[TowerTalk] Lightning and ground systems

[John D. Peters]

Charles H. Harpole wrote:
> 
> Steve, until you have seen lightning take a path TO ground and AWAY from
> ground in the same hit as I have, you will continue to think that
> disconnecting your radios from all outside wires and wiring is "only in
> your head."
> Lightning is just too freeky for us humans --so far--  completely to
> understand.  De K4VUD
> 
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Well, I dunno.  Lightning is only electricity.  Static electricity for 
sure, but only electricity.  It really does follow Ohm's law just like a 
AA battery type electricity.

You certainly CAN create the same voltage, and identical effects in a 
lab.  You certainly CAN control and influence what lightning will do.

Superstitious behavior and thinking you can do nothing, is not the best 
preparation.  

You really only have to worry about OHM's law.  You either keep the 
voltage low enough to avoid a strike.  OR you control the impedance of 
the available paths.  Both systems DO work.

Disconnecting your coax at the radio will not do much for you if the coax 
is at a voltage sufficient to leap tall buildings in a single bound. If 
you ground that coax so the strike decides to follow the coax to ground 
"You'll be sorryyyyy" if you didn't ground it outside the house.

Why is "keep the lightning outside" so hard to understand?  I guess I 
just don't understand magic.  Natural lightning is "cloud to cloud" 
"cloud to ground" and/or "ground to cloud".  Indeed once the path is 
ionized you might expect ground to cloud and cloud to ground on the same 
path.  You can not predict the path the strike will follow.  It may hit a 
tree, a power pole, a building, or your tower (IF you have not acted to 
prevent the strike voltage buildup.)  If you are taking action to merely 
keep the strike outside, you should EXPECT the strike to hit your tower, 
and prepare for the strike.  

If you expect the stike to hit your tower, is unscrewing the coax all you 
really want to do?  The Polyphaser book is worth buying, and there are 
many other good books on lightning and EMP....check a good library.

73 John K1ER

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