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. AI3V

    AI3V Ham Member QRZ Page

  2. WA7ARK

    WA7ARK Ham Member QRZ Page

    Oh, you mean that $$$$ sales plug for PolyPhaser?
    AE8W likes this.
  3. AE8W

    AE8W Ham Member QRZ Page

    Yes. This is an ad for PolyPhaser.

    Notably absent from the references is the Motorola R56 (maybe?) Lightning Protection Guide. And, the only promotions of PolyPhaser that it exceeds the Motorola R56 reference is PolyPhaser.

    One alternative is Phoenix Contact. They do not market explicitly to amateur radio but to the much larger commercial sector (cell phone towers for instance)
  4. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    I attended a few of Rogers Blocks, Live training classes if was a week-long school and then we went out to Mountain Top Telecom sites, back in the 90s.
    They also fired up Big Bertha the lightning simulator that Rodger made. At that time DB products had a bunch of antennas they were zapping with it. The concrete floor was cracked under it. It would make your hair literally stand up.
    Rodger had some very sound principles and he did a lot of testing but there are so many different opinions on lightning protection.
    And I will tell you that he did cooperate with Motorola on some R56 testing back in the 1980s and 1990s.
    I followed most of his recommendations on our commercial sites and broadcast sites and it had very good results over the years we even had a device called a strike finder that Rodger had available for only a short time.
    It showed you whether your site actually had a hit or not and then you could upgrade it as needed. I had several sites that recorded a number of hits without any damage. But in testing my ground system after those hits the ground rods hedsor crystallized like glass around them and had to be replaced.
    I wouldn't have known it because the protection was working so good without the lightning strike finder monitor.

    So not knowing how will the system is working I wouldn't have known about the ground rods and would have probably had damage on the next hit.
    I have posted this before
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  5. KF5LJW

    KF5LJW Ham Member QRZ Page

    It is not a sales plug. It is how it is done professionally with a fully planned system. Get it YET

    SINGLE POINT GROUNDING which you do not understand. Polyphaser does NOT make 90% of what they are talking about. However they make the industry best Antenna Discharge Units. I have the book and it speaks of theories, principle, and BEST PRACTICES used in the industry.
    KX4O, N0TZU, W6KCS and 1 other person like this.
  6. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    I just reviewed this updated book that the later polyphaser owners had upgraded in a few places.

    No real changes from when Rodger Block wrote it in the late 1980s, by the way Rodger and his brother were both amateur radio operators and that's how they got into lightning protection.

    Most all the other lightning protection companies now agree on the Single point ground Theory that Rodger advanced.

    I would agree this is a good read for anybody designing or upgrading a tower site or their station.

    I have taught a number of grounding classes over the years and most of these are very sound principles, no matter whose protection equipment you're using.

    And remember "If you're not grounded properly, you're not protected".

    K4AGO likes this.
  7. KA7O

    KA7O Ham Member QRZ Page

    Here ya go - Do a google search for the Motorola R-56 "Standards and Guidelines for Communication Sites" - it's about 518 pages of PDF file. Available from many places.

    Good read!
    N1VAU likes this.
  8. W6KCS

    W6KCS Ham Member QRZ Page

    There's nothing wrong with the Polyphaser book, the mention of their products doesn't nullify the good info presented.
    WA7PRC, N0TZU, K0UO and 1 other person like this.
  9. AI3V

    AI3V Ham Member QRZ Page

    I believe they said the same thing, that there is nothing special about what they sell, and any similar product, installed the same way will work just fine.


    Several key points they make:

    Lightning is a AC phenomenon, so the inductance of your system becones critical.

    The idea of a true "single point" ground

    And the importance to understand even if you take care of the above 2 points, the tremendous magnetic field produced during an event can induce damaging currents into wires that are otherwise not connected.

    WA7PRC and K0UO like this.
  10. K4SAV

    K4SAV Ham Member QRZ Page

    That pdf document doesn't address the two most common questions asked by hams posting on forums. Neither does the often referenced R56 spec, an neither does the ARRL book. People like to avoid the tough questions. Those two questions are

    1. What do I do when the AC ground is on the opposite side of the house from the radio antennas.
    2. How do I protect my dipole hanging in the trees.

    So hams on forums make up answers for these questions, most of which are wrong.

    Polyphaser isn't immune from being wrong about some things either. My Polyphaser book has several pages of wrong calculations. I see in the referenced pdf they didn't clean up all of the problems. They calculate the inductance of a coax running down the tower as if it is widely separated from the tower. That is never the case. The coax is usually taped to a tower leg. If you add a bunch of coax lines running down the tower and use their calculated numbers, nearly all the current would run down the coax and almost none down the tower. That should be obvious to everyone as being incorrect.

    The R56 document contains good data but unless your shack looks like something at the base of a cell tower, it's unlikely you will be able to use most of the info in that document. If you are smart enough to figure out why the requirements in that document exist, you can use that knowledge and apply it to your system.

    Jerry, K4SAV
    W8IXI and WA7ARK like this.

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