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Re: [TowerTalk] CATV & Phone grounds

To: "'JC Smith'" <jc-smith@comcast.net>, <towertalk@contesting.com>
Subject: Re: [TowerTalk] CATV & Phone grounds
From: "Gary Schafer" <garyschafer@comcast.net>
Date: Tue, 11 Jul 2006 15:49:41 -0500
List-post: <mailto:towertalk@contesting.com>
If you run them into conduit you need to ground them to the conduit or they
will arc.
It is best to ground all cables to the base of the tower and also at the
shack entrance where protective devices should be placed on the lines and
grounded.

73
Gary  K4FMX

> -----Original Message-----
> From: towertalk-bounces@contesting.com [mailto:towertalk-
> bounces@contesting.com] On Behalf Of JC Smith
> Sent: Tuesday, July 11, 2006 2:45 PM
> To: 'Jim Brown'; towertalk@contesting.com
> Subject: Re: [TowerTalk] CATV & Phone grounds
> 
> Here's a thought (probably mentioned previously).  Assuming a tower has a
> good ground system, we still have cables connecting the antennas and other
> equipment on the tower to the house and electronics in the shack.  We want
> to minimize (or eliminate) any lightning following these cables into the
> house.  I know there are fancy commercial systems for this but how about
> bolting a 10' length of galvanized pipe to the tower leg and running the
> cables through it?
> 
> 73 - JC, K0HPS
> 
> 
> 
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com]On Behalf Of Jim Brown
> Sent: Tuesday, July 11, 2006 11:55 AM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] CATV & Phone grounds
> 
> On Tue, 11 Jul 2006 10:49:32 -0700, Jim Lux wrote:
> 
> >How to tie really depends on why you're tying.
> 
> Yes. If you think of lightning as DC, you're likely to be in
> serious trouble. IEEE studies show that the energy content in
> lightning has a broad peak around 1 MHz, with significant
> content well above and below that range.
> 
> This means that the most important consideration is the
> INDUCTANCE of the network of conductors that tie to each other
> and complete the path to earth.
> 
> To answer the original question -- YES, all of these "grounds"
> should be tied together by paths having the lowest possible
> inductance. That means SHORT conductors, and WIDE conductors.
> As others have noted, braid and stranded wiring is bad because
> it corrodes much more quickly than a solid conductor. That's
> why wide copper strap is preferred for RF bonding.
> 
> Ideally, from a lightning protection point of view, telco,
> CATV, power, and our ham antennas should all enter the premises
> at the same point so that the bond between them can be very
> short.
> 
> In the real world, that doesn't always happen, and the bond
> between them may need to either run through the footprint of
> the house to be short, or must run around the perimeter. That's
> another argument in favor of multiple ground electrodes (rods)
> around the perimeter of the building, all tied together in a
> ring.
> 
> It's also important to realize that Standards and Building
> Codes are influenced by political and financial interests (like
> power companies, telephone companies, and CATV companies).
> That's why the requirements for bonding of telco and CATV
> wiring are so lightweight.
> 
> 73,
> 
> Jim Brown K9YC
> http:audiosystemsgroup.com
> 
> 
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