there is sun and are easy to move around. They are more expensive for a given power level than a plug-in energizer. They also may lose power during extended periods of overcast weather or very short winter days.
Solar energizers are a good choice for off-grid homesteads and as energizers for temporary fence. This kind of energizer can be moved right along with the rest of the temporary fence.
Solar energizers are usually mounted on a post that is either part of or next to the fence. Many solar energizers have an opening in the bottom to slide over a fence post to mount the energizer. Others are built to sit on the ground next to the fence.
Battery powered energizers tend to be the smallest units. They are inexpensive and portable, but won’t energize very much fence. They also require batteries, and the batteries have to be recharged in some way. Battery energizers are best for very short fences. These energizers usually sit on the ground next to the fence.
Connecting the Energizer
All energizers have two terminals to connect to wire. One is the hot terminal. This terminal is connected to the fence wire that carries the charge.
If the energizer is close to the fence, the connection can be a short piece of the same material the fence is made of. If the wire has to cover some distance, insulated wire is a good choice to prevent short circuits and keep the wire out of the way.
The other terminal is the ground terminal, used to ground the fence. Grounding is an essential part of the system. If there is no grounding, the fence won’t work.
Grounding the Fence
Grounding is often overlooked, but it is just as important as the energizer and wire. Electricity requires a circuit to flow. Circuits are circles—there must be a closed loop from the energizer through the animal and back to the energizer for the fence to work.
The grounding is the connection from the energizer to the ground. When an animal contacts the electrified wire, the current flows through the animal’s feet to the ground and back to the energizer.
Permanent fencing works best with three six-foot ground rods driven into the ground. These rods must be spaced at least six feet apart and connected to each other and to the energizer.
This completes the circuit and causes a shock to the animal. One of the most common causes of fence failure is inadequate grounding.
Semi-permanent and temporary fences also need to be grounded well, usually with a single ground rod. Using additional grounding will boost the power of the temporary fence if needed.
In very dry or cold conditions, the ground won’t carry electric current well. In these situations, use a return wire setup. These setups use two wires to complete the circuit.
One wire is connected to the energizer like a normal fence. The second wire is connected to the ground terminal of the energizer. The animal must touch both wires to complete the circuit.
Commonly Asked Questions
Can I electrify an existing fence?
Most of the time, you can’t. If the fence includes any steel posts, it can’t be electrified. The steel posts carry the current from the hot wire into the ground, shorting it out. Most standard barbed wire fences and chain link fences include wires connected to steel posts, so they can’t be electrified. (And to repeat, never electrify barbed wire for safety’s sake.)
If you need to reinforce an existing fence with electric wire you will need to run a new wire. You can either attach insulators to the existing fence and run the new wire along the insulators, or just run a separate fence inside the existing one. Both methods will reinforce an existing fence by adding a pain barrier to the physical barrier.
Can I add an electric fence wire to an existing brick fence?
If you can find a way to attach insulators to the fence, you can. Make sure not to add the wire too high. If climbers have their feet off the ground when they touch the wire, the circuit won’t be completed and the fence won’t work. Consider using a ground return wire if you want to electrify the top of the fence.
Can I electrify chicken wire?
As long as no part of the chicken wire touches the ground, or a steel post set in the ground, it can be electrified. Existing chicken wire fences usually have ground contact somewhere, so electrifying those fences won’t work.
For predator control, adding a separate hot wire and connecting the chicken wire to the ground wire is probably a better choice. If you want to keep chickens in, consider using an electric net fence made specifically for poultry.
Are electric fences dangerous? Will it kill my dog (or another animal)?
If you use an electric fence energizer, the fences are perfectly safe. Energizers use direct current, which is much less dangerous than the alternating current in household outlets. The energizers also pulse the electricity, so the actual shock lasts just a fraction of a second. The shocks are painful but not harmful.
I can say from personal experience that charges of up to 6,000 volts don’t cause any injuries. I can also say from personal experience that receiving 6,000 volts is really unpleasant and leads to lots of swearing.
What voltage should the fence be?
The minimum current for a fence to be effective is about 2,000 volts. Most energizers put out much more than this. If your fence is carrying less than this, check for shorts. If there are no short circuits, you may need to purchase a bigger energizer.
Are electric fences legal?
I live in rural Texas, where I am required to maintain secure fences to keep my livestock at home. There are no restrictions on using standard electric fences as described in this article.
The laws in other jurisdictions may vary. Some states require electric fencing to carry warning signs, or to be enclosed in other fencing to protect passersby. If you live within a city, electric fencing may be entirely prohibited—make sure to check the rules of the state, county, and city where you live.
You will be liable for any harm your fence does. If you use a modern energizer that is in good condition, the fence won’t cause harm. If your energizer is damaged, or if do something dangerous like hooking your fence up to a wall outlet, you can be sued for any injuries the fence causes.
Aaron Cummins operates a small farm in the Cross Timbers region of Texas. He raises pastured pigs, grass-fed cattle, and vegetables. He cures pork and makes his own sausages. He enjoys hunting, fishing, and raising his three sons.