[TowerTalk] Naive question about lightning protection

Mark . n1lo@hotmail.com
Tue, 08 Aug 2000 09:39:45 EDT


Sylvan asked:

<<..snip..QUESTION: Could I put an automobile spark plug at the base of each 
tower leg? The gap is easy to adjust, they are cheap to replace and simple 
to mount. tnx Sylvan >>

A spark plug will not handle the tremendous current generated during a 
lightning strike. It would handle induced surges from nearby strikes on open 
wire feedlines, at much lower magnitudes, and perhaps small streamer 
discharges on your tower, but my intuition tells me it would be handily 
melted away by even the smallest of direct strikes.

Upon further thought, I will throw out this suggestion, using commonly 
available materials and Ham frugality (cheap!). Let's expand on Tom's  
copper pipe idea.
Now suppose you pound 12 inches of the end of the pipe flat, creating a 
sharper edge on one side, and place this edge parallel to the tower leg. 
This, in effect, creates a large, parallel path for potential arcs that will 
form sooner that on the more rounded, un-flattened edge.
You might even use a mating copper edge clamped to the tower leg, such that 
both sides now have sharper edges from which an arc will jump even easier.
Just some more brainstorming. Perhaps this is unnecessary, but the sooner 
your arc forms, the more surge will be shunted away from your feedlines at 
the bottom.
Sounds like you received many ideas direct. Thanks for posting the summary, 
so that the TowerTalk archives will carry people's ideas. The more we post 
to the reflector, the more people can learn from searches.

Good luck with your project, Sylvan.

--...MARK_N1LO...--

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