Barbed wire

Barbed wire is a type of fencing wire constructed with sharp edges or points arranged at intervals along the strand(s). It is used to construct inexpensive fences. A person or animal trying to pass through a barbed-wire fence will suffer discomfort and possibly injury. Barbed-wire fencing requires only fenceposts, wire and fixing devices such as staples. It is simple to construct and quick to erect by a skilled fencer.

Installation of barbed wire

The most important and most time-consuming part of a barbed wire fence is constructing the corner post and the bracing assembly. A barbed wire fence is under tremendous tension, often up to half a ton, and so the corner post's sole function is to resist the tension for all fence spans connected to it. The bracing, in turn, keeps the corner post perfectly vertical and prevents slack from developing in the fence.

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Brace posts are placed in-line about 8 feet from the corner post. A horizontal compression brace connects the top of the two posts, and a diagonal wire connects the top of the brace post to the bottom of the corner post. This diagonal wire prevents the brace post from leaning, which in turn allows the horizontal brace to prevent the corner post from leaning into the brace post. A second set of brace posts (forming a double brace) is used whenever the barbed wire span exceeds 200 feet (60 m).

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When the barbed wire span exceeds 650 ft (200 m), a braced line assembly is added in-line. This has the function of a corner post and brace assembly but handles tension from opposite sides. It uses diagonal brace wire that connects the tops to the bottoms of all adjacent posts.

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Line posts are installed along the span of the fence at intervals of 8 to 50 ft (2.5 m to 15 m). An interval of 16 ft (5 m) is most common. Heavy livestock and crowded pasture demands the smaller spacing. The sole function of a line post is not to take up slack but to keep the barbed wire strands spaced equally and up off the ground.

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Once these posts and bracing have been erected, the wire is wrapped around one corner post, held with simple fence staples, and then reeled out along the span of the fence. It is then wrapped around the opposite corner post, pulled tightly by hand, and nailed with more fence staples. Then it is attached to all of the line posts with fencing staples driven in partially to allow stretching of the barbed wire line.

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It is installed from the top down.

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There are several ways to anchor the wire to a corner post:

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• Hand-knotting. The wire is wrapped around the corner post and knotted by hand.
• Crimp sleeves. The wire is wrapped around the corner post and bound to the incoming wire using metal sleeves.
• Wire vise. The wire is passed through a hole drilled into the corner post and is anchored on the far side.
• Wire wrap. The wire is wrapped around the corner post and wrapped onto a special, gritted helical wire which also wraps around the incoming wire; friction holds it in place.
• Gripple. The wire is wrapped around the corner post and gripped by a vise which also attaches to the incoming wire.

Barbed wire for agriculture use is typically double-strand 12½-gauge, zinc-coated (galvanized) steel and comes in rolls of 1320 ft (402 m) length. Barbed wire is usually placed on the inner (pasture) side of the posts.

Related Topics:
Gauge - Zinc - Galvanized - Steel

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Galvanized wire is classified into three categories; Classes I, II, and III. Class I has the thinnest coating and the shortest life expectancy. A wire with Class I coating will start showing general rusting in 8 to 10 years, while the same wire with Class III coating will show rust in 15 to 20 years. Aluminum-coated wire is occasionally used which yields a longer life expectancy.

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Corner posts are 6 to 8 inches (15 to 20 cm) in diameter, may consist of treated wood or from durable on-site trees such as osage orange, black locust, red cedar, or red mulberry and are anchored in a concrete base 20 inches (50 cm) square and 42 inches (105 cm) deep. Brace posts are a minimum 4 inches (10 cm) in diameter and are anchored in a concrete base 20 inches (50 cm) square and 24 inches (60 cm) deep. Iron posts, if used, are a minimum 2½ inch (64 mm) in diameter. Bracing wire is typically smooth 9-gauge. Line posts are set to a depth of about 30 inches (75 cm).

Related Topics:
Osage orange - Black locust - Red cedar - Mulberry - Gauge

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