Is it really necessary…..? https://newenglandgmrs.com/wp-content/uploads/filr/1850/STATION-GROUNDING.pdf
So funny story about grounding. I have a ground rod that my radio ties to as well as my feedline switch. It is probably 15 feet from the ground rod for the subpanel of the building my shack is in. They are not bonded at this time. I was having an issue with my IC-718 where it would receive fine but any time I tried to transmit anything over a couple watts it would die on me. I fiddled around with the power supply and found no issues there(I've had bad powerpole connections there before). I finally discovered that the negative side wire of the power connector at the radio had pulled completely out. Tracing it out, the only way my radio could have been working to receive was that it was pulling it's negative from the ground wire I had hooked up. The only way it was completing the circuit back to my power supply had to have been through the damp ground, through the other ground rod, and back through the ground wiring of my building. The ground itself obviously allowed just enough current to power on the radio and listen but was not enough trying to transmit. I promptly fixed the power connector and I'd venture to say if I had the two rods bonded, I may not have found the issue because it probably would have transmitted fine and just pulled a lot of current through my ground circuit.(I don't think it's on a GFCI)
Hi Frank, your calculations are not useful if you want to build up a fully LPS by your own. Following links will show you a good start into these topic. The first link is in english, the second in german. Both got different informations about a how to and what is to observe. Be careful. https://www.lightning.gg/wp-content/uploads/2021/09/z.Furse-Guide_3rd-Edition.pdf https://de.wikipedia.org/wiki/Blitzschutz
If you are that serious about grounding, start here. Way overkill for what you actually need, but it's a great resource. https://joshaven.com/resources/grou...DS_AND_GUIDELINES_FOR_COMMUNICATION_SITES.pdf
If we would have used only one ground rod to ground a station and tower, there would have been a lot of communication sites off the air during a storm. The whole object here is to bond everything (tower, coax, radio, electrical system, generator, etc.) together. During a lightning event, all those item will rise and fall equally to ground. Reference the guide mentioned above (Motorola R56) . In some cases it's overkill but will explain this theory. I have a 45' tower and multiple antennas around the property all bonded to the same ground system which includes my radio equipment. All in place for 10 years with no issues. Tom Kravcar Co-author of Motorola R56 manual
HIGHLY recommended: ARRL's Grounding and Bonding for the Amateur. Easy to understand and accurate. R56 is fantastic but a bit much for the average ham to swallow. -Gary NA6O
Quote from W5CJA "I'm confused...does your home not have a common ground located somewhere near the point of entry?" My house was built in 1959, and it used(and still does) use the cold water pipe where it comes in to the house. A 6 gauge copper wire was clamped on the street side of the meter and that ran to the breaker box. I think many homes were grounded in this manner and that was the only means of grounding we had. OK fast forward to 2003, we did a major remodel on the house. I added a #2 ground ring at the base of the foundation (28' perimeter) and spaced 6, 10' ground rods around that, replaced the #6 wire to the street water pipe with a #4(we upgraded to 200amp) and of course bonded the ground ring I installed to the electrical ground in accordance with article 250 NEC. All of the cables for ham radio, TV antenna, dish, etc are protected and connected to the grounding system. Also for every antenna mast on my roof I ran a #8 wire to a ground rod in a straight as possible path and the ground rods are all bonded together with #6 wire and bonded back to the main electrical ground. Keep in mind that many municipalities are using plastic water pipe and many new homes use pex, so the NEC has amended grounding requirements accordingly(IE requiring two ground rods in some situations, also UFER grounding which works very well) Grounding is important, especially with all of the modern computer and electronically controlled devices a typical household has in this day and age. When in doubt, article 250 of the NEC is a very good reference, and it keeps growing all the time.
The only purpose of ground rods is to provide a safety ground to ensure your GFCI's will trip and to provide some safety in case of a lightning strike. It will most certainly NOT provide you with an RF ground, unless you place your rig directly on top of the ground rod. And even then it won't be a good RF ground. So all these ground rods are just a waste of money and time.
Grounding..... what a complex subject. I know there is a quite a difference between electrical service ground, surge dissipation ground, and RF ground. I'm in the golf course construction and controls maintenance business. We've got jobs with 100's of thousands of feet of control wire in the ground. Lightning is induced on our wiring like nobody's business. I can only speak for surge dissipation, but we through the earth ground resistance numbers out a long time ago (for the most part). Instead, our own research and long term practical feedback tells us that a ground plate, coupled with a ground rod is sufficient for surge suppression, even here in Florida where storms abound each summer. Rods are 8 foot copper plated steel. Plates are .050 thick, 8inch by 8 feet long, and placed 8 feet from the rod. Neither is within 8 feet of existing buried wiring, and the plate should be perpendicular to the wiring. Rods driven (not dug, jeeze) to just below grade, in order to be accessible. Plates are 30 inches deep, between twin beds of GEM (sort of like black carbon filled portland cement). Plates are bonded to rods with Cadweld connections, and the wiring is #8AWG. In our equipment, we use - in the following input order - low amperage fuses, then gas pills to ground, then inductors in series, then MOVs and avalanche diodes in parallel, both to ground. The idea of the fuses is not protection, but for disconnection if the surge is sufficient to exceed the current capability of the gas pill. In other words, as the pill is dumping, the fuse is toasting, maybe opening eventually <--- all that taking place in the several blinks of an eye a lighting strike lasts. That has worked well. In cases where the plate cannot be used, we do seek the "25 ohms", as measured with a three point earth ground tester, at 200hz. Remember, the "resistance" of the rod is not DC, but more akin to AC, so its actually impedance. Lightning is rapid pulse DC. I've been hit three times in my life, the last being able to actually feel the pulsation. That's a long story. Also found that PolyPhaser arresters are totally useless for a direct strike. Our RF devices use a fiberglass vertical antenna at 60 feet elevation. Lightning will blow the fiberglass apart like Elmer Fudd's shotgun. I've never seen the coax damaged (LMR-400), nor the fittings. And, we do lose transmitters, sadly. However, the close strike protection of the PolyPhaser has not panned out for us, as neither unprotected or protected antenna systems will lose a transmitter, except for a direct strike (which the PolyPhases doesn't protect).
Precisely. I use the same principal. But 10 feet is too close. Usual installations are at least 2 rods at 20 feet apart bonded with an unbroken conductor cadwelded or clamped depending on municipalities for split phase entrance. 3 phase installations and line towers usually have a ground resistance test performed. Same with many commercial transmitter antennas. While this test is not generally mandatory, from an rf engineers prospective knowing the soil resistance and conductivity factor allows for more precise calculation of the signals radiation pattern and field strength. Sure regional conductivity information can be found by searching the web. But its only an average estimate based on limited sampling. But who knows if the sampling was taken on a hilltop or by a lake?
The biggest thing with grounding for rf is avoiding a ground loop like a plague. My shack is on an isolated circuit from the rest of the house because it has its own panel and ground rod. ( that rod is bonded to the main rods) But in most homes, unless its built strictly by code odds are there are loops in the ground circuits. I know ive found quite a few while troubleshooting clients homes for interference issues.
Note: There is a comprehensive list of excellent resources and references for grounding right here on QRZ, with some comments. It’s the very first post in the Antennas, Feedlines, Grounding and Towers forum. https://forums.qrz.com/index.php?threads/resources-for-antenna-and-station-grounding.756419/
