As an “expert” in lightning, even publishing a paper some 40 years ago with research and study before and after, it all goes back to Ben Franklin.
1. He invents the lightning rod to attract or “catch” the strike, thus protecting the structure, further engineered for the 45 degree cone of protection and positive vs. negative origination of the least resistant path. 2. He notes, “behold, the corona shows discharge of the charges, hence dissipating the voltage potential and avoiding the strike.” I found then, as now, that a couple of companies guarantee your protected facility will not be struck by lightning, or if so, no damage will be incurred. This has been formalized into an “open source” like standard with a 3 prong approach, used in virtually all hardened installations. 1. The first leg is to eliminate voltage potential by tying all “wires” to a single point, both inside and outside a sole and single entry point to the facility. Inside, you see a halo of grounding buss for all ground points. Outside, a single low impedance ground buss with a sole and single lead of sufficient size entering the protected facility. For the discussion of a low impedance lightning ground, the electrical green ground, case/chassis/building structure grounds, water pipes, telephone and all other items that are capable of carrying a lightning charge. Not unlike how a Faraday cage would be constructed. The lightning strike serves to equalize the difference in sky vs. earth ground potentials. This dissipation moves out from the actual strike point in the earth in waves, as a stone in a pond, with hundreds of thousands of volt potential difference short distances between the “waves”. This is why while standing, it can go up on leg and down the other. To eliminate this potential, with a single point of contact again, when you feel the hair on the back of your head raise, you drop to the ground with your hands on your knees, minimizing the physical distance and magnitude of any voltage potential between points of the ground. When gas, electrical service, cable all enter the facility at different points, all need to be bonded and connected together at proper distances and cadwelled. 2. The next leg of the stool is to dissipate the charges pre-strike with sharp point coronas. Multiple sharp points at the highest elevation, often in an umbrella like skeleton, often massive. Porcupine like bundles of 50, 12 inch or so stainless spikes are available for hams that I have used with success. In Houston, the charts show some 2-4 strikes predicted for well grounded towers of a hundred feet above average terrain and my personal experience has been about a strike every 2 years. 3. Once the strike has occurred despite efforts, you ground the piss out of it to drain the charge to a low impedance ground. Ground rods are arranged in a line, a triangle or even around the entire structure at a spacing distance equal to the length of the rod. An important issue in short cut grounding is to fail to cadweld these bond connections. A clamp corrodes, especially a hose clamp, gets loosened and changes impedance – not good. 4. Lastly, when EMP type protection is added, or for a more robust lightning design, arrestors are added to coax center conductors for example, to give the EMP or lightning an alternative path to ground instead of through the connected, protected equipment. Spark gap, gas discharge and others designed for the rise time of the voltage spike you are worried about. I have used these with success: https://www.dxengineering.com/search/department/grounding-and-lightning-protection/product-line/polyphaser-coaxial-lightning-protectors?autoview=SKU&sortby=Default&sortorder=Ascending I believe you will find these concepts in current state-of-the-art discussions while unplugging the coax just might lead to things like ball lightning phenomes. End of rant, back to lurking. 73, KB5F orin ________________________________ From: BVARC <[email protected]> on behalf of Robert Polinski via BVARC <[email protected]> Sent: Wednesday, April 8, 2020 4:50 PM To: 'BRAZOS VALLEY AMATEUR RADIO CLUB' <[email protected]> Cc: Robert Polinski <[email protected]> Subject: Re: [BVARC] Antenna Mounting Options The National Electrical Code (NEC) requires any supplemental grounding rods (and antenna or station ground rods meet this category) to be bonded together with #6 copper wire. Should be as short as possible with no sharp bends. If run through metallic conduit, it must be bonded to the pipe at both ends. (otherwise the pipe will act like a choke ) A #12 is better than nothing & will at least prevent shock potential between grounds but would not help alot with a close lightning strike. All equipment should have good lightning arresters (polyphaser 1 brand, DX eng another) on the antenna, all well grounded and bonded. Hams will pay $3500-4000 for a radio and not want to spend $100 to protect it. I know, you all disconnect your radios from power & ant EVERY time you are not using them, no worries here, as you drive home from work, and see that dark cloud forming over were you live!! LOL Robert KD5YVQ From: BVARC <[email protected]> On Behalf Of Will Gray via BVARC Sent: Wednesday, April 08, 2020 3:51 PM To: BRAZOS VALLEY AMATEUR RADIO CLUB <[email protected]> Cc: Will Gray <[email protected]> Subject: Re: [BVARC] Antenna Mounting Options Submarine, North Sea, big helo , rain storm: nasty setup, the kind of event that generate great sea stories (they are all true, though change a bit when told over the years). Likely the static charge from the helo rotes caused the strike. I would go for #4 or #6 solid copper wire for the ground circuit. Tie your ground to the utility inlet ground, water pipes and gas pipes. depending on the setup, might want to add a couple more of those 8' ground rods. Still there is no guarantee but it improves the odds. Will, KB7QL On Wed, Apr 8, 2020 at 3:36 PM Ron Bosch via BVARC <[email protected]<mailto:[email protected]>> wrote: