All of the ground rods that I have seen are 1/16 undersized in diameter. I
was not aware that these did not meet code. I have been buying 3/4 ground
rods from an electrical supply house because the 5/8 ones did not fit the
5/8 Polyphaser ground strap clamps that I use.
John KK9A
To: towertalk@contesting.com
Subject: Re: [TowerTalk] FW: Tower Grounds
From: Grant Saviers <grants2@pacbell.net>
Date: Tue, 17 Oct 2017 08:15:30 -0700
When I upgraded my tower grounds, I bought rods at a commercial electrical
supply house and Home Depot. The 5/8" rods looked a bit small and a
caliper showed them undersized. I then checked some 1/2" I had on the
shelf, and they were undersized also. I found this article
http://www.galvanelectrical.com/pdf/groundrodmarkingcompliance.pdf
I have never seen a "code compliant" stamped ground rod. Also, I have no
way to measure Cu plating thickness, but would assume it was cheated on as
well. Probably they all came from China where 1" = 19mm.
One thing I did learn in measuring the results was that #2 wire
contributed significantly to reducing the DC resistance of a leg (35' #2
plus 2x 8' x "5/8" rods). (some earlier rods were #8 connected). Since #2
is 0.258" diameter (mine is USA #2) and 5/8 rods were about 0.58" the
circumference ratio is 2.24. So 35' of #2 solid earth contact area is
about equal to 2x 8' x 5/8- rods. Of course buried 6" the field
distribution is a bit odd, but at DC it helped to get near to the Motorola
5 ohm target. Also, I'm confident the #2 copper will be there after the
copper flash on the rods is long gone.
Additional reasons to use a Ufer.
Grant KZ1W
_______________
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|