Want to hear a Captain Obvious statement? Electric fences need to be able to shock animals enough to keep livestock in and predators out.
The reality is many electric fences are not up to this basic task.
Just ask Jason Williams, who tours the country teaching producers ways to make their electric fences more effective.
It’s not that producers are ignorant of the basics, he says, it’s just electric fencing can be a more precise science than many imagine.
Here are some of his top dos and don’ts:
Do: Invest in quality materials
There’s no industry body which enforces minimum energizer, wire, and grounding standards for electric fences, but Williams has several suggestions on this score.
One of the biggest things to look out for is unrealistic distance claims for fence energizers (commonly called ‘fencers’), said Williams, Canadian regional manager of Datamars, a company which offers livestock management solutions.
“People will look at a distance claim and think that with one crappy piece of barbed wire they can run their fence 220 miles from Saskatoon to Regina,” he said.
If a distance claim seems too good to be true compared to the price, it probably is.
“People are led to believe they can do massive fencing projects with a $100 unit, and they go and have a wreck. It costs the same amount in labour and time to install high-end products that will last 20 years or more as ones that will last four years. Maybe one is twice as expensive but you get five times the life.”
Wire choice is also key.
“If you’re planning to build a permanent construction — a fence that is going to stay built and in place for 20 or 25 years — you should use 12-1/2-gauge high-tensile wire,” he said.
“Seventeen-gauge wire is available but it’s tiny and hard to push power through. The 12-1/2 gauge is considerably thicker and carries power easier.”
Don’t: Skimp on wire
Producers often tell Williams they’re not getting extra voltage on their fence despite buying an energizer that is two or three times more powerful than their old one. He explains this by comparing energizers and wires to a water pump and a garden hose.
“If you bought the largest water pump on Earth and tried to push water through a garden hose, it wouldn’t be much more effective than using a little half-horsepower common pump,” he said. “You can move more water by using a bigger hose.”
It’s the same for energizers and wire.
“More strands on the fence create an easier flow for electricity. Without enough flow even the largest energizer simply cannot release its potential power. You either have to use more strands of wire or use wire with better components — such as aluminum and copper — which allow more power to flow,” said Williams.
“Single wire is probably not the best choice for a permanent fence structure. But if you want to break up your pasture into small grazing paddocks that are only going to be there for three or four days each, by all means use single wire.”
Some situations demand what may seem like overkill.
“To build a good fence I would say you need at least two strands. If I need to carry power for miles and miles, I might leave a yard with six wires. That knocks some people’s hair back because they think six wires must make it six times harder to put power to the fence, but it’s actually six times easier. The more strands of wire we have that are all connected to each other, the easier it is to move power.”
Williams often sees producers using rebar as grounding instead of more optimal galvanized ground rods.
“Rebar cannot be used as a ground bar because the outer edge of the rebar product is rust, which is actually an insulator,” he said. “If you have a chunk of rusted steel in the ground it does nothing to encourage the shock to the animal. You need to use a galvanized ground rod.”
Another common error is using supposedly rubber hoses or inner tubes as insulators at the corners or ends of a fence.
“Pure rubber is an insulator, but we do not have any products in Canada that are pure rubber. A garden hose is probably closer to pure carbon than pure rubber and carbon is very, very conductive. They are defeating the purpose.”
Williams often sees producers place ground rods at their barn sites. Although that may seem like a good idea in theory, ground rods should actually be installed at least 60 feet away from a shop or barn.
“They can place the energizer anywhere but cannot use a ground rod from a barn or shop. Otherwise you allow leakage of voltage into the barn or shop instead of keeping it on the fence.”
Do: Design for the worst scenario
Moisture in the soil is perhaps the ideal conductor, helping the soil transfer the shock back to the ground system. Typically, the better your soil moisture, the more conductive your electric fence will be.
Trouble comes, however, when producers build fences based on ideal soil conditions. In other words, if you’re in the Olds area — which often has jet-black, fertile, and conductive soil in late April — you want to pretend you’re building a structure in a far drier southeastern region like Medicine Hat.
“Build most fences as if you have poor soil,” said Williams.
This is where the “one ground rod for every two joules of output power” rule of thumb comes in handy. Producers in areas with moist, conductive soil may be able to get away with fewer rods in April and May, but they shouldn’t try, he said.
“The trouble with Western Canada is by August we are often in a drought, which means less conductivity. The setup that works in April and May may not work in August.
“I want producers to err on the side of August and build a structure for that time instead of April. We overdo it now to save our bacon later.”
So how do you know if you have enough ground rods? Williams suggests the following test: The first two steps are to turn off the energizer and then heavily short circuit the fence — at least 330 feet away. Then turn the energizer back on and in step four, check the fence voltage with a digital volt meter (fence voltage should be two kilovolts or less) beyond the short circuit. Finally, in step five, check the ground system (probe in ground, clip on the last ground rod).
“If you get to step five and have more then 300 volts in your sensor you need to add more ground rods until that number is below 300 volts or 0.3 kilovolts,” said Williams. “The voltage you decreased on the ground rods will appear back on the fence.”
Do: Train animals early
Livestock need to learn to fear the fence or it won’t be a deterrent, said Williams. Spring is an ideal time to train animals with a short, sharp shock.
“The ground is usually moist in spring and moisture tends to invigorate how much shock can be transferred,” he said.
“The painful shock they feel this time of year can help producers for the rest of the season. Typically it only takes one or two brushes up against the fence to make them realize, ‘That area of the pasture hurt me — I’m not going to stick my head there.’”
The alternative is animals that do not respect the fence, causing them to possibly escape their confines.
“If you graze animals in barbed wire all summer long and then you try to run a single hot wire to divide up pasture, they’re not going to respect it because they scratched and pushed and messed around with barbed wire all year with no ill effects.”
Ideally, an animal should touch two wires when contacting the fence. This causes them to be shocked in front of their ears (if it’s shocked behind the ears chances are it will move forward and not back up). This means spacing the wires to the facial dimensions of the animal you’re trying to keep in or keep out.
“The spacing of those wires can be no larger than the distance between their nose and eyes,” said Williams. “For cattle that means 10 to 12 inches, 14 inches for horses, and down to four inches for predators.”