Jim's slides give great examples and the msg or either keeping all connections at the same potential or completely isolated is all very good advice.
Having dealt with this my entire life in industry though, there is one more thing to add. Lightning strikes are always matters of probability. If you get a DIRECT strike, no bonding etc. is sure to save you with the energy released in such a hit. We are talking possibly hundreds (even thousands) of amps of current and very high voltages. On TWO occasions I have witnessed those Square-D Whole House line protectors blow clear out of the breaker box in a direct strike into a smoldering pile on the floor. My take-away from that is the only marginally safe place for my expensive radios was as disconnected and in the shipping boxed in the (faraday) closet in the basement during a storm (just like an airplane). Dr. William J. Schmidt email: b...@wjschmidt.com -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Jim Brown Sent: Monday, July 31, 2023 5:25 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] A dumb question about lightning On 7/31/2023 2:14 PM, jerry wrote: > Interesting. Suppose the service entrance is at one end of the house, > and the ham shack at the other end? I don't think it's physically > possible to provide a low inductance path that's 60 feet long, is it? I've posted a link to my tutorial, which covers this, but which folks who need to know what's in it haven't bothered to read. Fred is absolutely correct, BY LAW, all grounds in a premises MUST be bonded together. In his ARRL book on the topic, to which I contributed, Ward Silver, N0AX, recommends a perimeter ground ring, connecting multiple driven rods. A full perimeter ring wasn't practical for the building that houses my shack, so I did a half perimeter ring from the sub-panel for the building to the shack on the other side of the building. Jerry is entirely correct -- indeed, the rule of thumb for bonding between a tower and the building(s) where there's no mains power at the tower is to NOT bond if the tower is more than 100 ft from grounds for the building (and some references suggest 60 ft). The whole point of bonding all the grounds is so that in the event of a strike, the entire premises rises as closely as practical to the same potential, minimizing the potential difference between grounded equipment and surfaces. Re-posting the link. http://k9yc.com/GroundingAndAudio.pdf And it's NOT mainly about audio. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to b...@wjschmidt.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
