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Metal Tower vs Lightning...

  1. Jun 15, 2017 #1
    I have an 80 ft metal tower that is cemented into a dirt ground. It houses two small antennas to send and receive signals for wifi. This tower's power source is not a home. It has a dedicated line that runs directly to its own power meter. This tower is about 300 ft from a concrete home. The Internet company says the tower itself is already grounded. I have other people who are saying it is extremely dangerous to not have it properly grounded with a copper rod. What are the potential dangers if lightening were to strike this tower? I live in Nicaragua where reliable knowledge is hard to find!! I would appreciate any insight!
     
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  3. Jun 15, 2017 #2

    berkeman

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    Welcome to the PF, Jane. :smile:

    Can you take a few pictures and use the UPLOAD button to post them here? Do you see any cable to a grounding rod at the base of the tower? Where is the power meter? The grounding mechanism may be part of that section...
     
  4. Jun 15, 2017 #3

    Baluncore

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    The grounding requirements of metal towers are well understood and followed by the engineers who specified and installed the tower. If the metal tower was not properly earthed, a lightning strike could damage the concrete footings or the radio equipment on the tower. Damage to the concrete footings might allow the tower to fall. The internet company and installation engineers do not want that to happen and so will have installed one or more reliable lightning conductors across the concrete from the tower to the ground. You can probably see that bare metal conductor at the base of the tower where it crosses the concrete footings and enters the ground. Go take a look and see what method was used to earth the tower. The lightning conductor will be separate from the power supply ground.

    You and the concrete house have no more to fear from lightning than usual. You are probably slightly safer with an 80 ft tower, 300 ft away, than without the tower. Indeed it would actually be safer if the grounded tower was closer to the concrete house.

    There is no possibility of the lightning getting into the local power grid from a grounded tower. Lightning is always striking the power company's grid of wires, which are designed to survive lightning, so things are as safe as they ever were, even with the tower nearby.

    The tower will have been properly grounded. You may have found some people who like to get their fun by spreading fear, uncertainty and doubt.
     
  5. Jun 15, 2017 #4

    mfb

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    @Baluncore: In North America and Europe: Sure.
    In Nicaragua: ?
     
  6. Jun 15, 2017 #5

    Baluncore

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    Nicaragua follows the NEC standards. Are you suggesting that the wiring code in Nicaragua is insufficient? Or that the local power supply authority would allow a meter to be connected without proper grounding of both the power supply and of the structure?
    The internet company is not an uneducated electricity thief, they need a reliable system. Not grounding the tower structure would be a false economy.
     
  7. Jun 16, 2017 #6

    davenn

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    @mfb is hinting at, and I kinda agree, Nicaragua is a 3rd world country and what I have seen in many 3rd world countries, that I have visited, is that rules and reg's are rarely followed :rolleyes: and mains / all cabling is usually pretty bad

    heck for that matter, I have seen some horrific 120V mains house wiring even in the USA in my visits there that made me cringe


    Dave
     
  8. Jun 16, 2017 #7

    Baluncore

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    If that is truly the situation, then there is no problem.

    BUT IF the tower is not grounded, there are two worst case possibilities;
    1. The footings are destroyed by a massive lightning strike and the tower falls. The closest it could get to the house is 220 feet away.
    2. The tower could deliver the lightning to the local supply. Before the tower was placed there, the overhead supply cables were probably the direct target for local lightning. The supply will have survived previous strikes, so it must must be safe, correctly earthed and protected.

    I see no reason why a poorly earthed 80 ft tower would have safety implications to a concrete building 300 ft away. There is no evidence that the tower is poorly earthed, that was just suggested by some uneducated FUD-mongers.

    You can't blame an entire country for your poor expectations. The more you describe Nicaragua as a 3rd world country with poor wiring standards, the more it will fulfil that expectation. Nicaragua is where it is today because of the political and economic actions of 1st world countries.

    If the Chinese build the Nicaragua Canal to compete with the Panama Canal, will you belittle Nicaragua even more?
     
  9. Jun 16, 2017 #8
    Thanks everyone for your quick responses! The tower IS NOT grounded, the wifi company said it is buried in the ground therefore "naturally grounded".

