Tips for Choosing a Post Size

Choosing the right size PasturePro Post to use on your high tensile electric fence system is really pretty simple, but here are a few comments to help you make the right selection(s):

Number of strands: This depends on your livestock type and if this is an interior cross fence or a boundary perimeter fence. This will vary from a single strand to up to 7 or more stands. The number of strands is actually not all that important but it determines the height of your top wire.

Height of Top Wire: This is the number that will determine the length of post you will need. Firstly, it has been my experience that very few animals will attempt to actually jump an electric fence that has good voltage in the wires. The animal’s first choices usually seem to be to go under it or thru it. I think this is true of cattle, but especially of goats and sheep. High tensile wire has somewhat of a deceptive depth perception associated with it. Animals and people, when approaching a hot wire, tend to bob and cock their heads trying to gain better depth perception. Jumping over it tends to be a last or most undesirable choice. Although, I have seen top wires at 54-60″ off the ground, I personally do not see a need for it being that high. 48″ off the ground on a perimeter fence is normally quite adequate and 42-44″ would be normal in my mind.

Post Penetration into the Ground: My thoughts are that a 48” post should be a minimum of 12” in the ground and a 72” post should be a minimum of 18” in the ground. Everything in between can be proportionate. But, after having said that, you should also consider the soil conditions on your own particular pasture. A long term period of being is sod, will likely be tighter than a sandy soil that has been row cropped in the past. And, clay soils that you build fence on in damp weather may want to shrink away from your posts when it gets dry, thus requiring more ground penetration. You know your soils better than we do, so always add to the above recommendations when you see need to.

Height of Top Wire plus Ground Penetration: Again, real simple math here; just add these two factors together. For example, if your top wire is 44” off the ground, and your driving the post 16” in the ground, you get 60”. I would suggest that you add a couple inches to that. Using a 66” post here would be suggested. A 72” post would accommodate a 48” top wire height with 20” or more of ground penetration.

Distance of Top Wire from Top of Post: Although you can drill a hole within an inch of the top of a PasturePro post to attach the cotter pin – I would suggest that you allow yourself a few more inches. Additionally, I have seen people install their top wire 8” below the top of the post, just in case they ever wanted to add another wire on top.

Cost Share Specifications for your Area: Whether you are going to participate in a cost share program on your fence or not, it would be a good idea to visit with your local NRCS or Soil & Water District and get a copy of the specifications for line posts for high tensile electric fencing. Each state will have their own specifications, and it would be advisable to read them. For example, I know that the state of Illinois requires a 24” ground penetration for line posts and a determined top wire height that requires 7′ posts (we do not stock a 7′ post but they can be custom ordered).
Post Diameters: Your choice of diameters will be based on your needs and budget. The larger 1-1/2” diameter post will be a little more rigid. It might be a consideration to use a few of these in areas that get a lot of abuse, heavy wildlife crossings or where very deep snow drifting occurs, etc.

One more note. When building fence over ridges and through dips, there is some common sense involved here. The PasturePro Post is a wonderful line post for high tensile electric fences. Part of what we love about them is the flexibility and low maintenance that they offer. However when building over ridges, if they are not perfectly in true line; the posts at the top of the hill may bend in the direction of the true line. This is a good place to use a wood post for rigidity – just in case your fence line isn’t quite as straight and true as you thought it was before you tension the wires. The same thing goes for the dips and low places. These in-line wood posts are called “line bosses” and they add good structure to your fence. In fact, a combination of line bosses and composite posts makes for a great and long lasting fence. This will provide for added rigidity where you need it and flexibility when you need it.


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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