Tensioning High Tensile Wire

Part of the beauty of Class III, 12.5 gauge high tensile (HT) smooth wire is its ability to stretch while maintaining a tension memory. By that I mean that it can stretch but will return to its initial tension after it has been stretched. Although different brands in different PSI ratings may vary somewhat, generally a 12.5 gauge HT wire can stretch up to 2%. Now, that doesn’t sound like much, but in a quarter of a mile (1320 feet) that 2% relates to 27 feet. And the amazing part is that once it should get stretched that much, it will return to its initial tension. The breaking point of most 12.5 gauge HT wire ranges from 1100 to 1500 pounds. Again, this will depend on the PSI rating of the wire.

When you install HT wire, you should put from 200 to 250 pounds of pull on it. I personally will usually be on the lesser side of that. When I tension it up I will usually watch the sag between my line posts and when the sag is almost gone I stop tensioning. I do not want it banjo string tight so that I could play an E-Sharp on it. Once tensioned up it should be springy and bouncy, kind of like a rubber band.

I love this springy and bouncy part. I also feel that whatever else we do during the installation process that we should strive to allow the HT wire to remain springy and bouncy. Should the fence be pressured by trees or tree limbs falling on it, ice storms, wildlife running into it or a magnitude of other human related challenges – it can easily handle most things that are thrown at it without breaking or repairs needing to be done, other than removing debris from it.

Here are some comments that will help provide for a great and low maintenance HT electric fence:

  • Do not restrict the fence wire from horizontal travel. Make sure that the wire has free travel through staples, insulators, cotter pins and the like. Allow it to move and/or stretch.
  • Do not use any more line posts than you need. The purpose of the line post is basically to maintain your wire spacings of multi-wire fences and support the wire vertically. I have seen line post spacing’s range from 20 to 100 feet. Do not be afraid of putting line posts from 50 to 75 feet apart. The wire when properly tensioned will handle this distance. The exception here would be fences that go over and down steep hills where you may need tighter spacing’s to keep the wire off the ground and at the desired height off the ground.
  • Avoid using steel posts as line posts or ends. Steel is your enemy with electric fencing and should be avoided unless you want to spend the rest of your life chasing shorts.
  • DO consider using an insulated and flexible line post. One that will also hold itself in the ground.
  • DO use wood posts at corners, ends and any transitional changes. Brace your corners and ends appropriately. Also use wood posts at all vertical terrain changes, such as tops or bottoms of hills.
  • Handle your wire carefully during installation. The class III coating is very tough and will provide for a long life, however if you should get kinks or deep abrasions during installations you will likely have a broken wire at the most inopportune times. If you accidentally kink a wire, it is best to repair it on the spot.

Is there an ideal line post for HT wire? We feel that the PasturePro posts offer all the benefits that you would want in a line post. They themselves are flexible, springy and tough and allow the HT wire to move with any pressure and remain springy and bouncy. They also have an amazing amount of ground holding power. They tend to stay in the ground where some other types of material are slick sided and tend to lift out under upward or sideways pressure. If you have not tried any yet – you owe it to yourself to put some in the ground and decide for yourself. We are pretty liberal with samples – call us and we can put you in touch with a distributor near you or send you some to try. Here’s a video showing how the posts work in coordination with the wire:

Yes, I have had my own cattle run thru my own fences with 10,000 volts running thru them. Usually when they were feeling their oats or I had done something foolish. And, what always amazes me is that I’ve rarely ever had to make any repairs. The wire stretches, the posts bend – and then everything returns upright and good as new.


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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