[Towertalk] grounding system

[K7LXC@aol.com]

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