[TowerTalk] ground rods for towers

[Joe Reisert]

Adam,

A few years ago I discussed this same problem of rocky soil and rocks with 
Roger Block, former owner of Polyphaser. My land mostly consists of a thin 
layer of soil on top of rock (NH is the Granite State!) and I can't drive a 
stake even 2 feet down!

So, for this type of soil, Roger did some tests and recommends that you use 
1-1/2" wide thin (.015" thick) copper strapping. The best plan is four (4) 
straps 50 feet long 90 degrees apart. Above 50 feet has diminishing results.

Polyphaser sells this recommended copper same strap. However, I bought mine 
from Metal and Cable in Twinsburg, OH (who was less expensive) for about 
$25-30 for each 50 foot strap. Pretty cheap protection and it also becomes 
part of my grounding system for shunt feeding the tower on 160 meters.

Furthermore, all you have to do is lay the copper straps right on the 
ground! I bolted my four (4) copper straps to a brass plate that is in turn 
strapped to the base of the tower with a piece of the same copper strap. It 
probably would be OK to just attach each strap directly to a tower leg with 
a few hose clamps.

73,

Joe, W1JR

At 08:28 AM 7/31/00 -0500, Adam Adkins wrote:



> > -----Original Message-----
> > From: owner-towertalk@contesting.com
> > [mailto:owner-towertalk@contesting.com]On Behalf Of K7LXC@aol.com
> > Sent: Monday, July 31, 2000 8:11 AM
> > To: w4th@webtv.net; towertalk@contesting.com
> > Subject: Re: [TowerTalk] ground rods for towers
> >
> >
> >
> > In a message dated 07/31/2000 12:09:51 AM Pacific Daylight Time,
> > w4th@webtv.net writes:
> >
> > > How many ground rods should be used on a tower of 75 feet? This tower is
> > >  used only for beams and dipole support. I have a friend who says one is
> > >  enough, I have others who say one on each leg, what say ye me hearties?
> >
> >     Since you're in a spot that gets a significant amount of
> > lightning, I'd
> > be sure to do a decent job. Three ground rods per leg spaced a rod-length
> > apart is a good start.
>
>         I assume you are talking about 8' ground rods.  Here's a question 
> regarding
>about getting adequate protection from those ground rods when you live in an
>area that has very rocky soil.
>
>         Actually, although the soil is very rocky, that isn't the major 
> problem.
>The biggest concern is the solid rock that is about 24" down from grade.  It
>is impossible to drive a ground rod vertically into that rock.  Can I borrow
>a trick from the electrician's trade and bury the rods horizontally in
>trenches to get the same kind of lightning protection?  And if so, how far
>apart should they be spaced?
>
>         Thanks!
>
>73,
>
>Adam Adkins, KM5N
>
>
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