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Re: [TowerTalk] CATV & Phone grounds

To:, TowerTalk <>
Subject: Re: [TowerTalk] CATV & Phone grounds
From: Red <>
Date: Tue, 11 Jul 2006 10:45:14 -0500
List-post: <>
Good point, Don.

The ground potential, voltage on the ground wire, for the power company 
may have risen during the strike because it (and your station ground 
that was tied to the power company ground) was discharging the transient 
from the strike.  Lightning arrestors or surge suppressors on those 
systems limited the voltage difference between power lines, feedlines, 
and associated ground.  Meanwhile, potential on the cable and phone 
systems, not referenced to that same ground, didn't rise and a large 
voltage difference developed between those systems and the power system 
they connect to at appliances like the TV, phone modems, wireless 
phones, etc.

This is a reason for tying all ground systems together and limiting the 
voltage on all ungrounded lines with surge suppressors.  If everything 
is at the same potential, within normal limits, no damage will be done 
even if the voltage references rises to thousands of volts, just short 
of the level at which discharges to other systems like plumbing or 
corona discharges to air occur.  The eagle perches on the high voltage 
transmission line but is not injured until it puts a foot or wind in 
contact with a conductor at a different potential.

73 de WOØW wrote:

> to tie their  
>ground to the ground at the service entrance?
>Mine are not.
>Several months ago my tower took a lightning hit and everything tied to the  
>phone and cable lines was *killed*. I wonder if not having their grounds tied  
>into the power co's is the reason.
>73, Don - K4BEV

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