Ed:
I'm planning on putting the arrestors at the base of my tower, bolted
to the insides of a metallic Hoffman box or similar. From the box the coax
and control cable runs will be in 3 inch sch 40 buried conduit to the
house/shack. The alternative is to put the arrestors in a box just outside
the house at the end of the conduit run and ground at that point, as most
commercial installations have it.
My thinking is that the ground field for a lightning strike originates
at the tower, where all the underground radials connect to the tower legs.
Here the inductance of multiple parallel ground legs will be less than at
the entrance to the house/shack, fifty feet from the tower, where I will
have only one radial to which to connect the arrestors' grounds. (I'm not
planning on encircling my house with buried copper ground wires.) I'd
rather have the arrestors far away from the house and let them do their work
in a low-inductance part of the ground field, rather than close to the
house.
I agree with Steve, though - keep the single-point ground outside of
your house. Its connection into earth will be shorter and the lightning
energy is less likely to get into your house wiring. And don't put a bend
in your ground wire from the coax runs. Keep it as straight as possible
such that the lightning energy continues to move in a downward direction to
a metallic ground connection.
GL es 73 de
Gene Smar AD3F
-----Original Message-----
From: Milcarsky <jamvet@bellsouth.net>
To: TowerTalk <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Friday, July 20, 2001 7:03 PM
Subject: Re: [TowerTalk] Routing cables - tower to shack
>
>Steve,
>
>It's clear that grounding the coax at the tower base, before it bends
toward
>the shack is the right thing to do. However, I have only heard that the
>coax shield should be grounded at this point. Why not also place an
>arrestor for the center conductor at this point as well? It would seem
that
>this would afford a certain amount of extra protection. What are your
>thoughts?
>
>Ed KG4ARN
>
>----- Original Message -----
>From: <K7LXC@aol.com>
>To: <kq2m@mags.net>; <towertalk@contesting.com>
>Sent: Friday, July 20, 2001 6:14 PM
>Subject: Re: [TowerTalk] Routing cables - tower to shack
>> Commercial specs call for grounding cables that come down the tower
>> *before* they turn towards the building. The cables should be grounded
>> directly to the tower at that point to offer the lowest resistance path
to
>> ground. The bend in the cables introduces inductance at that point so you
>> want to be grounded before that so the lightning energy will go there to
>> ground.
>
>
>
>
>List Sponsor: Are you thinking about installing a tower this summer? Call
us
>for information on our fabulous Trylon Titan self-supporting towers - up to
>96-feet for less than $2000! at 888-833-3104 <A
HREF="http://www.ChampionRadio.com";>
>www.ChampionRadio.com</A>
>
>-----
>FAQ on WWW: http://www.contesting.com/FAQ/towertalk
>Submissions: towertalk@contesting.com
>Administrative requests: towertalk-REQUEST@contesting.com
>Problems: owner-towertalk@contesting.com
>
List Sponsor: Are you thinking about installing a tower this summer? Call us
for information on our fabulous Trylon Titan self-supporting towers - up to
96-feet for less than $2000! at 888-833-3104 <A
HREF="http://www.ChampionRadio.com";>
www.ChampionRadio.com</A>
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|