No confusion at all, Jim. I know the difference between the two. His reinforcing steel inside his driveway is probably way far out of the realm of Ufer grounds, due to it being small gage conductors. Aside from the great difficulty of boring into the concrete and adequately bonding to those wires, I wouldn't try this anyway out of concern that the current density during a major lightning hit might be sufficient to produce widespread cracking of the concrete.
Now I'll have to go re-read and brush up on Ufer grounds, but as I remember, his driveway setup would be woefully inadequate for the possible current levels involved in the event of a direct lightning strike. Personally, I wouldn't go there. A concrete drive would be a little pricey to replace, especially considering the relatively small prospective gain in HF ground quality he might see by connecting his radial field to it. I'd much rather connect *over* that drive using strategically sawed grooves and lightly concreting in a few wires at the surface in a few places- this assuming he has somewhere to go on the far side of the drive with those wires anyway. I know a ham who thought his well pipe might make a dandy addition to his ground radial system. He connected it, and eventually had to replace a 600 dollar well pump after a strong lightning hit on his property. This driveway question reminds me of that. Properly designed Ufer grounds, fine- but I sure don't want to invite lightning hits to dissipate through anything concrete on my property. My two cents (two dollars, adjusted for inflation...) David K3KY There is considerable confusion here with respect to radial systems for antennas and an earth connection for lightning protection. They are VERY different, and both are important. Properly bonded conductors buried in concrete ARE acceptable as a ground for lightning protection -- it's called a Ufer ground, after Herbert Ufer who developed the concept, and it's now recognized in the National Electric Code. A Ufer ground works because 1) concrete is conductive and 2) there is a large surface area in contact with the earth. The downside is that the earth it makes contact with is near the surface. Like ALL earth electrodes, it must be bonded to all other grounds in your home -- power system, Telco, CATV, your shack, and all driven rods. I think Bob is on a pretty good track with his design. For more ideas, see http://k9yc.com/160MPacificon.pdf 73, Jim K9YC _________________ Topband Reflector Archives - http://www.contesting.com/_topband
