[TowerTalk] Water tower omni

[Red]

The rolling ball does not generate a cone of protection.  It defines a 
volume no higher than the radius of the ball in which there is 
protection.  To define a volume in which protection is 90%, use a ball 
90 meters in diameter.  For 99% protection, reduce the ball to 40 meters 
diameter.

A 23 degree cone under 50 meters high gives about 99% protection; a 45 
degree cone gives 91%.

7e de WOØW

>The 'rolling ball' theory of lightning protection is an ancient method that
>said basically that you take a ball (in your mind of course) as tall as a
>vertical object and roll it around the object and any area inside where the
>ball rolls is safe from lightning... basically it is something like a 45
>degree angle from the highest point down to the ground, also known as the
>'cone of protection'.  this has been shown to be untrue many times,
>photographic evidence of lightning hitting sides of buildings, near the base
>of towers, the bottom wires on power lines, and many other spots that would
>be 'safe' according to the rolling ball theory exist.  
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