Lightning Strikes and Fence Wire

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Photo courtesy of freedigitalphotos.net

It is not a matter of if, but when your wire fence will get struck with an uninvited bolt of lightning.  A wire fence is a large antenna that can act as a highway for lightning to travel to ground.  As a lightning strike travels down the wire looking for an exit, it may destroy fence posts or energizers, harm animals or humans, and could even cause a fire.  Fences should be constructed to safely withstand a strike. There are multiple ways to protect against damaging strikes.

Possibly the easiest way to protect your fence is with a lightning arrestor.  A lightning arrestor is a straightforward porcelain apparatus. An arrestor is connected by running a wire from the hot line of the fence to one terminal of the arrestor, and attaching another wire between the second terminal and an independent ground rod.  The two terminals are kept at a specific distance apart so electricity will bridge the gap at above higher than normal voltages (lightning strike).  When lightning strikes the fence, the electricity will arc across the gap in the direction of the ground rod.  Mild hits do not normally hurt the arrestor.  If you hear a clicking noise in the arrestor when the fence is running, it more than likely needs to be replaced. Although a porcelain arrestor does not offer superior protection, they are easily installed and replaced for little cost.

MWLAGraphicOnly_WEBAnother handy protector is a lightning diverter, or induction coil.  The lightning diverter works to slow down or diverts the reverse flow of electricity on a fence wire. The choke coil is designed to slow the surge of electrical energy by inductive forces created in the coil from the energizer.  When lightning strikes, the pool of energy searching for ground jumps the gap of the diverter and finds the shortest and fastest path to ground.  The lightning diverter is a wire coil that creates an electromagnetic field when electricity flows through it.  When the energizer is forcing out electricity, an electromagnetic field is set up around the coil.  If electricity tries to come backward on the fence (lightning strike), not only does it have to resist the flow of electricity from the energizer, it also has to reverse the electromagnetic field around the coil. Granted this type of protection is more labor intensive because it needs a separate ground bed at least 50’ from that of the energizer, it does not need to be replaced after a strike.  Slowing down the strike and diverting it to ground quickly will save a devastating blow to your energizer.

It is also a good idea to place ground rods along the fence during or after construction to protect not only your energizer, but also humans and livestock.  It has been noted that lightning can travel at least 2 miles down a fence line.  So lightning could strike the fence two miles away and cattle could be standing tight to the fence line, or a ranch hand could be shutting a gate and get electrocuted.  Create a safeguard by installing ground rods near fence posts every 150’ along the fence line about 5’ deep.  Remember electricity is always looking for ground.

Safety First

Farm safety is so important and not spoken of often enough.  Protect your energizer by installing lightning protection, not matter what type.  Some protection is better than none. Keep in mind we cannot stop Mother Nature or the results of a lightning strike, we can only be prepared.  Stay safe!

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