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Re: [TenTec] Re. [Ten Tec] Grounds

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] Re. [Ten Tec] Grounds
From: "George Allgood" <myp4k69@bellsouth.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Tue, 24 Jan 2012 17:11:16 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Hi Stuart.   I keep seeing the word BONDED.  I wonder if that means some 
system other than soldering the conductors together?   What's your method of 
bonding these ground connections?  Thank you.
----- Original Message ----- 
From: "Stuart Rohre" <rohre@arlut.utexas.edu>
To: <tentec@contesting.com>
Sent: Tuesday, January 24, 2012 3:47 PM
Subject: Re: [TenTec] Re. [Ten Tec] Grounds

> Technically, a ground wire covered by the deck is a violation of the
> National Electrical Code.  Likely the rod was there first, and the deck
> was built over it.
> Breaker boxes, switched disconnects, panel boards and ground rods must
> be accessible for inspection and repair.  It is common for ground rod
> connections to get disturbed by ground shifting, hit by grounds keeping
> equipment, etc. and thus require the clamp to be tightened over time.
> The typical house or ham ground rod does little to improve your RF
> performance, as the inductance of the long lead between the shack ground
> bus and the electrical entry ground rod will often mean you have a
> quarter wave situation at the high bands, ie high impedance at one end
> where your rig connects.
> Better to put a buried halo ground around the house outside the
> foundation, and connect, (bond) both electrical grounds and the
> communications grounds, as well as ham radio ground to it.
> That way, you have provided a physically short path to earth from any
> place in the house where the shack might be.
> Be aware however, everything bonded together, with the case of a less
> than good conducting earth, that you could have a hit on an antenna mast
> or tower, bonded to the common bus. The whole of the bonded system will
> rise to a very high potential, and might conduct harmful currents into
> equipment bonded to everything else.  We had this happen at the club
> station:  tower was hit, current came in on shields of coax, (coax was
> INSIDE the tower), and continued into the shack where it went around the
> room on our bus bar, up into a VHF radio, and vaporized the circuit
> board negative power trace before arcing through the power supply to the
> AC third pin ground path back to the AC utility ground.
> The ground bus was L shaped around two sides of the room and on the
> short side went out to a metal water supply piping system.  Everything
> was bonded to it with wide flat conductors, thus low inductance.
> All AC outlets were bonded by the AC wiring (3 wire plus conduit).
> Sometimes it is just going to get you if equipment is left plugged in.
> Stuart Rohre
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