Hello Dwight,
The spacing of the ground rods is determined by the length of the rods
themselves. Think of each ground rod as developing a sphere around it with a
raduis equal to its depth e.g. for a 8' ground rod, the radius would be 8'.
This becomes the sphere where current is dissipated for that rod. The ideal
spacing is to set the rods so that their spheres touch, so if the rods were all
8' deep, you would set them on 16 foot centers, the copper strap bonding them
together at the top. The bonding is essential for the system to work so you
should seek something that will not corrode. Cadweld is a process that forms a
"molecular bond" which will not corrode and result in loss of
continuity/conductivity.
May I recommend you obtain a copy of "Lightning Protection and Ground
Solutions for Communications Sites," by Ken Rand at Polyphaser, published in
2000. While some of the data may be outdated e.g. average strike current 18KA
is now thought to be much higher, the principles are solid. This is one of the
best single reference books I've found on the subject. The cost is $20.00 and
it's an easy read.
I am going through the same issues as you are with my new tower system as
well.
73,
Mike DiGirolamo, W4XN
Charlottesville, VA
-> . Message: 12
-> . Date: Sat, 22 Jul 2006 06:20:19 -0500
-> . From: DGB <dwibos@netnet.net>
-> . Subject: [TowerTalk] Copper Strapping Clamps
-> . To: towertalk@contesting.com
-> . Message-ID: <44C209F3.20403@netnet.net>
-> . Content-Type: text/plain; charset=ISO-8859-1; format=flowed
-> .
-> . I'm in the process of putting up a tower and grounding
-> . system for
-> . lightning. I purchased a good quantity of copper
-> . flashing at a scrap
-> . dealer and trimmed down to 1-1/2" straps.
-> .
-> . After considerable research on the 'net the only clamps
-> . I've found for
-> . fixing the runs to copper ground rods are the ones made
-> . by polyphaser
-> . available for around $14 ea. I've several of these
-> . connections to make
-> . so the cost would be prohibitive. Haven't been able to
-> . locate any
-> . Cadweld products for copper strapping to evaluate the
-> . cost of that
-> . process. What homebrew cost-effective methods have
-> . others used for a
-> . good long-lasting contact? My soil is sand.
-> .
-> . Also in the those long runs interconnecting everything,
-> . such as the
-> . house power entry point, the shack power entry point,
-> . and the ground
-> . window for the shack, should I be installing ground rods
-> . every sixteen feet?
-> .
-> . I've had wires up here at this location in northeast WI
-> . for 15 years
-> . with never a hit, but I just know when I get this tower
-> . up, it will find me!
-> .
-> . thanks ... Dwight W9YQ
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