Whether you’re an experienced hand or just learning the basics of wood, wire and tape, there's always something more to learn when it comes to livestock fencing. Jim Gerrish, of American GrazingLands Services LLC, in May, Idaho, and Kevin Derynck, Gallagher territory manager based in Keystone, S.D., shared their thoughts on the seven most common fencing mistakes.
1. Corner posts
This ranks as the top mistake in fencing, be it barbed, high-tensile or woven wire. The main issues are undersized posts and corner posts not set deeply enough, particularly in sandy or soft soils. Gerrish, who has clients in 43 states, says, “the depth in the ground should be equal to, or greater than, the height of the top wire.”
Post diameter depends on the strength of the fence. Gerrish says the lightest-duty fence, such as a 1- or 2-wire, high-tensile pasture subdivision fence, only requires a 4- to 5-inch-diameter post. A 5-strand barbed wire fence, or 5- or 6-strand high-tensile fence, requires a 6- to 7-inch-diameter post. For net wire fences, Gerrish recommends an 8-inch-diameter post.
Keeping corner posts in the ground is Derynck’s chief concern. He says a 10-foot brace is the ultimate, and he favors a “floating diagonal” bracing system, in which the angle brace is a 4-inch by 10-foot post notched a half-inch into the main corner post. The other end is set on top of the ground opposite the corner post.
And he cautions against using drill stem – the metal pipe byproduct of oil wells – for corner bracing an electric fence. Unlike wood, it can conduct electricity and lessen the efficiency of the fence.
2. Post spacing
Fencers tend to use too many posts, which likely stems from people's experience with barbed wire, where the rule of thumb was 1 post every rod length (16.5 feet). In an electric-fencing system, Derynck spaces posts 80-100 feet apart, or about 50 posts per mile.
He suggests using a “stay” – a shorter post that sits on top of the ground and holds wires up – if posts are spaced 100 ft. apart. Gerrish prefers his posts closer together, at 50-70 feet.
3. Correctly sized energizer
Gerrish recommends 1 joule of output per mile of fence, regardless of how many strands of wire. If there’s a total of six miles of fence, it requires a minimum of a 6-joule energizer.
Derynck, who represents Gallagher in Nebraska and the Dakotas, recommends a low-impedance energizer, with a low-amp fuse. “The larger the energizer, the smaller the voltage,” he says, because larger energizers are apt to power through more vegetation and short out. He considers 7,000-8,000 volts high for an energizer.
Grounding is 99% of the electric fence, the specialists explain. Gerrish uses this rule of thumb: 3 feet of ground rods per joule of energizer output. So if the fence is using a 6-joule energizer, 18 feet of ground rods are called for. “Typically this would be three, 6-foot ground rods, spaced at least 10 feet apart,” Gerrish explains.
Gerrish says spacing is key, as a ground rod is essentially an antenna receiving electrons flowing through the soil and back to the energizer, completing the circuit. Ground rods can also interact with a given volume of soil. If three ground rods are driven into the ground 6 inches apart, in essence, they act as one ground rod because of the volume of soil they interact with.
Derynck says most people insert three ground rods near the energizer. He encourages people to space ground rods throughout the whole network of fencing, particularly if the average rainfall of the fenced area is less than ideal for proper grounding.
Galvanized rod is the best for ground rod, and most fencing companies use an insulated galvanized lead-out wire on energizers. “Galvanized isn’t as expensive as copper and you don’t ever have to worry about corrosion,” Derynck says. If there's galvanized wire in the electric fence system, keep everything galvanized. Derynck strictly recommends 12.5-gauge galvanized wire, galvanized ground rods and galvanized connections.
“The most effective place for the ground system is in continuously damp, high-mineral soil,” he adds.
5. Wildlife friendly
Rather than strive for a fence that’s elk and moose-proof, Gerrish suggests a flexible fence. When he moved to Idaho from Missouri, the fencing was high-tensile electric on T-posts, but the T-posts were being bent and insulators broken off due to wildlife. He replaced T-posts with PowerFlex fence posts and has had few problems since, he says.
Another consideration is building a low-profile fence. On Gerrish's 2-wire range fences, the top wire is at 30 inches and the second wire is at 20 inches. It’s designed to allow antelope to go under the wires at a dead run, but low enough that elk will hit the fence with their legs and not the heaviest part of their body.
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6. Gate openings
In an electric-fencing system, creating a gate system that conducts current is a challenge. Derynck recommends placing a floating diagonal brace on either side of the gate opening.
To keep the fence “hot,” trench both insulated hot and cold galvanized wires 1- foot deep under the opening (perhaps deeper in high-traffic areas or low-lying wet spots, or shallower in less-used pasture settings). “The gate no longer needs to carry current, because you have your current going underneath the ground,” he says.
“Putting a steel post anywhere into an electric fence is a big mistake, because you are then relying on the insulator to keep your fence from shorting out,” Gerrish says. He prefers highly flexible plastic or wood-plastic composite posts, “No matter how good an insulator you get, eventually something's going to break or pop off, and you have the potential for dead-shorting.”
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