Understanding Wire for Farm Fencing

All “agricultural fencing” in the USA, consists of low carbon wire or high tensile wire. Low carbon wire is made from steel rod with an approximate 0.10% carbon content. While, this type of wire is easy to work with, it is prone to elongation (as in, stretching and sagging) and is weaker than high tensile wire. High tensile wire is made with steel rod which has approximately 0.28% carbon content.

The higher carbon content in high tensile wire significantly increases the wire’s strength and reduces elongation (stretching and sagging). Because of these improvements, it is possible to replace low carbon wire fencing with high tensile wire fencing of a smaller diameter.

A 12.5 gauge wire in high tensile would have a breaking load of nearly 1000 pounds (or more, depending on the psi rating), whereas, a 12.5 gauge low carbon wire would have a breaking load of 460 pounds. This would be as in comparing a 12.5 gauge high tensile wire with 12.5 gauge low carbon barbed wire.

High tensile fencing is easier to install because of its lighter weight and requires fewer posts during installation than low carbon fencing. When properly installed, high tensile fences require little maintenance and remain tight for years. Low carbon fences require regular maintenance and will stretch and sag over time.

The finish or coating of the wire will have a bearing on how long it will last. Class 3 Galvanized coating is the standard for most standard high tensile wire products. This coating is approximately 2.5 times thicker than the industry standard Class 1 Galvanized coating. Class I coatings are normally what is found on standard low carbon barbed or woven wires. Class III coatings will last three to four times longer than class I. There are also some new finishes available today such as the Zinc/Aluminum coating. This hybrid coating lasts more than twice as long as Class 1, but normally uses less coating than Class 3.

There is also a new painted finish becoming available; which combines a color polymer paint over a zinc/aluminum coated wire to give you longer fence life in attractive colors.

With high tensile fencing, you can build a longer lasting, lower maintenance fence for nearly half the price of a conventional low carbon fence.

The above article is a generalization, of wire properties, for farm fencing and written in layman terms as only a guideline for farm fencing. If you would like to read more technical information from a manufacturers point of view I would suggest going to http://www.bekaertwire.com/galvanizedwire.html. Bekaert is a wire manufacturer and their site gives a more complete description of the different coating processes that are currently being used worldwide.


About Gary Duncan

Gary has been active in the fence business for over 15 years. He also raises Highland cattle in a management intensive grazing system and was the first person to market the PasturePro post back in 2005. He enjoys discussing all things grazing and is the main contributor to the blog.
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5 Responses to Understanding Wire for Farm Fencing

  1. avatar Ryan says:

    What is your opinion of the Bekaert 14 gauge ZA + paint Cattleman wire? I thought this might be a good selection over the 15.5 gauge high tensile wire.

    • avatar Gary Duncan says:

      Hi Ryan, I assume you are talking barbed wire here. My opinion is that as an electric fence guy I dont think much about barbed wire and do NOT recommend electrifing it. But there may be a time and place for it……
      This is what Bekaert has to say about it: [ Cattleman® Barbed Wire is perfect for your most demanding fence jobs. It's 30% stronger than 12.5 gauge low carbon and 15.5 gauge high tensile. And Cattleman® gives you all the benefits you'd expect from a Bekaert fencing product - easier installation, increased post spacing, less maintenance, and long life.
      Cattleman® is Class 3 (heavy coat) Galvanized. This means it will last two times longer than Class 1 Galvanized fences. You can also choose Cattleman® with ZA + Paint advanced coating. This version of Cattleman® Barbed Wire is available with a green finish and will last four to six times longer than a standard Class 1 Galvanized fence and enhance the appearance of your property as well.]
      ref: http://www.bekaertfence.com/products/cattleman14.html
      I have seen some of the HT Zinc /Alum +green painted barbed wire installed and it was actually about as pretty as barbed wire can be. The finish and coatings on this wire are “state of the art” and will last a long time as they say above; 4 to 6 times longer than standard barbed wire. I believe that product is made in the USA and thats a plus. And this manufacturer is known for superior technology, quality and consistancy.
      Whats your purpose and application for using it?

  2. avatar Craig A. Olson says:

    Gary, thank you for this article. I will be installing a half mile of 5-wire fence this spring through somewhat rocky, hilly woods for cattle. It must accomodate trees falling on it over time. Most new barbed wire fences are trashed within a year or two in these conditions, so I am considering high-tensile with plastic insulators as sacrificial (breakaway) hangers. I plan on electrifying it so I can keep the tension under 200lb. My concern is the tension springs may not give enough when a tree falls, so I’d like to install a “fuse” into each wire in the center of each fence section. Will splicing in a 1-foot piece of soft 12.5 gauge aluminum wire into each wire work for this?

  3. avatar alfred mills says:

    I am replacing old class 1 fence. what is the down side between class 3 vs zinc aluminum fence I need about 5000 ft

    • avatar Lacy Weimer says:

      Class 3 and Zinc Aluminum are both great wire coatings.
      Zinc Aluminum will resist rust longer than Class 3, especially in moist climates.
      Zinc Aluminum is often used in areas that get a lot of salt residue, such as near highways or the ocean shore.
      Class 3 will resist rust in a normal climate up to 40 years.

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