[TowerTalk] Are "Ufer" grounding BEFORE pouring base cement?

[Scott Neader]

>For what its worth the 15 edition on the Antenna Handbook ( I need to buy a
>new one ) says " The bars are positioned so that they will not contact an
>metallic object in the base itself. This is done to minimize the possibility
>of a direct discharge path for lightning through the base. Should discharge
>occur, the concrete base would likely explode and bring about the collapse
>of the tower."

Likely?  Really?  OK, if it's likely, then surely it must have happened
ONCE by now?  In 1995, the question was asked to the CQ-CONTEST mailing
list if ANYONE could recall ANY tower (ham, CB, VHF/UHF, radio, TV,
microwave, whatever) having a base explode due to a lightning hit.  No such
evidence was found (although one guy seemed to remember that perhaps one
ham has mentioned... well, you get the picture).  You can look at an
archive of this discussion (which went off topic several times) at
http://www.QTH.com/KA9FOX/mail_summaries.shtml

I am by no means an expert on this subject (quite the opposite), but I have
been led to believe that the folks at PolyPhaser know a lot about
grounding, and I suspect they would not publish a book containing clear
instructions to use a Ufer in addition to your ground radial/rod system if
there were ANY possibility that this could potentially damage a tower
system or cause an exploding base.

For the cost of some copper to tie the tower to the cage and the cage to my
future ground system, I see some benefits and I don't see any negatives.
Yes, some have a 'theory' about exploding bases, but where is the proof?
Surely after the CQ magazine article back in 1992, plus all the information
from PolyPhaser, plus remember that Ufer began his work on this subject
during WORLD WAR II, enough Ufer installations have taken place that we'd
have heard SOMETHING about exploding bases or other side effects of using a
Ufer ground???  According to PolyPhaser, they are only aware of ONE site
that had cracks that COULD have been lightning induced (and who's to say
that it wouldn't have happened had the Ufer not been installed?).

Anyone want to come forward and tell us about a tower or two that had a
Ufer ground installed in addition to a 'normal' ground rod/radial system,
and the tower was hit by lightning and the base cracked or exploded?

FYI, when this subject quiets down, I'll compile/summarize this info and
store it on my site for future generations. :-)

73 Scott KA9FOX


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