OT Lightning Protection- 2,000 sf residential new construction in rural NY - Page 4
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  1. #61
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    Quote Originally Posted by JST View Post
    Along with that "protected zone".... The rule I have been given is to go from the top of the tallest conductive item, down at an angle. Some say 30 deg from horizontal, some say 45 deg, and a few say 30 deg from vertical. Whatever they suggest, they agree that the area inside a cone at that angle is protected. I tend to think the 45 deg is the most realistic, but.... ymmv.

    maybe putting up a nice flagpole in the yard, close enough to the house to stay in the "cone of protection"...... depends on the house and allowable flagpoles.

    You can also take a look at an electric substation. There will be a heavy frame, with the various busbars etc hung from it, transformers under or near it, etc.. At the corners of the frame, and sometimes along it, will be vertical pieces of structural pipe. They are connected to the frame, usually at a vertical support, and they are generally at least a dozen feet high. They are usually spaced so that the distance between is a bit less than double the height of the pipes.

    The pipes are intended to intercept a bolt, and conduct it to ground via the structure. The blunt end of the pipe has very little ability to discharge via corona, that is generally from sharp edges or points that cause a large local electric field.

    You can take a cue from that as to what works, the electric companies hate replacing transformers etc, and are willing to spend a bit of money preventing that. They have had a good deal of time to figure out what is cheap but works.
    Not quite but close..

    The inverted cone is thought of as a director meaning the tall thing will attract from less tall things within that cone.

    Regarding current path we use a "falling doughnut".

    First side step...

    You generate electricity by movement of wire past mag field or field past wire, simple.

    Lightening strike is many thousands of volts and amps from DC to Daylight.

    This high current flows through whatever conductor from the tall thing to ground.

    Follow so far?

    Now imagine a cone from the top of the tall thing, cannot remember the angle so guess at say 60 degrees.

    Next imagine a doughnut with a diameter of the bottom of that cone.

    Drop that at the high thing and observe the path as it falls to the ground.

    The doughnut represents the magnetic field that results from the strike.

    Remember current flowing through a conductor generates magnetic field 90 degrees from the current flow.

    The with the current being great and frequencies from DC to daylight the mag field has same characteristic and as such this moving magnetic field will by normal physics induce massive currents in any conductor within the area covered by the falling doughnut.
    (wave travels from point a to point b as well as being caused by a.c. currents)

    Having things bonded to single ground helps to keep all at same potential.

    Motorola R56 calls for halo system where there is conductive ring around the top and bottom of the structure as these conductors can dissipate much of the generated energy.

    Things are bonded to bottom ring to minimize potential.

    The whole room may reach a few thousand volts above ground due to wave length of energy relationship to length of ground wire to ground but like birds sitting on hot wire no potential at the device so less damage as the doughnut passes.

    Had direct strike to tower on a 17 channel SMR, did no hard damage to any equipment at the building, no smoke but it did manage to confuse the controller and cause it to write to read only chips that could be either depending on board and as result controller turned into toaster... (electrical device that does nothing but generate heat).

    Replace eeproms with spares and good to go.



    Sent from my SAMSUNG-SM-G930A using Tapatalk

  2. #62
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    Quote Originally Posted by cg285 View Post
    on another note - sadly it is not in the middle of nowhere any more in fact it, and everything around it for a few miles, is leveled making way for the new 28 houses per acre development.
    WHAT??? 28 houses per acre??? That's less than 1600 square feet per lot, or 40' x 40'. That's crazy!

  3. #63
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    Quote Originally Posted by Tony Quiring View Post
    Not quite but close..

    The inverted cone is thought of as a director meaning the tall thing will attract from less tall things within that cone.
    .....
    That was the point.

    Induced currents is a different matter. Normally a Faraday cage is needed to block those effects.

    The tall conductive thing is simply to avoid direct strikes on things within the "cone of protection". Defense against what amounts to an EMP event is a separate matter.

