I appreciate all the email on this subject.
Interestingly, when lightning rods were placed on barns all over this
country, I cannot recall any barn in our region ever catching on fire
because of a lightning strike. I am sure that it did happen in other
regions, particularly, in the Midwest/ The installation was to run a very
large conductor cable from the lightning rod to the ground. There were
generally two rods on either end of the roof. I would theorize that a
lightning strike should be directed to a ground rod placed a few feet from
the tower rather than to travel under the base of the tower as some have
suggested. I am going to ground the tower at the three legs with a copper
strap and then to a ground rod about 3 feet from the tower.
Also, the Empire State Building and other skyscrapers get struck many times
during a thunder storm and I wonder if anyone knows if the lightning travels
through the superstructure or through cables/straps to the base of the
building and through ground rods.
Thanks
Dave, W3ST
Publisher of the Collins Journal
Secretary to the Collins Radio Association
www.collinsra.com - the CRA Website
Now with PayPal
CRA Nets: 3805 Khz every Monday at 8 PM EST
and 14255 every Saturday at 12 Noon EST
----- Original Message -----
From: "Gary Schafer" <[EMAIL PROTECTED]>
To: "'Stevan A. White'" <[EMAIL PROTECTED]>; "'Discussion of AM Radio'"
<[email protected]>; <[EMAIL PROTECTED]>
Sent: Monday, June 12, 2006 10:10 PM
Subject: [Boatanchors] RE: [AMRadio] Tower Construction
Be careful when giving this advice.
A UFER ground is a good SUPLEMENTAL ground in a tower base but it should
not
be the only ground. A large area like a floor of a building provides more
surface for the lightning to dissipate. A tower concrete foundation may
not
be large enough by itself and there is the possibility of poor connections
inside so that the concrete crack from a lightning strike if it is the
only
ground connection. It is always recommended that ground rods be attached
to
each tower leg in addition.
73
Gary K4FMX
DO RUN THE GROUND THROUGH THE CONCRETE! Take a look at the information
on
this site first though. You may be glad you did.
http://www.scott-inc.com/html/ufer.htm
Best Regards,
Steve White, W5SAW
SW Commercial Electronics
-----Original Message-----
From: Ed Swynar [mailto:[EMAIL PROTECTED]
Sent: Saturday, June 10, 2006 2:16 PM
To: Discussion of AM Radio; [EMAIL PROTECTED]
Subject: Re: [AMRadio] Tower Construction
Hi Dave,
I have a 48' tall, tapered, self-supporting "Delhi"-brand tower --- 6
sections at 8' long each.
The prescribed / manufacturer's recommendation is to bolt a 3' straight
formed extention at the base of each leg (total of 3), & to "suspend"
these
(a temporary wooden "cradle" will do admirably, as the cement sets) in a
hole dug 4' square, & 4-1/2' deep --- the cement is to come but a few
inches
below the bottom legs of the actual tower section.
Oh yes --- the bottom 1' of the square hole is to be "belled" outward a
foot, or so.
The documentation says this is good for heights of up to 64', or
so...I've
never gone beyond 48', & have never, EVER had an ounce of trouble in the
two
locations that I've had my tower up.
BTW, the top of the tower as an old Cornell-Dubelier AR-44 rotator, & a
3-element Hy-Gain TH3 MkIII triband yagi...
Use "industrial"-grade coarse cement, & do NOT run any ground leads
through
the block itself!
~73~ Eddy VE3CUI - VE3XZ
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