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The Shocking Truth About Electric Fences Part 1

By John Kirchhoff


People have mixed feelings about the use of electric fences. For people unfamiliar with them, the word “electric fence” conjures up images of a well-done corpse hanging off a prison fence. Those folks usually consider them an instrument of animal torture at best.

Some users will say they’re ineffective and useless while others consider them the best thing to come along since sliced bread. One person told me his fence was inexpensive to build and very dependable and the next says hers was very expensive and undependable, with the accent on “was” because she’s no longer using one.

I’ve had situations where fences were ineffective, yet no one knows better than I the unique, effective and memorable pain delivered by a powerfully charged fence. For the record, a well constructed and maintained electric fence will deliver a painful, but not life-threatening shock that is effective for not only keeping domesticated animals inside, but predators outside of a designated area.

Electric fences are one of the most effective methods of deterring four legged predators because they do the job by using psychology rather than having to present an impenetrable, physical barrier.

A coyote eyeballing your tasty new lambs has no fear of a conventional fence and will keep testing the fence until a weakness is found. If he can’t jump over, climb through or go around the fence, he’ll dig under and soon be enjoying his feast. If you plug that hole, he simply digs a new hole a few feet away.

When a coyote tries to climb through or dig under a “hot wire,” he gets an electrical jolt that knocks him back on his heels. Most only need one shock, after which they give a wide berth to any fence that looks like the one that zapped them.

Types & Components Of Electric Fences

Electric fences mostly fall into two groups: “Permanent”—lasting for 20 or more years and requiring little maintenance—and “temporary”—a fence that may be erected for a few days or months for the sole purpose of grazing a particular area.

The most important thing to remember is that rather than physically containing the animal, an electric fence uses the fear of pain to contain or exclude the animal.

To establish and enforce this fear, four components are necessary and a weakness in any one will reduce the effectiveness of the fence as a whole, much like the way one flat tire totally disables your car. The four components are the energizer, conductor (wire), post and insulator and ground circuit.

The energizer turns low voltage household current, battery power or sunlight into a high voltage, teeth-jarring electric shock.

The conductor transmits this shock to the unlucky soul that touches it. The conductor is usually galvanized or aluminum-coated steel wire for permanent installations and for temporary installations, plastic “poly” wire, tape, cord, rope or woven (net) is often used. Made in a number of configurations, all poly wires have tiny copper or stainless steel wires woven into the synthetic fabric, which enables it to conduct electricity.

The post-insulator combination supports the conductor at the desired height and prevents the electricity in the wire from leaking into the ground through the post. Some posts are non-conductive and therefore self-insulating while others require a separate insulator attached to the post.

The ground circuit is extremely important but oftentimes is the one thing we have little control over. It’s important because it enables the electricity contained in the wire to return to the energizer, thus providing a shock. The absence of a ground circuit is why a bird can sit on a 6,600 volt power line and not go up in a puff of smoke.

The ground circuit most commonly uses metal rods driven into the soil near the energizer and are connected to it by a wire. When something or someone touches the conductor wire, electricity flows from the wire, through their body and into the soil where soil moisture carries the electricity to the ground rods and finally back into the energizer, completing the circuit. To produce a shock, electricity leaving the energizer terminal labeled “fence” must return to the “ground” terminal. To build a fence that works, you need to understand, mesh together and apply the four components.

Controlling Sheep With Electricity

Compared to other species of domesticated livestock, sheep are the most difficult to control with an electric fence. Horse, cattle and even goat producers don’t realize how easy they have it when it comes to building an effective electric fence.

A horse can get zapped by less than 2,000 volts and will almost never try the fence again, whether it’s turned on or not. 2,500 volts will easily turn a cow but you better have a good 4,500 volts to even get a sheep’s attention.

For much of the year, wool sheep have a thick coat of wool that helps insulate the animal from shocks and the heavier coat that hair sheep wear in cold weather and early spring is equally effective.

In addition, if one sheep makes it through the fence, herd mentality demands everyone else follow, whether they get shocked or not. Think of lemmings throwing themselves off a cliff and you’ve got the idea.

Compounding the problem is when sheep go under the wire, the hair or wool winds itself around the wire and creates a very effective insulator, which lessens the chance of anybody following getting zapped.

Worst of all, it seems both sheep and goats will try the fence daily to see if it’s operating. I know cow people that leave their fence turned off for weeks at a time but if my energizer fails today, I can rest assured knowing sheep will be out tomorrow.

