Lightning, by far the most powerful force on earth, occurs when a thundercloud becomes polarized with a positive electrical charge in the upper regions, and a negative charge in the lower regions. Updrafts carry positively charged ions skyward, while heavier, negatively charged ions are sped earthward on downdrafts. Immense electrical charges – up to 100 million volts – build up rapidly between the opposing poles in the cloud.
At the same time, the earth (usually negatively charged) builds up a positive charge caused by the negatively charged ions in the base of the cloud. Eventually, the charge becomes so great that it overwhelms the atmosphere’s ability to act as an insulator, and in one of Nature’s most spectacular optical illusions, a white-hot (50,000º F) stroke of lightning forms within millionths of a second and surges skyward at the fantastic rate of 422 million feet per second.
The awesome power of lightning is sometimes freakish. It has been known to melt holes in church bells, weld chains into iron bars, and cook potatoes while still in the ground. And contrary to popular belief, lightning does strike twice in the same place: the Empire State Building is struck by lightning about 50 times a year.
Each year, lightning strikes 400 people; killing 20% of its victims and leaving another 70% with serious long-term injuries. According to the Insurance Information Institute, in 1990, national lightning damage amounted to nearly five percent of all paid insurance claims, with residential claims alone exceeding one billion dollars.
Lightning is responsible for more than 80% of all livestock losses due to accidents and some 10,000 forest fires are attributed to lightning in the U.S. each year. Most livestock losses to lightning are not from direct strikes, but result from animals perishing in barn fires or brush fires started by lightning. Occasionally, lightning will strike an animal in the open, but most livestock deaths in the open are the result of animals congregating under a tree or around a pole that is struck by lightning.
Preventive measures
While not all losses to lightning can be prevented, they can at least be mitigated by the installation of lightning protection systems for buildings, trees, fences, windmills, silos, etc. An effective lightning protection system includes many essential parts.
The five key parts of a system are:
- Air terminals (lightning rods): Designed to attract and take any lightning bolt that may strike in the immediate area
- Down (or main) conductors: Conduct the lightning bolt safely from lightning rod to the ground
- Secondary conductors: Connect metal parts of buildings to the main conductors
- Lightning arresters: Protect a building’s wiring system from lightning surges.
- Ground connections or rods: All grounding systems should enter the ground at the same point to prevent dangerous side flashes: telephone, electric service, antennas, metal plumbing including underground pipes and conduit, and lightning protection systems.
Installing lightning protection systems providing at least two grounds for all buildings, being sure to ground wire fences (not electric fences – they are already grounded), metal doors, hay tracks and rails, and metal roofs. Install terminals on cupolas, ventilators, etc. Ground metal stanchions, gates and corral panels. Install lightning arresters on overhead wires. Ground chimneys, stovepipes and vent pipes. Install lightning rods on all silos and ground the silos. Ground metal water pipes, light poles, and sign posts. Bury utility lines, including electric and telephone lines. Avoid traditional suspended lines which are much more likely to be struck by lightning and carry the current directly into a building. Ground metal dog run wires. To protect a tree, you can install terminals, making sure the rod sticks up above the crown of the tree. Alternately, you can put a fence around a lone tree at the drip line so animals won’t gather under it.
Once you have your lightning protection system in place, make detailed sketches and diagrams so that you know where a strike will go to ground. Keep it with diagrams of wiring systems in barns and other buildings.
Emergency actions
If possible, bring animals into shelter if an electrical storm arises. Avoid tethering animals with a metal chain. Don’t use metal-fastened collars or metal chains on animals to left in the open.
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