[TowerTalk] Lightning protection - length of grounding rods

[Jim Lux]

On 1/29/15 6:51 AM, Ed Sawyer wrote:
>
>
> Number 4 is really where all the payoff is and it's a system of ground
> points both in the tower area for tower hanging electrical items, at the
> entrance to the house, and a grounding system in the shack.  Number 4 is
> actually the most utilized need in my experience.  At this QTH, I have had 6
> strikes of note in 10 years.  1 was a direct hit on my shortest tower
> (proving other points), 1 was an energetic leader that did not result in a
> direct hit but blew out coax on the 30 ft EU 10M antennas that decided it
> wanted to be the leader that day, and 4 (or more actually) have been close
> ground strikes that have seriously affected ground potential not equaling
> zero volts.
>
>
>
> I admire the survivability and reliability demonstrated by a nearby cell
> tower installation that I hike up to at 2600ft (my QTH is at 1200 ft and yes
> it does cut off my Pacific low angle stuff).  But when I see the money put
> into the hardline, grounding, and equipment shack at that installation, it
> quickly becomes apparent that duplicating that "ain't gonna happen".
>
>


This is why I sort of cringe when folks hand out links to the Motorola 
R56 document or the FAA document and say "here's what to do for 
lightning protection"..

That's well, well beyond what most amateurs need.

The other thing about commercial vs amateur practice is that the job 
cost structure is totally different.  Amateur self-labor is 
out-of-pocket free (leaving aside opportunity cost, etc.).. Electrical 
contractor labor is not. Amateurs have a reputation as excellent 
scroungers and improvisors and collectors over the years of materials. 
Electrical contractors buy their materials at current cost, today.

For a contractor to drive a half dozen rods and string another 30 feet 
of copper wire and one-shot weld it is a small material cost compared to 
the labor.  They do not care all that much whether the drawing calls for 
3 rods or 6.