Advice From Non-Experts

For the sheep producer, going to the local farm store or co-op for advice on building sheep tight electric fence is an exercise in futility. Not knowing I design grazing systems for a living, it’s often entertaining to hear them tell of how well their product works, how effective it is at controlling stock and so on.

Most of what they say is true, however to them “stock” is cattle and horses and the difference between an effective cow or horse fence and an effective sheep fence is as different as night and day. The former can usually be controlled with a single wire powered by a rather low output energizer while sheep fence requires anywhere from two to six wires powered by a powerful energizer.

Will An Electric Fence Work For Me?

Before you even look at a fencing catalog, you need to decide if an electric fence is right for you and your operation.

Everything in life has tradeoffs and fences are no different. Compared to a conventional woven or barbed wire fence, electric fences require less labor and expense to build initially but do require periodic inspection to maintain their effectiveness. Materials for an adequate 4-wire electric sheep fence will cost around half that of a woven wire fence. Time demands for installation are also considerably less.

I don’t recommend using electric fences on property lines, especially along busy roads. A storm during the night can knock out the electricity for a few hours and you won’t know the sheep are out until a highway patrolman interrupts your breakfast asking if it was your sheep that caused the car accident.

A woven wire fence is hard to beat when it comes to preventing that kind of liability.

If predators are a problem and dig under your woven wire, adding an electrified wire near the ground (preferably on the outside) is very effective.

If you have an existing conventional fence that’s in bad shape, adding two electrified wires approximately 6 and 18 inches above the ground on the inside is quicker, effective and much less expensive than tearing out and rebuilding the old fence. Insulators are made that will hold the hot wire 6-12 inches away from the old fence and will prevent short circuits caused by the energized wire touching the old fence.

For multi paddock grazing systems or subdividing pastures, electric fence is an excellent way to go. My rotational grazing system has 24 paddocks with woven wire perimeter fence and electric interior fence. If the sheep get through the interior fences, it’s frustrating but not the end of the world because they’re still in the pasture and not on the road.

If you decide an electric fence will fit your operation, you need to give thought to the different components mentioned earlier that will comprise your fence. There’s a world of products out there of which some will meet your needs while others will over or under serve them. It’s the over and unders that can hit your pocketbook hard.

Energizers: Heart of All Hot Fences

“How big of an energizer should I buy?” My grazing clients ask me that question quite often and my standard reply is, “Bigger than you think you need.”

When asked how much money they should spend I tell them, “More than you think you should.”

The problem is that sometimes an energizer that is powerful enough at present isn’t powerful enough long term. Most people at some time in their grazing career (myself included) have bought an energizer that seemed expensive enough or powerful enough at the time, but made the mistake of not considering the possibility of future expansion.

I’ve found energizers are a lot like shoes, price doesn’t always equate to performance and we tend to outgrow them in a few years.

Years ago when I had just a few sheep, my “little blue jewel,” a $175 (the current price) name brand New Zealand energizer worked great. As the flock grew and additional fence was added, the sheep started getting out.

I figured I didn’t have enough wire strands to hold them, so I added more wire and lo and behold, even more sheep were getting out!

That didn’t make sense!

After chasing sheep for a week, I finally realized my fence had outgrown my energizer. Even though the “little energizer that could” had the heart of a warrior, I’d added so much fence that the little warrior could no longer support the load and the sheep discovered this before I did.

My response to sheep getting out had been to add more wire, which only made a bad situation worse. The overload of wire pulled the voltage down until the “hot” wire wasn’t much more than lukewarm. I’ll explain that phenomenon later.

Once I realized what I was doing wrong, I bought a $100 (price at the time) red American made energizer that spoke with considerably more authority. At least that’s what I gathered from watching sheep get knocked on their rears. I must admit, that sight most definitely gave me a feeling of satisfaction!

Several years later, history repeated itself after I converted the entire farm to pasture. Hooking up 10,000 feet of multi-wire fence to “Old Red” certainly made him grunt, but when the bottom wire was deep in wet grass, it knocked the wind clear out of him and lambs started getting out. So, back to the energizer store I went.

Well not exactly.

By now the first place pretty well knew me by name and I really hated to show up again with the same tired old story. So I instead went someplace where they didn’t know me as well and bought a black $200 (price back then) American made unit with a funny name that made me think of African wildlife. I installed it one rainy day and after plugging it in, the fence voltage immediately went up an additional 3,000 volts. It sure set those wet lambs back on their heels and that alone gave me $200 worth of satisfaction!





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