Thanks Shawn. Saved.
When I read Steve K7LXC's book "Up The Tower ...", I got the impression that
it's best to at least try to pull a permit. The reasons vary from defending
against neighbors who don't like towers to liability. So, I looked into it.
When I arrived for the meeting with my county representatives to hand-off the
PE's documents, they expressed surprise. One rep said that, in twelve years,
she couldn't recall even ONE ham tower permit (my county has about 2K hams). It
appears the biggest resistance is gubmint interference and cost. I found the
process was neither terribly difficult nor costly.
My ground system currently exceeds the PE's drawing and NEC requirements. I
intend to add more copper in the ground
vy 73,
Bryan WA7PRC
Date: Tue, 3 Feb 2015 16:37:34 +0000 (UTC)
From: N3AE
Subject: Re: [TowerTalk] [Bulk] Antenna to Shack Ground Connection
I just passed the local electrical inspection for my tower a few weeks ago.
Around here, it's rare that anyone pulls permits for amateur radio towers, so
all of this was a bit new for the inspector. Our county follows the 2011 NEC
and Article 810 of that version is what he was using. Apparently, he just
wanted to see two things. He wanted to see the tower ground rod (yes, currently
just one) bonded to the nearby (10ft away) ground rod from my detached garage
sub-panel, and he wanted to see the coax shield grounded at the base of the
tower (used one of KF7P's very nice coax grounding plates). The tower is
grounded its nearby rod using 2" copper strap and KF7P strap clamps, stainless
at the tower and copper at the rod. I used solid #4 to bond the two ground rods
together. The tower foundation is a UFER, having the rebar cage bonded to the
tower anchor bolts using listed direct bury clamps and #4 copper. The
electrical inspector never asked about the foundation/UFER.
Search "Challenging Grounding/Bonding Situation" in the archives for a
description of my installation. That thread unfortunately got hijacked to
discuss requirements for grounding subpanels.
So the inspector was happy, but I'm not. I still plan on additional ground rods
in a fan around the tower plus a run of bare #4 copper from the tower to the
ground rod at the service entrance of the house almost 200 feet away. Using #4
more for mechanical durability reasons than electrical. Plus the usual "SPG"
entrance panel at the house bonded to the overall system ground. I also plan on
a transient suppressor at the base of the tower for the rotor cable and coax
transient suppressors at the entrance panel.
For what it's worth, one of the better articles I've found on antenna grounding
and bonding per the NEC can be found at:
http://www.reeve.com/Documents/Articles%20Papers/AntennaSystemGroundingRequirements_Reeve.pdf ;
Interesting side note: 2011 NEC Article 810 says you have to have a "listed
antenna discharge unit" unless the coax shield is grounded. As far as I can
tell, none of the common 50 Ohm coax transient suppressors (Polyphaser,
Alfa/Delta, I.C.E) are "listed." I've not seen a U.L. sticker on any of them.
Guess if you had a really finicky inspector he might get you on that. But the
Code gives you a way out by grounding the coax shield, which is good practice
anyway.
Shawn
N3AE
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