    The tower has 4 cables cemented in the ground to also hold it in place. My biggest worry is not the tower falling over.

    My worry also has nothing to do with damaging the equipment as it is guaranteed to be replaced by the wifi company.

    My biggest fear is that it could be unsafe and somehow zap someone near the house... I was told upon a strike that if all that energy is not grounded then it is very dangerous to anyone nearby.
     
  10. Jun 16, 2017 #9

    Baluncore

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    If it is not well grounded, then nearby probably means within 12 ft of the base of the tower or of a guy wire.
    You will be quite safe at the house.
     
  11. Jun 16, 2017 #10
    What a relief!!! Thank you so much for the information.
    I have one more question for you: This tower's original power source was a water pump that is connected to the house about 100 feet away. I am switching it over to the independent power source of a meter. While waiting for the power company to make the installation, it is still hooked to this water pump. There is a breaker at the water pump that connects to the tower. The electrician assured me that when that breaker is switched to the OFF position, no damage can happen to the pump or the house if the tower is struck. Is this true?
     
  12. Jun 16, 2017 #11

    Baluncore

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    If the foot of the tower is in contact with the earth then it is probably sufficient to open the breaker to isolate the tower from the pump and house.
    Once the new metered power is connected at the tower, the cable from the breaker to the tower should be removed. That will separate the systems and make the pump and house quite independent of the quality of the tower ground.
     
  13. Jun 16, 2017 #12

    jim hardy

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    Is there a third "grounding" or "bonding" wire connecting your breaker box or pump to the tower ? Sometimes it's the metal conduit itself, sometimes it's a green or bare wire inside the conduit, sometimes it's a bare wire around which the other two are wrapped and strung overhead.

    That's a path for lightning to get from the tower into your house. When they show up to finish the job you want them to remove that wire and any metal conduit going to the tower.
     
  14. Jun 16, 2017 #13

    jim hardy

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    Long ago, in a thread far away....

    Grounds along the way will help.
    But don't leave the receptacle grounds in your house connected by a metal conductor all the way to that tall tower.
    Make lightning come through the earth to get in and it'll probably go someplace else instead.
     
  15. Jun 16, 2017 #14

    OCR

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    My holler "Gaahhh" is more akin to a screech, as such... AAAaaahhh !!

    I embarrassed myself in front of my wife with that noise when, by accident, I came in contact with her electric garden fence... :blushing:
    Well, actually... I embarrassed myself in front of myself, too. [COLOR=#black]..[/COLOR] :oldgrumpy: [COLOR=#black]...[/COLOR]lol
     
  16. Jun 16, 2017 #15

    OCR

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    Yeah, I think we always called that... Triplex . ?
     
  17. Jun 17, 2017 #16

    jim hardy

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    The circuit breaker will disconnect the two power(Hot) conductors
    but will not disconnect a Neutral or a Bonding conductor .

    That's why (s?)he needs to verify they're gone.

    Of course Janelle has an 80 foot metal tower not a wood power pole.
    but principle is the same.....
    Triplex4Tower1.jpg

    Lightning at top of pole has an all metal path into your house.
    That bare copper wire down the pole carries a lot of it directly into earth. It goes to bottom of pole where it's wrapped into a spiral for max surface area to conduct as well as possible..
    Ground rod at house service entrance helps too.
    Still,
    During that brief instant when it strikes the pole your household appliances are hardwired through their three wire grounded cords directly to the bottom of that lightning bolt. That's what almost got me.

    @JanelleNica
    That wifi tower is a lightning rod, as you suspect. Its wiring ought to be separated from your house wiring by as much physical distance as you can arrange.


    old jim
     
    Last edited: Jun 17, 2017
  18. Jun 17, 2017 #17

    jim hardy

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    PS

    that's why , when copper thief urchins chop a piece out of that unimportant looking bare wire running down your pole, you should inform the power company right away..
     
  19. Jun 17, 2017 #18

    OCR

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    :thumbup:
     
  20. Jun 17, 2017 #19

    jim hardy

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    Thanks, @OCR and @davenavenn and @dlgoff ...

    old jim
     
    Last edited: Jun 17, 2017
  21. Jun 17, 2017 #20

    dlgoff

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