[TowerTalk] Thoughts on a Grounding System for my new tower

[Jim Lux]

On 9/3/12 9:15 AM, Jim W7RY wrote:
> All your tower and shack grounding questions answered here:
>
> http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCIQFjAA&url=http%3A%2F%2Fwww.radioandtrunking.com%2Fdownloads%2Fmotorola%2FR56_2005_manual.pdf&ei=ZtdEUOzCGureigLcroHgAg&usg=AFQjCNEOc2r04mGLmXraEPGmEoqznH6KJQ&sig2=KVPI276L2uOjwU9r6NuFeA
>



Interesting.. they've got the same IEEE docs, but they don't give much 
rationale for things, other than citing other specs (IEEE, TIA, etc.)

pg 4-12 Here's a potential reason for multiple rods... Contact with 
unfrozen soil

And they recommend the use of Ufer grounds for new construction.

What's odd is for ground rings, they have a thing about rods.. if you 
have rods they have to be no more than a certain distance apart.   Can't 
use just one rod or two...   I'm going to guess that's because the 
purpose of a ground ring is to make the voltage uniform within the ring. 
  Changing the local resistance to the surrounding soil in one place 
will reduce that effect.


Page 4-24 does talk about radials, to be used where there is high soil 
resistivity or bedrock and to help dissipate lightning impulses with 
lower current density.  But that isn't for the ground bond wire between 
antenna site and shack.