"w_tom" wrote in message
...
Unfortunately Frank Gilliland has exaggerated his numbers
due to insufficient experience and too much time listening to
myths. His numbers will be exposed as fiction.

Field experience says repeatedly that antenna and radio can
suffer direct strikes without damage. That is proven about 25
times every year atop Empire State Building since the 1930s.
According to Frank, they must suffer damage 25 times per
year. Let's start with his numbers.

Millions of volts? Yes. But same voltage does not appear
everywhere in a circuit - basic circuit theory. Those
millions of voltage are in the sky. Surge protection is about
making those millions of voltage appear elsewhere which is why
industry professionals discuss impedance. A low impedance
connection to earth means no millions of volts.

Millions of amps? Only in dreams. Most lightning is below
20,000 amps and of such short duration as to not be high
energy. Lightning typically so low energy at the strike
location (not to be confused with what is miles above) that
well over 90% of all trees struck leave no indication of that
strike.

How big need a wire be to shunt (earth) lightning? Even the
US Army training manual TM5-690 requires 10 AWG wire to
conduct the direct lightning strike without damage. Same wire
found in 20 or 30 amp AC electric boxes because lightning is
not the millions of amps so often claimed in urban myths.
Unlike Frank, numbers are provided by multiple, reliable
sources.

Another who does this for a living:
From Colin Baliss "Transmission & Distribution Electrical
Engineering":
Although lightning strikes have impressive voltage and current values
(typically hundreds to thousands of kV and 10-100 kA) the energy
content of the discharge is relatively low ...

or Martin A Uman in All About Lightning
Most of the energy available to the lightning is converted along
the lightning channel to thunder, heat, light, and radio waves,
leaving only a fraction available at the channel base for
immediate use or storage.

In short, Frank Gilliland's numbers are classic myths.


Pre WWII ham radio operators demonstrated what was required
for protection. First they would disconnect antenna and still
suffer damage. Then placed antenna lead in a mason jar, and
still suffered damage. But when antenna was connected to
earth ground, then no damage. Neither a mason jar nor "one
of those big blade switches" sufficiently blocks destructive
transients. Of course not. Lightning was not blocked by
miles of air. Is a mason jar or knife switch to do what miles
of air could not? Of course not. For no damage, provide the
destructive transient what it wants - earth ground.

zeeeeeeee's antenna installation is demonstrated by a
figure in TN CR 002 The Need for Coordinated Protection
(corrected URL)

http://www.erico.com/public/library/...es/tncr002.pdf

Need anyone suffer damage from direct lightning? Of course
not. Such damage is considered a human failure because proper
earthing is so effective and so inexpensive.

So, you claim that ALL lightning strikes can be safely shunted to Earth,
with no damage along the path? Well, I don't have 30 years experience in the
electrical transmission and distribution industry, but I do have 25 years.
And I have seen properly earth grounded transmission and distribution poles
where the awg #6-#4 CU wires were mostly vaporized. Sure, there were bits
and short pieces left, but for the most part, the wire was gone. I confer
with you most of what you say, but you would be not completely honest to say
that all lightning strikes can be earthed with no damage. Possible? Maybe.
Practical? Nope.There will be strikes of magnitude where practical
techniques fail.