Hi all,
Here is an article that I published in our club news letter in 2003. You
may find it interesting as it explains the origin of the "Ufer" ground
system.
73, Tony VE3DWI.
*********************
An Ufer what???
Have you ever heard the expression “Ufer ground system”? I have on
occasion, and wondered what it meant too. Finally curiosity got a hold of
me and I had to know. After some research on the internet I came upon some
articles and thought to share the information I had garnished. What follows
is an excerpt of an internet article by Chris Scott & associates about this
subject.
During World War II, a retired Vice President of Underwriters Laboratories,
Herbert G. Ufer, developed it (the Ufer ground system) for the U.S. Army.
Igloo shaped bomb storage vaults were being built, and possible static and
lightning induced detonation problems were of concern. Ground conductivity
was poor, and to be effective enough, ground rods would have to be driven
several hundred feet. After much research and testing Mr. Ufer advised the
Army to make connection to the steel bar that would internally reinforce the
concrete foundation. He had determined that concrete was more conductive
than all but the best soil, and that this improved semi-conducting
characteristic would enhance surface area contact with the surrounding soil.
The wire ties normally used would be extra secure, and attention would be
given to bonding or welding the lattice-type network together. The Army
adopted the idea, and built the vaults as specified. After construction
ground resistance tests were made. No measurement exceeded five Ohms. This
value was considered extremely low for the local soil conductivity. Later
tests confirmed stability. Mr. Ufer went on to develop the concept of
concrete encased grounding electrodes. Many of his findings are detailed in
IEEE Transaction paper #63-1505. His system has since been used by the
military, utility companies, Lake Tahoe lifts, and industry throughout the
country.
Tony VE3DWI.
******************************
----- Original Message -----
From: "denton sprague" <denton@oregontrail.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Monday, August 12, 2013 9:20 AM
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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