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[TowerTalk] Ufer Grounding System

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Subject: [TowerTalk] Ufer Grounding System
Date: Wed, 25 Feb 1998 08:24:41 -0800
If you get PolyPhaser's tutorial, "The 'Grounds' for Lightning 
and EMP Protection" you'll notice they show 2/0 pigtails coming
out of the rebar and connecting to the tower base and radial system
just as Dick describes. I was one of the two Poly engineers who assisted
73, Bob AA0CY
ex Senior Applications Engineer, PolyPhaser
now in process of moving to the Seattle area.
(Don't worry, there are enough contesters now
in northern Nevada [K7BV, K5RC, N7TR] so only
the RTTY'ers will suffer.)

Sent:  Wednesday, February 25, 1998 4:50 AM
Subject:  [TowerTalk] Ufer Grounding System

A few months ago on this reflector, Dick, W6OLD, published some comments
regarding the grounding approach he took for his tower and antenna system.
Recently, I asked him some questions about his installation.  His comments
were certainly of interest to me, and I thought they might also be beneficial
to the group:
73 - Phil, N6ZZ
>2.  You mentioned that you have 8 pigtails of 2/0 wire attached to the rebar.
>         A.  Are these just clamped to the rebar, like with Polyphaser's
>bronze transition clamps?

>3.  You seem to have paid a great deal of attention to the foundation part of
>your tower installation.  I noticed that Polyphaser mentions that their 1.5"
>strap has lower inductance than 2/0 cable.  That being the case,
>        A.  Why did you opt for the 2/0 cable rather than the strap?

Physical strength and durability.  The pigtails would have to withstand the
force of the concrete being poured in the hole and would be exposed to
human and natural elements where it came out of the concrete and was bonded
to the tower, itself.  The strap is nice, but it can be fairly easily
twisted and torn by rough treatment.  As soon as the pigtails cleared the
concrete at the trenches, I bonded them to the strap which was then
protected by being buried.

If you imagine the rebar cage, picture the top horizontal ring of rebar
about six inches below the surface of the concrete.  Now picture the second
horizontal ring about a foot below the first.  It was this second ring that
all the pigtails were bonded to so when they exited straight out of the
concrete, they exited about 18" below the ground, into the base of each
trench.  I also attached two more 2/0 pigtails to this "ground ring."

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