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
|