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Re: [TowerTalk] Cadweld vs clamps

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Cadweld vs clamps
From: Jim Lux <jimlux@earthlink.net>
Date: Thu, 23 Oct 2014 15:39:39 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 10/23/14, 11:34 AM, Bill Turner wrote:
------------ ORIGINAL MESSAGE ------------(may be snipped)

On Thu, 23 Oct 2014 06:49:13 -0500, Keith Dutson wrote:

My experience shows the difference is time.  No clamp can be expected to
maintain its contact area with the wire and rod in soil over a long period
of time due to chemical reaction between the soil, wire, clamp and rod.
Cadweld solves this problem by isolating the chemical action to external
parts of the connection.

REPLY:

First, I wouldn't worry about a few microns of corrosion, especially
when lightning is concerned. A lightning bolt has already traveled
thousands of feet through an insulator (air) - another thousandth of
an inch of corrosion is nothing.


I would worry about Intermodulation from a corroded connection. From a lightning protection standpoint, you could have a layer of tape in between: it will punch right through. Static charge or induced voltages would be a problem.

And, many hams use their electrical safety ground as a double/triple duty vertical antenna ground/lightning ground. Whether that is a wise idea I leave for another discussion. I tend to think that one should keep the functions separated, and might even advocate for RF choking in the required bonding jumpers between grounding systems (although I believe someone pointed out that a suitable choke might be impractical)


Second, as someone pointed out, the clamp itself should not be buried,
for two reasons. One to reduce corrosion and two, to permit
inspection.


I think it's the latter that drives the code requirements.

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