On Mon, 13 Sep 2010 09:40:00 -0400, Don Wilhelm wrote: >If we were discussing RF, then your single point ground connected to a >low impedance ground for RF would be correct - keep the path to RF >Ground the same distance for each piece of equipment. will achieve what >is needed for lightning protection.
I disagree with that concept as well. The notion that a separate wire is required for each piece of gear to a point that is often at a fair distance from a closely arranged collection of gear in a typical ham shack when that gear is already well bonded together does not make sense. How, for example, do we insure that each wire is the same length, follows the same or a similar path, and thus has the same inductance? There is NO CONFLICT between bonding all equipment chassis together by the shortest practical path, as I've outlined, and making one or more bonds between that equipment and the earth electrode system (ground rods). Indeed, both IEEE Standards on Grounding and most building codes either recommend or require multiple paths to ground for lightning protection. A large part of the thinking behind that is that the inductance is reduced by having multiple wires in parallel. As hams, we tend to think of our antennas as the only source of lightning ingress to our homes, but that is FAR from reality. It's like looking at the circus elephant through a tiny hole in the tent. EVERY CONDUCTOR that enters the house, and every conductor INSIDE the house, is a receiver for energy from lightning. That's why IEEE Standards and nearly all building codes call for ALL non-powered metal to be bonded together, and to one or more earth connections, and for all earth connections to be bonded togther. One other thought on this. In thinking about how all this fuzzy thinking about so-called single point grounding came about, one source of it might be equipment with a pin 1 problem. If, for example, the bonds to the equipment are improperly made to some point OTHER THAN THE CHASSIS, then yes, lightning current WOULD go through equipment if it was daisy-chained. But that's not a GROUNDING problem, it's an EQUIPMENT problem, and it's IMPROPER bonding. The good news is that I don't recall ever seeing ANTENNA connections in ham gear with pin 1 problems (except, perhaps, for an occasional RX antenna). It's only the audio and control wiring, and an occasional IF output. 73, Jim Brown K9YC ______________________________________________________________ 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
