The significant requirement is that the rebar sections are bonded together
using using an exothermic process (welded). If the rebar (cage in tower
base) is just tied together (with wire) there may be enough resistance
between rebar sections when dissipating a lightning strike to cause heating
and bursting of concrete. If you do NOT know if the rebar is welded you may
want to reconsider your grounding options.
My previous work place used a Ufer ground mat (basement floor rebar of all
buildings of the complex) bonded to building steel (and pilings) with copper
grounding bars bonded to them. An external ground ring with ground rods was
bonded to each vertical building steel member, with air terminals (on each
building roof) bonded to building steel. Copper grounding bars in 14th story
equipment room were connected to the ground mat with a 250 foot run of a
pair of 400 MCM cables. The electrical service neutral and mechanical ground
were also referenced to the ground mat. When you have radio antennas at
1027 feet AMSL, (197 feet AGL) and main frame computers in the same
complex, you don't want a strike to take everything off line.
YMMV
73 ES DX,
Gary -- AB9M
-----Original Message-----
From: denton sprague
Sent: Monday, August 12, 2013 8:20 AM
To: Discussion of Ten-Tec Equipment
Subject: [TenTec] ufer ground?
I know this is kinda beating a dead horse to death, but ran across this
today….
http://www.comm-omni.com/polyweb/ufertower.htm
first time I have ever heard of a ufer ground….a recent post by KI6CFW on
eham also says this…
A ufer is a length of rebar (minimum of 20-25' or so long) embedded in the
building's concrete footer. One end of the rebar is bent up and extends out
from the concrete (usually near the electric service panel). The ground
from the electric service panel is attached to the piece of rebar.
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