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Understanding Lightning and what to do about it.

 

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NOTE:  This is one persons opinion, and because the world is sue happy I place this disclaimer at the top of this article.  Use this information at your own risk..

Lightning seems to be poorly understood by a great many of us, that is why I write this article.  The information here is compiled from many sources.  Many of them real world experiences including by my own, and by talking to many other radio operators, professional tower installers, including commercial sites.

A little History of my own

Some time back a church had their own radio station in which I was involved.  It was on a 100 ft. tower with a commercial FM broadcast antenna. Repeatedly the station was damaged by lightning and I was consulted on what to do.  I  told them to buy a "Christmas Tree" (common venacular for a commercial lightning arrestor for large tower installations like television)  They said it was too expensive and wanted an alternative solution so I gave them one.
I told them to put four 50 ft. wires, attached to the top of the tower just below the antenna.  Each wire spaced about 90 degrees apart, and attached to nearby trees for support.  Next I told them to ground the tower with wire laying on the ground in a similar fashion as on the top of the tower but to add as many wires as they could afford. (The tower was on a mountain and poor ground for conductivity).  They put several 100 ft. wires, attached to the base of the tower on the ground and let nature bury them. 
After the above was done, they never had another lightning related failure or problem.

Here is the reason why?
Notice the picture on the left, it represents a tower or any other conductor on the ground. When a lightning bolt occurs, it produces a massive energy wave capable of enough energy to cause fires, and literally blow equipment apart, even buildings. On the left notice that when the energy wave strikes the tower, ALL of the energy contained in that part of the wave that contacts the metal is instantly transferred to the tower.  If the tower is not grounded the energy will find another way to ground, usually what ever is closest, and bleed off the energy causing damage or worse.  If the tower has a poor ground, the situation isn't much better, at least some of the energy will dissipate in nearby objects, like your radio!   Now look at the picture on the right.  With a conductive horizontal surface, a beam antenna or some other spread out conductor, connected to the tower top, the energy wave makes contact FIRST, with the outer edges of the conductor/s extending out from the tower itself.  This gives the energy a path to discharge on, BEFORE the energy wave actually makes full contact with the tower.  Thus bleeding the energy off before it can build up fast enough to cause damage.  This requires a good ground to function properly.  That is why I told the church people to put ground wires on the ground connected to the base of the tower.  This forever eliminated lightning induced damage.  Similar results have been reported by many operator.  So grounding your tower will at least provide some protection, if you are unsure of your ground/soil conductivity, I would suggest you place a few 12 ga. wires in the ground radiating away from your tower or what ever object you want to protect, at least 4 wires 90 degrees apart if you can, and 100 ft. long.  Use whatever length wire you have if nothing else.  Every little bit helps in poor ground. I believe the church used 8 wires on the ground.  Note, some people poor salt on the ground, and this works, but depending on rain and soil material, it will wash away and leave you unprotected at some point.


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