Here is how to correctly protect against lightning

Discussion in 'General Technical Questions and Answers' started by AI3V, Nov 6, 2019.

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  1. KF5LJW

    KF5LJW Ham Member QRZ Page

    Good stuff Glen, you and I have parallel career paths. Your concept of SPG is correct. The only way to have all the cables at 0-volt potential is all are bonded together as close together as possible outside as NFPA/NEC requires to form a Ground Plane. Now allow me to bring back memories of the PANI Ground Buss. Remember them? I bet you do. This is the best way to implement a True SPG or as close as possible.

    Those letters PANI are an acronym for Producers, Absorbers, Non Producers, and Isolated. It would be a ground bar literately sectioned off in 4 quadrants from left to right and the letters with lines denoting the section. This tells you how to land ground conductors. Start with the Absorbers which are your Ground Electrodes sources you want to sink fault current to. So everything you have as an electrode goes in the A Section in the middle of the Buss Bar.

    Next up is the P or Producer section on one side of the bar all by its lonesome self. That is where you put all circuit wires that can Produce a Surge event. That would be things like Surge Arrestor Ground Points. coax cable shields, Telco surge protector, AC Ground Bus, CATV Shields, Coax ADU, or anything that can produce an surge event.

    So we have Producers and Absorbers segregated occupying half the Ground Bar. That is the section of Ground Bar where outside currents can flow between each other. A Producer looking for a place to go and see the Absorber to sink the current to EARTH below. That leave you half of the Ground Bar forming an Equipotential Ground Plane free of current and voltage. I am also certain you know an Equipotential Ground Plane has no resistance or voltage between any 2 points on the Plane. The Equipotential Ground Plane is where AC and RF merge together making it SPG as good as you can make it.

    Now go look at the drawings I made in a few threads. Shows you that same method of madness PANI concept employs. Just simple logical solutions, proven to work, documented, and used for decades. It works and works real good. Its the best protection you can create short of going underground or cement vault.
     
    Last edited: Nov 8, 2019
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  2. KF5LJW

    KF5LJW Ham Member QRZ Page

    MW is even a bit easier to deal with because there is no center conductor to deal with thus no surge protection required. Just properly bonded along the way and one last time after going inside to top of rack wave guild coupler and pressure window.
     
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  3. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Thank you, I get it and I think that will help clear up some of the confusion and argument in the thread.

    To restate, the single point ground is not about how many ground rods there are, as it might seem at first glance. It’s about creating a single ground potential reference for equipment in the building (or wherever the demarcation for the defining the SPG is made).
     
    Last edited: Nov 8, 2019
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  4. KF5LJW

    KF5LJW Ham Member QRZ Page

    You got it, and correct me if I am wrong, but I think you are a Sparky? If so you know I speak code and everything I have said complies and exceeds NEC minimum requirements.

    If you are a Sparky then you know without a doubt in your mind the NEC only allows the neutral circuit to be bonded once at the Service Entrance. Exact same SPG principle being employed. If you bonded the neutral twice anywhere down stream to Ground again would put ground conductors in a parallel Ground Loop and thus normal load current would flow on ground conductors causing voltage difference along it path which is pure noise and a safety threat. You know better than to allow current get on ground conductors as a Sparky. You might not know exactly why, and if you did not know now and understand.

    I know we have quite few Sparkies here on the forum I see over on Mike Code Forum and even a couple of RF Engineers who have chimed in and agreed with their 2-cents worth.

    Here is case in point. How many of you think Ground clears an AC fault in your house. I mean you think dirt actually plays a role? If you do, then you are dead wrong earth has no part and none of the ground conductors even need to be bonded to ground in order to work properly and facilitate quick operation of fuse and breakers. Only thing ground does once inside, an AC circuit is a 0-volt reference point. No fault current flows through dirt, NEC forbids it. Every micro amp flows on the copper wires and never touch earth.
     
    Last edited: Nov 9, 2019
  5. AI3V

    AI3V Ham Member QRZ Page

    Short answer, you wasted time and money pounding rods into the ground, and buying and installing a "host of lightning arrestors"

    And you can't find your service ground, and the fellow you called out (I hope you didn't give him any money...) Couldn't find it either.

    Did he INSTALL the required ground rod?

    Did YOU?

    And the book I linked to explains in detail why you are relying on pure dumb luck for lightning protection.

    I'm sorry, but there just isn't any way to sugar coat it.

    Rege
     
  6. AI3V

    AI3V Ham Member QRZ Page

    Amd when the big spark hits," the top of the rack"is thousands, tens of thousands of volts above ground.

    And all the wires, and the rack itself are at some other potential.

    It was time to upgrade that equipment anyway....

    Rege
     
  7. AI3V

    AI3V Ham Member QRZ Page

    What you are omitting ate the spark gaps (surge supressors) where the "hot" and "neutral" ac power wires, and any data or control wires are attatched to the strike plate- what you call a "adu"

    Of course the breakdown voltages of the spark gaps MUST be less than the voltage that will damage the circuits they are attatched to.

    And #6awg may or may not be heavy enough, nec notwithstanding.

    .......

    One other thing, the steel superstructure of a modern building works much more as a "Faraday cage" during a lightning event, you keep ignoring the tremendous MAGNETIC field that happens right with the electric current.

    Why?

    Perhaps you have seen the "arc chute" on a dc breaker

    https://duckduckgo.com/?q=arc+chute+dc+breaker&t=fpas&ia=web

    They are common on the dc traction motor controller than runs the elevator up and down in your 50 story building.

    Similar pricipals in action.

    Not to mention modern skyscrapers have a lot more metal in them than the superstructure, typically metal floors the cement is poured on (metal floors welded to superstructure in many, many places), and steel wall studs, again fastened to the superstructure.

    In fact, you would be hard pressed to find any metal in a modern building that isn't "grounded" in multiple places.

    Thinking the "ground" connections at each and every electrical outlet in a skyscraper only go back to a "single point" is ignorant.

    My C.V. is I have (helped :)) put a few skyscrapers, and a MLB baseball park together.

    Rege
     
    Last edited: Nov 9, 2019
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  8. AI3V

    AI3V Ham Member QRZ Page

    Last edited: Nov 9, 2019
  9. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    You're right, another sparky here. I worked in the data storage field (disc drives, tape drives, magnetic heads and media). Never worked in AC power engineering, just the usual education and then my own personal experiences and learning. I know enough to be dangerous, as they say. Well, maybe a bit more than that but not by much!

    Being from the equipment side of things, single point ground has a particular meaning. So I was a little confused about exactly how you were using the term until I suspected that maybe you weren't including the outside rods and such. Thanks for your clarifying explanation.

    And yes, I know the difference between neutral and ground and how current should and shouldn’t flow.:)
     
    Last edited: Nov 9, 2019
  10. KF5LJW

    KF5LJW Ham Member QRZ Page

    I knew you did. , our paths have crossed and I seem to recall we have had conversations either here or Mike's forum. QRZ and Mike have several common members, some I know fairly well. I knew from the angle your questions were coming from tipped me off you were overlooking the big picture. Gave you a different point of view and you got it. Fixed a bad loop with a good loop, followed by careful arrangement of the specific conductors and specific function.
     

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