[TowerTalk] Verticals and well pipe grounding

[Roger (K8RI) on TT]

In the Saginaw Valley, which is an extremely large (perhaps close to, or 
more than  6,000 sq miles and ringed by roughly 600 ft hills-shown on 
Google Earth)  is shallow valley off  the SW end of Saginaw Bay in 
Michigan. The top  soil varies widely, but generally is no more than a 
foot or two thick.  The sub soil is "usually" clay, or sand (possibly 
layers of both) usually for 6 to 10 feet.  Below that is usually about 
400 feet of gravel, sand, and large rocks over shale. On the surface 
those rocks would be called erratics.  In our area there is a wide area 
of salt water at roughly 100 feet down, but that varies widely  from 50 
feet to over several hundred feet, over short distances.

*IOW, the soil in this area generally makes for a poor ground, so an 
effective, safety ground system needs to cover a relatively large area.  
The one, two, or three ground rods required at the electrical entrance 
are often relatively useless as safety grounds. In late summer they 
don't come near the water table in some locations (mine)**
**
**Even though the water table may be within a few feet of the surface 
part of the year, three, 8' or 10' ground rods around the base of a 
tower, often make for a poor safety ground and are not suitable for 
lightning protection, **
*
Many hams in this area use only one or two Ground rods at the base of 
the tower,  sometimes, none.  There are several 40 to 60 ft towers 
within 3 miles of me with no ground rods.  I took down a simple 30 
footer on a sand hill that had no ground rods. The rational was that it 
was dry sand as far as any ground rod would reach.  It was a fine sand, 
what we usually refer to as "blow sand". A temporary tower for a few 
years and he didn't have the money for a ground system.  With 
thunderstorms in the area he said he'd just throw the cables out the 
window.

I believe there many in this area that just can't afford a good ground 
system  and much of their stations consist of old, scrounged, or basic 
home built equipment.  I know, that 55 years ago, as a 20 year old about 
to turn 21, mine was that way.  Much because I couldn't afford it and 
much because I didn't know any better.

  73

Roger (K8RI)

On 2/7/2016 Sunday 12:47 AM, Jim Brown wrote:
> On Sat,2/6/2016 4:22 PM, jimlux wrote:
>> Using N6LF's formulas I get skin depths around 5-10 meters at 2MHz 
>> (0.005 S/m, epsilonr = 3-10)
>>
>> You might get 60 feet (20 meters) if the soil is particularly 
>> non-conductive (rock).  Dropping the conductivity to 0.5 mS/m gives 
>> you skin depths of 22-34 m at 2MHz 
>
> Rock and sand are quite prevelant throughout the west, and pretty much 
> what we have in the mountains. :)
>
> 73, Jim K9YC 


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