Will, et al, To agree with you in a backhand kind of way, I have, in fact, seen lightning hit a submarine while at sea in a rain storm in the North Atlantic, although the lightning in question came off of a line hanging from a Sea Stallion, and was VERY Impressive to a 20 year old ELT whose job it was to make sure the deck was radiologically clear prior to a med evac. To bring it back to topic, though... Having just gotten back into HAM radio after a 10 year absence, I have recently acquired some new and expensive toys. The "current" grounding set up is a 12 GA wire run from my station to the ground rod put in as part of the repaneling of my electrical into the house. The ground rod in question is an ~8 foot copper rod driven into the ground with about 6 inches showing above ground level. I bonded the 12 GA wire to the rod with a hose clamp. Do you all think that sufficient to protect my brand new ID-4100 and IC-7100? Ron KE4DRF Judging by personal experience, the next public health crisis after COVID 19 is likely to be cirrhosis. Ron Bosch "..any man who may be asked what he did .. to make his life worthwhile, I think can respond with a good deal of pride and satisfaction" 'I served in the United States Navy." John F. Kennedy When I was young and bold and strong, Oh, right was right, and wrong was wrong! My plume on high, my flag unfurled, I rode away to right the world. ‘Come out, you dogs, and fight!’ said I, And wept there was but once to die. But I am old; and good and bad Are woven in a crazy plaid. Dorothy Parker "The best lack all conviction, while the worst are full of passionate intensity" Wm Butler Yeats "Believing with you that religion is a matter which lies solely between man and his God, that he owes account to none other for his faith or his worship, that the legislative powers of government reach actions only, and not opinions, I contemplate with sovereign reverence that act of the whole American people which declared that their legislature should "make no law respecting an establishment of religion, or prohibiting the free exercise thereof", thus building a wall of separation between church and State." Thomas Jefferson "Fix reason firmly in her seat, and call to her tribunal every fact, every opinion. Question with boldness even the existence of a god; because, if there be one, he must more approve the homage of reason, than that of blindfolded fear." Thomas Jefferson in a letter to Peter Carr A Government founded upon justice, and recognizing the equal rights of all men; claiming no higher authority for existence, or sanction for its laws, than nature, reason, and the regularly ascertained will of the people; steadily refusing to put its sword and purse in the service of any religious creed or family, is a standing offense to most of the Governments of the world, and to some narrow and bigoted people among ourselves. Frederick Douglass On Wed, Apr 8, 2020 at 11:53 AM Will Gray via BVARC <[email protected]<mailto:[email protected]>> wrote: Lightning is interesting. The strike begins when the electrons that have been scrubbed from the air by rain or snow are deposited on the ground (generally). A negative charge builds where the earth acts like the plate of a capacitor. With no other path the charge gets great enough to find the path of least resistance back to the atmosphere overhead or nearby from where the electrons were scrubbed by failing rain. If the area is well grounded, the electrons are dissipated in the the earth, if insulated (why lightning strikes concrete runways) the charge builds. If your house, ground, trees, or anything is insulated allowing the charge to build, the strike will occur when the charge is great enough. In my years at sea in he Navy, I never saw a lightning strike hit the surface of the water or the ship, no matter how heavy the rain. The salt water as a conductor dissipated the charge. Aircraft flying in rain build up a charge and may be struck, damaging them with burn marks and even scoring bearings in the engines. Aircraft have static wicks to bleed off the charge just as trucks have straps to bleed off the charge so the 7,000 gallons of gasoline in a tanker truck doesn't go up in flames from a lightning strike or lesser static discharge. Will Gray, KB&QL On Wed, Apr 8, 2020 at 11:38 AM Robert Polinski via BVARC <[email protected]<mailto:[email protected]>> wrote: Much what is said is true, but I will add a few points. Forty some years ago I worked for a 2 way radio co. We had the Yellow Cab contract. I was at Yellow Cab on Hays street in north Houston. I was replacing 2 radios in the radio shack at the base of the 450ft tower that had been removed and taken to the shop for repair. As I got setup to replace the radios in the rack, there were 4 radios & 4 standby radios in the rack. They used 4 VHF channels at that time. There was a thunderstorm approaching outside. The radio shack was just a small 8x 12 building a the tower base. The radios were DC remote controlled from the dispatch office located 100 ft away. I waited for the storm to pass before installing the repaired radios, as I did not want the touch the rack a long as the storm was near. As I sat on the floor of the shack looking out the door, it was raining real hard. I then saw lightning strike the power lines behind the mechanic shop about 300ft away. It blew a AC receptacle on the wall behind me off the wall. Damaged 2 of the 4 radio power supplies, 1 DC remote. I had disconnected all the standby equipment before the storm to facilitate the installation of the replacement radios. To make a long story short (LOL) The lightning hit the power line 300ft away from a 450ft tower. No lightning came down the tower. So just being high in the air, does not necessarily make it a lightning rod. What is important is bonding everything together. If all equipment in your shack is at the same potential, the lightning current will not have anywhere to flow. I can charge the case of your