To anyone who’s never built one, an electric fence can seem like a pretty simple structure.
In some ways they’re right — like any kind of electrical circuit, an electric fence requires a source of power, a conduit, some kind of ground and usually insulators.
But, as is often the case, it’s only as good as its weakest link.
An effective fence starts with what you put in your shopping cart, said Greg Paranich, a self-described electric fence “troubleshooter.” Some producers cheap out on components or make tiny compromises to their detriment, he said, adding he’s as guilty as anyone on this score.
Paranich did everything “to the nines” when he built his first electric fence more than three decades ago.
“But something in my head said ‘I’ve spent enough money,’” he recalled. “Instead of buying the recommended galvanized ground rods I used lengths of rebar steel every farmer has by the shed or the barn — they were handy and cheap and I had them.”
Now he knows better.
“When I upgraded my grounding system to where it was supposed to be, I noticed a dramatic improvement in how much more consistent my entire power system would operate.”
If you’ve never built an electric fence before, “start small, start basic, but start,” said Paranich, an agricultural field specialist with the Grey Wooded Forage Association.
“I always encourage people to look at their long-term picture and break it down to their basic core design,” he said. “It’s like you’re building an electrical transmission system across your farm or ranch.
“Start with the basic conduit of how your power is going to get out. Sometimes it might just start by putting in the one transmission line that would bisect the pasture. From there you can tap off of it just like you would tap off the power line that goes past your property.”
Choosing the power of the energizer (the units that electrify the fence, also called the ‘fencer’) depends on a number of factors, particularly fence length. You may want to talk to a vendor or other expert before making your choice, but in Paranich’s experience it’s best to choose an energizer that’s more powerful than what you need in the short term.
“I always err on the side of having more (power) than you need because when you expand the fence, you’re always going to be within the capability of that energizer. That’s really important. I’ve seen systems that were built very well structurally but they didn’t have enough power generation. It’s like having a great truck but putting a tiny engine in it — it’s not going to perform to how it’s designed.”
As far as other considerations go, well, that depends.
“The answer to 95 per cent of ag questions begin with the phrase ‘it depends,’” said Paranich.
“It’ll depend a lot on what your circumstances are from one field to the other, what they are from one ranch to another, what your resources are, and what your vision is and what you want from it.
“Those are the type of discussions we have when we build anything — whether it’s a fence or a barn or any kind of structure.”
The process of briefly shocking an animal is essentially the creation of a circuit. The fencer provides an electric current through the wire, the animal receives the shock and the electricity is returned to the earth via some kind of ground. In the case of electric fences, that usually means a ground device buried deep into the earth.
In order to work effectively, a ground device has to be conductive. Water itself is highly conductive, and that’s why moist soil can be an ideal conductor. However, dry or frozen ground can cause a system to work below expectations and so galvanized steel ground rods buried six to nine feet (with a few inches showing) are used.
While emphasizing he’s not an electrician, Paranich said the main reason galvanized steel is the best choice is because it doesn’t corrode.
“If you have different types of metal like aluminium or steel they will have an ionization in between them which can cause corrosion and minimize the amount of direct contact. At different points you’ll be losing some of that energy,” he said.
So why do the rods have to be buried so deep?
“You want to have them going down deep enough so you’re ensuring that ground contact with any current travelling through the ground,” he said.
High-tensile wire recommended
Producers can sometimes be reluctant to make the leap from barbed to high-tensile wire. Although barbed or twisted wire can be used, it’s usually not considered optimal.
“With twisted wire both wires will be energized, but there are gaps between them that can cause shorting,” said Paranich. “Anytime you have an air gap between the connection you can get some bleeding of power.”
The standard for a permanent electric fence is 12.5-gauge high-tensile wire. Thinner gauges are typically not appropriate as it’s like connecting a garden hose to a powerful water pump, he said.
“When you’re pushing that power out of your energizer and it doesn’t have the proper gauge of wire going out, then you’re restricting the capability of how much energy it can actually carry,” he said.
There can be a bit of a learning curve with high tensile wire and consider consulting an expert the first go-around, said Paranich, who recommends not setting this wire inflexibly stiff like many barbed-wire fences. Wires can expand or contract depending on the weather and you want about the same baseline tension in either case.
“In the fall before winter l might go around and loosen up the tension of the wire on my fences slightly,” he said.
Although they come in many forms, insulators are typically plastic or ceramic devices attached to fence posts and are intended to prevent shorts between the electrified wire and the post. Paranich highly recommends them.
“There are people in Alberta saying ‘We don’t use them — we just up the power.’ That could work but you will get some shorting out.”
Insulators must be made from high-quality material, he added.
“I find that over time — and that might only be two seasons — that cold and UV rays start to break down the plastic and they get brittle and break. Whereas if I buy lots of good-quality insulators, they’ll last for years and years.”