In a message dated 7/28/02 2:46:41 PM Pacific Daylight Time, ford@cmgate.com
writes:
> Watching and learning from this thread, I'm beginning to think I should be
> operating from a metal dog house with a ring of ground rods directly at the
> station equipment (sarcastic). I've got about 6' of ground buss running
> behind the operating position. Total distance to the rod is about 6'-7'.
I
> fail to see how it can get any better than this, short of the metal dog
> house approach.
>
The main idea of grounding (and in particular the Single Point Ground
System) is to keep the lightning transients OUT of the building. The
inside-the-building equipment ground is only secondarily important; if you do
a really good job on the SPGS, you could probably get away with doing little
or no grounding inside.
If your 6' of ground bus is a wire (as opposed to solid strap) then it
has enough inductive resistance (I think that's the value - I could be wrong)
that it doesn't offer a low resistance path to ground and is of marginal
value and effectiveness.
> I think what all respondants to this thread are saying is that if you get a
> close strike, you are TOAST!
Not true. If you get a close strike and you have 'adequate' protection,
then NOTHING will happen.
> Trying to engineer for a direct hit is
> impossible with the light gauge metals and structures that are quite flimsy
> when compared to a bridge or a sky-scraper.
Apples and oranges, dear boy. It's relatively easy to engineer for a
direct hit - professionals do it everyday. And hundreds of sites take direct
hits everyday with no damage. The techniques and materials are well
documented.
>
> How about some practical advice for the 90% of hams that cannot possibly
> engineer a perfect solution. A second floor shack is TOAST. What should
> this guy do to protect his family and possessions? Forget the radio! I'd
> expect a sensitive piece of equipment to fry in the presence of a million
> volts at a million amps. I would rather have that insured equipment
> completely melt down and fry while shunting most of the strike to ground
> rather than burn 100% of my worldly possessions.
>
Not much factual information in that paragraph. I suggest you get the
Polyphaser book and start reading there for real information and not get all
excited with wild speculation.
Cheers,
Steve K7LXC
TOWER TECH --
Professional tower services for commercial and amateur
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