You assume wrong. :) Concrete is a conductor, and metal that makes contact with it forms a Ufer ground (that is, a ground electrode). By virtue of having a lot of surface area in contact with the earth, the Ufer ground can have a fairly low impedance to earth. The tower is bonded to that copper and to ground rods that surround the tower. Thus, the total impedance to earth is the parallel combination of all of those electrodes.
Again, the fundamental principal is that all grounds MUST be bonded together for lightning safety. In the event of a lightning hit, the potential of all rise together, so it is much less likely that something bad will happen in the building. We say "less likely" because those bonding conductors have resistance and inductance, so the potential difference won't be zero, but it will be lower than if there were no bonding. 73, Jim Brown K9YC --Original Message Text--- From: Ken Kopp Date: Tue, 1 Sep 2009 06:47:39 -0000 Hi Jim, I assume the straps in the concrete were an experiment to measure the resistance of concrete and -not- intended to be for lightning grounding. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