K3 with 10,000v but if there is no current flow no damage will occur. If lightning hits the power line and the ground rod at your shack is a better path than the AC ground at your meter the current will travel thru your rig to get to the rod. If you bond the shack/antenna ground with the AC ground with a #6 wire. Since both are at the same potential, there will be no current flow & no damage. ( this bonding is required by the NEC) See Mike Holt on you tube to understand this. Robert KD5YVQ From: BVARC <[email protected]<mailto:[email protected]>> On Behalf Of Eddie Runner via BVARC Sent: Wednesday, April 08, 2020 9:53 AM To: Mark Brantana via BVARC <[email protected]<mailto:[email protected]>> Cc: Eddie Runner <[email protected]<mailto:[email protected]>> Subject: Re: [BVARC] Antenna Mounting Options Mark, it is true, lightning does what it wants to do. I have had outside antennas of all types including towers , long wires, dipoles, cb antennas, shortwave, Ham of all kinds, over the past 50 years, I have had houses with ground rods and houses without ground rods and even when I had ground rods some antennas would sometimes not be grounded... (one house I had 19 antennas up at one time).. I have a rule, if there is a threat of lightning, I AM NOT GONNA TOUCH THAT COAX.. So that means I NEVER disconnect my coax when a storm comes.. NEVER...NEVER... As far as I can remember I have never had lightning damage on any radio gear.. Back in the 80s there was some speculation that lightning may have come in through the phone line and destroyed 2 modems ( I used to run BBS's).. I have seen a few times where lightning hit TOWERS or POWER PANELS on homes, some were hams and some were just people with no antennas... I have seen gear supposedly hit by lightning.. Maybe some was, maybe some just blew the finals cause the guy forgot to hook up the coax he unhooked the last time he heard thunder.. ha ha But even all the times we know about, it is still fairly unlikely.. and if the lightnng has your name on it.. ??? Good luck.. it is all VOODDOO..ha ha Eddie (NU5K) On Wednesday, April 8, 2020, 06:16:29 AM CDT, Mark Brantana via BVARC <[email protected]<mailto:[email protected]>> wrote: Since folks are hunkered down anyways, here is a problem. I am improving my emergency radio capability by adding a 2-m radio to my home office. Who knows where this thing is going, and I think this is a good time to prepare. I would like your thoughts or experience with the following. I am looking to mount a 2-m antenna on my roof. Currently I have a TV antenna attached with a j-pole just below the chimney output. I have a single-story house. My plan has been to extend the j-pole about 4 ft higher to get better TV reception, and mount the antenna just above it. I do have to watch out for offending the HOA. My property has power lines running parallel with the back of the house, and these power lines are about 35 feet high and 35 feet laterally away from the chimney. I am concerned about a couple of things: 1. Some day I may want to start a fire in the fireplace, and I do not want the heat to get to the antennas. This is why I have the TV antenna mounted below the top of the chimney. 2. I would like to avoid arching or lightning strikes, though I think it is quite common for most of us to have power lines around to contend with. Two thoughts here: * Of course, I will ground it all. * I wonder if the power lines might protect the lower antennas since lightning may hit them first. I mention this since the first thought was that the power lines might add to the lightning risk, not detract. * That said, lightning does what it wants, and even a nearby lightning strike, as opposed to a direct strike, will do significant damage. On that last point, I will share a short story. When in Louisiana many years ago, we got into a discussion about how lightning had destroyed a lot of equipment in a member’s shack. This included, as I recall, about 3-5 computers, and about as many radios. This was all sitting on a metal table. Due to the lightning storm, the Ham had disconnected all of the antennas. Lightning hit his tower and made the 2” jump to the table. The rest was history. But, that was not the story I wanted to tell. That was the discussion we were having. Another Ham broke in and told us that he had a tower at one end of his house which was operational, and he had just that day mounted a short marine antenna at the other end of the house on his chimney. It was a dark and stormy night the previous evening, and the lightning passed the tower to hit the yet unconnected marine antenna. So, lightning does not follow the rules. OK, so I diverged. I really would like to know what experience and advice you can offer me on my project. The power lines make me nervous, and I really wish my best mounting option were not in the heat zone of the chimney. Mark N5PRD ________________________________________________ Brazos Valley Amateur Radio Club BVARC mailing list [email protected]<mailto:[email protected]> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org ________________________________________________ Brazos Valley Amateur Radio Club BVARC mailing list [email protected]<mailto:[email protected]> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org -- 431 Forest Circle Ruston, LA 71270-2642 H:318-251-2219 C:318-265-2976 (text) [email protected]<mailto:[email protected]> ________________________________________________ Brazos Valley Amateur Radio Club BVARC mailing list [email protected]<mailto:[email protected]> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org ________________________________________________ Brazos Valley Amateur Radio Club BVARC mailing list [email protected]<mailto:[email protected]> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org -- 431 Forest Circle Ruston, LA 71270-2642 H:318-251-2219 C:318-265-2976 (text) [email protected]<mailto:[email protected]>
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