In article ,
"Szczepan Bialek" wrote:

"Dave" wrote
...
On Oct 22, 8:40 am, "Szczepan Bialek" wrote:

.
..
On Oct 21, 2:49 am, "Szczepan Bialek" wrote:



1. If "The intention is to PREVENT a direct lightning strike," - many
sharp
needle is used,
Good luck.

2. If the intention is to CATCH a direct lightning strike and conduct a
strike to ground - a polished big ball is used.
S*
Good luck.

The above apply to grounded tower.

For:
" But, is there a difference in strike rate between grounded and
ungrounded towers of the same height. I would think that the difference
would be very small, and smaller as the height gets bigger."
You wrote: "I'd rather have a grounded mast struck every 5 years with no
damage,
vs an ungrounded mast struck every 10 years that led to heavy
damage or even burned the house down.
So worrying about that is kind of silly I think, when you know
an ungrounded mast is big trouble if it ever does get hit."

The grounded tower catch the electrons in form of "electron conveyer
belt"
and lightning. If the "belt" is efective enough no lightnings. All local
excess of electrons from the cloud flow without lightning. If no, the
lightning appears but it is weak (the sum of electrons is the same).

The strike in the ungrouded tower is always strong.
So You are right.
S*

no, that is not right. a grounded tower can not dissipate enough
charge to reduce the stroke intensity. towers actually attract MORE
high current strokes than the surrounding ground.

Grounded towers with the many spikes dissipate more charge then the simmilar
towers with the polished big ball.
That with the many spikes PREVENT (or minimalise), that with the balls CATCH
(high current strokes).

Much of this is speculation.

With 10 million volts; currents of 10,000 amperes and strokes that can
travel 30 miles: whether you have a ball or a spike on top of a roof
isn't going to make much difference.

It has been shown that a properly installed lightning rod system; and UL
rated materials connected to low resistance grounds will increase the
odds of protecting lives and property substantially.

(The TV stations on top the Sears tower in Chicago continue to transmit
even as they are being struck.)