[TowerTalk] Ground Rods in rocky soil

[steveg at mtaonline.net]

Hi Bill,

First off, I am not speaking for Motorola, nor do I advocate or advise the
use of this or other Motorola methods or standards.

Motorola's latest R56, Standards and Guidelines for Communications Sites,
makes mention of a grounding plate option.  This plate would expose not
less than 2 sq feet of soil to the grounding plate -- and be placed no less
than 2.5 feet deep.  They mention that if you cannot bury the plate that
deep, reference NFPA 780, section 3-13.1.5 for more info.  Also, several
plates can be bonded together, say around a bldg at the corners and middle
sides, to form a buried ground ring, acting as a ground system.

Personally, plate coupling with something like copper or aluminum plate
plate stock sounds fine to me.  I hope this helps!

Steve, NL7W

--------

After being spoiled by Florida's sugar sand in which you could dig  a hole 
for a base for holes and anchors by hand and drive a ground rod down  by 
"jetting" it, I now live on one of the biggest rock piles in the world.
 
Most of the Big Island of Hawaii has solid lava rock.   Fortunately, my
area 
is a little bit better...a mix of clay, small rocks  and rocks up to a foot 
across, certainly not the kind of stuff easy to get  into.  Sometimes the
layer 
of pure clay is just a few inches thick, in  other places it can be ten
feet 
deep.  Ground rods and copper are  pretty expensive out here and I don't
want 
to experiment losing rods just a  couple of feet into the ground and
getting 
stuck at that depth.
 
I know I can use a backhoe to dig the holes and will have one on the  
property to dig the cesspool, but what is the best way to go getting ground
rods  in? 
 I asked the locals at one of the radio club meetings and they weren't 
much 
help.  Responses were.....most guys just drive it in a foot or so and  use 
radials.  Since the station will sit on a hill, I really don't feel too 
secure 
putting the rod in only a foot, however I do plan on running the radials,  
since I know it will help.
 
Any ideas?
 
Bill K4XS/KH7XS

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