As you begin planning for new or upgraded electric fencing this spring, be sure to remember the importance of lightning protection as well as proper wire selection.
Undoubtedly, living in the Ozarks means you’re going to have to contend with the weather at one time or another. A thunderstorm poses special concerns for those with electric fencing. Bottom line, you want to do all you can to protect your livestock – and your fence – from deadly lightning.
Lightning Protection
All energizer installations should have adequate lightning protection installed before the fence is constructed.
1 Use a good surge protector on the utility power side of the energizer to protect against power fluctuations. Most energizers are damaged from the power side, not the fence side.
2 Install a lightning choke or coil in the leadout cable. This can be home built or commercial.
3 On the fence side, connected to the powered fence, install a lightning arrestor, home built or purchased, then connect to the lightning grounding system.
4 The lightning protection grounding system should be installed at least 65 feet from the energizer grounding system. This needs to be a more efficient system than that for the energizer, therefore, use at least one more rod. Select this site with care. You don’t want a lightning strike going to ground in the middle of a herd of cattle.
5 It’s also helpful on a lengthy fence to install a ground rod and arrestor at any known permanent wet spots along the fence. This could enable a lightning strike to go to ground without traveling back up to the energizer installation.
6 On multi-wire fences, be sure to connect the top wire to the lightning arrestor. The top wire is your first line of defense against lightning damage.
Wire Selection
Few, if any, permanent and semi-permanent fences should be constructed with anything other than 12 1/2 gauge high-tensile wire with type III galvanizing. (A caution is to avoid the 200,000-PSI or more rated wire if possible, as it’s very stiff and hard to handle.) The smaller gauge wire has a high resistance to the movement of current and on a longer run might necessitate the use of a larger, more expensive energizer. Graph 1.1 illustrates this point:
Or, in other words, 16 gauge is 2.5 times as resistant to current movement as 12-1/2 gauge. Another point to consider – aluminum is four to six times as efficient as steel wire, but solid aluminum wire is soft and easily broken. Aluminum coated steel wire is available. A note of interest – aluminum is only 60 percent as efficient as copper, but the price of copper or copper-coated wire would be prohibitive.
Another point to consider is to never electrify barbwire. The barbs greatly increase the resistance of the wire; the wire is not galvanized adequately to prevent rust as long as high-tensile. Also, it is more costly, and there is always the chance of becoming entangled in the wire. SAFETY IS OF THE UTMOST IMPORTANCE.
Temporary Fencing
Polywire is a very useful product that most landowners can utilize for paddock divisions, strip grazing, etc. But, the fine metal conductors in polywire and the polytape type of products create a very high resistance to current flow; therefore, it should not be depended on for long runs. Six and nine strand polywire with stainless steel conductors should be used. Six-strand polywire has a resistance of 9,700 OHMS per mile and three strand has a resistance of 16,000 OHMS per mile.
