I went through ALL of this about five years ago and it's ALL good.
So, to put a more physical view to this I've posted some of my pix to
http://picasaweb.google.com/kc2tnpix on how I accomplished the installation.
It's not cheap but I sleep a little better.
Joe - KC2TN
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of Phil Camera
Sent: Tuesday, September 11, 2007 4:32 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Lightning Advice/Ground Potentials
I'll attempt a more non-technical explanation for why you need all your
grounds (Tower, SPG, Shack, Electrical, Arrestors) to be bonded together.
Say that you have all of the above bonded together except for the Electrical
service entrance. We get strike energy induced into our Tower/Antenna
system. Most of the energy will be shunted to ground out at the tower, and
then some more at the SPG (arrestors or just coax shields bonded to the
SPG). Some voltage rise will still occur in the system and will go onto the
case of the equipment inside via the Shack ground.
Now the electrical service ground is not in this group and will/may have a
lower potential (yes it will have some energy induced from the nearby strike
but not the same as the Tower/SPG/Shack system) than the Tower/SPG/Shack
system.
Now inside your equipment you have your case at a higher voltage than the
electrical ground (which is connected to your mains box and in turn to your
service entrance ground). Back from Electricity 101, we know that when we
have a voltage difference and there is a conductive path, we will have
current flow. This flow is normally through some component on your
equipment's circuitry or circuit board and voila, zapped equipment.
OK, so now lets bond everything together, outdoors. Now when we ge the
induced energy, everybody (grounds) all rise and fall in that voltage
together and there is no voltage difference inside of your equipment and
voila, no current and no zapped electronics.
Quite simple if you think about it.
--
Phil - KB9CRY
Lockport, IL
http://nidxa.org/memberWWW/kb9cry_home.htm
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