[Boatanchors] new Ground system

Fri, 15 Mar 2002 11:09:52 -0500

I was afraid you were going to say that Glen. I would bet you 10:1 that
your tower has been hit many times given the location that you describe
it is located in. It sounds as though you have very good grounding
installed. That is the key to keep from damaging things. As far as the
dissipation devices go, I don't know how to put it any nicer, they are
snake oil.

There is no way to "bleed of the charge". This is an old myth and it has
been propagated by the manufacturers of the dissipation arrays in the
past several years.
If you will notice that in their installation instructions that they
recommend quite extensive grounding to make them "work properly". Wonder
why?

The thing is that the earth can supply hundreds of times more energy
much faster than it can be bled off.

NASA and the FAA tested some of dissipation devices extensively a few
years ago and determined that there was no difference in the number or
severity of strikes with or without the dissipation arrays. I have some
video tape of some test's that the FAA did on one of their towers
showing an actual strike hitting the dissipation device.

If you want to find out how often your tower really gets hit you can
install a simple lightning strike counter. You can make one with a small
veeder root counter that is activated by a coil. Put an mov across the
coil to keep from cooking it. Hook one lead to any point on a tower leg
and go up several feet and hook the other lead. During a strike the
current that is developed across the section of tower leg will trip the
counter one count. Polyphaser sells such a device for that purpose also.

There is no way to prevent a lightning strike. There are however many
ways to control the strike current once it does hit.

I have a few notes about lightning protection that I posted to another
group awhile back if there is interest here.

73
Gary  K4FMX

Glen Zook wrote:

> My tower has NEVER been HIT by lighting.  However,
> there is more to this than just grounding.  You have
> to use dissipation devices as well.  Those can be made
> for under $10 apiece (one is needed for each leg of a
> tower, and if the tower is over 100 feet tall, they
> should be placed from 50 to 75 feet apart up each
> leg).  Or, you can buy them commercially built for
> about $350 apiece!
>
> A dissipation device will not protect a tower 100%
> from a strike (nothing can).  However, they can reduce
> the chances of a strike up to 99.99%.
>
> Glen, K9STH
>
> --- Gary Schafer <[email protected]> wrote:
> > Glen,  are you saying that because of your grounding
> > system that your
> > tower has never been hit by lightning? Or that you
> > have never had any
> > damage from a lightning strike.
>
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