    The lightning rods are NEVER, to my kniowledge, intended to protect against the magnetic effects. The entire idea is to prevent direct electrical current damage, to keep the strike conducted on the rods and grounding system, thus preventing the current from going directly through the building, which would be expected in many cases to cause a fire. It is essentially fire protection, not for protecting sensitive electronics.

    it is not expected to be foolproof protection against all things. Just good protection against lightning induced structure fires

  4. #64
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    I'm also in upstate NY - but per map in an area with much less probability of strikes. Also tucked into wood line at base of hill and an old fence line with large trees about 80 feet in front of house. So trees very close to house on two sides, partially on third side. All of them much taller than ridge line of house (which is about 28 feet off ground. Built the house in 1977.

    We have had lightning strikes somewhat close over the years, causing no damage, until four years ago. Summer storm late evening - wife and I had just gone upstairs to bed. Strike hit a large smooth bark (or as we call it pig nut) hickory to the front of the house. Totally lit up the room. Next morning a large scar visible for the path of the lighting going down the tree. Interesting part was when my wife went in the downstairs bathroom, which has a window on the front of the house. A small piece of bark had been blown off the tree and like a dart went through two layers of glass on the window, rather small hole but pieces of glass all over the floor. Looking at the piece of bark I never would have thought it could have done the damage it did. Would be an interesting problem to do the mechanics of it - I can think of one of my professors who would have had a field day with it.

    So guess I will be sticking with my 'tree protection system' and hope it continues to function well.

    Dale

  5. #65
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    Quote Originally Posted by steve45 View Post
    WHAT??? 28 houses per acre??? That's less than 1600 square feet per lot, or 40' x 40'. That's crazy!
    i questioned how they could do that but that's how the zoning changed. was time to get out
    maybe going vertical?

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    I want to build something in a rural environment, can you recommend a company that could help me?

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    The $8K quote for lightning protection is too high. OP is correct that what is needed are lighting rods with heavy gauge conductor (preferably inside protective conduit) down to heavy soil based grounding bar. The key feature is to make sure your roof mounted grounding rods are the highest objects on your roof that conduct electricity, and that you place them at strategic locations as dictated by your roof geometry. Generally speaking lightning strikes will seek the "lowest potential" object on your roof, e.g. the best grounded object.

    I have a standing seem copper roof on my house (yes, the entire roof) and decided to install about 5 grounding rods, each with its own soil based ground, and also tied this system directly to the roof. Feel better having done this, although in my area lighting strikes are rare.

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    there are countries where the houses are full of lightning rods. in other countries there are none. i alway found this quite weird.

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    Quote Originally Posted by Emmasterm View Post
    I want to build something in a rural environment, can you recommend a company that could help me?
    Like maybe a SPAM Cannery ?

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    I have a standing seem copper roof on my house (yes, the entire roof) and decided to install about 5 grounding rods, each with its own soil based ground, and also tied this system directly to the roof.

    I thought all the grounds should be bonded together not separated?

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    Quote Originally Posted by Bill D View Post
    I have a standing seem copper roof on my house (yes, the entire roof) and decided to install about 5 grounding rods, each with its own soil based ground, and also tied this system directly to the roof.

    I thought all the grounds should be bonded together not separated?
    They are, via the copper roof.

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    I don't think it depends on your building environment. If the company wants to work with you, then it will work anywhere. I can recommend something. It's about the company that relies on scaffolding services. It does delivery anywhere. You can click Find The Best Scaffolding Services - Pete Suen and read about the reviews of other people who have already had the opportunity to work with this company. If you have any doubts, I can give you an example myself. I have been working with them and have been impressed by the quality of the scaffolding, so I recommend it.

  13. #73
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    Quote Originally Posted by Emmasterm View Post
    I don't think it depends on your building environment. If the company wants to work with you, then it will work anywhere. I can recommend something. It's about the company that relies on scaffolding services. It does delivery anywhere. You can click Find The Best Scaffolding Services - Pete Suen and read about the reviews of other people who have already had the opportunity to work with this company. If you have any doubts, I can give you an example myself. I have been working with them and have been impressed by the quality of the scaffolding, so I recommend it.
    Oh looky here....the spammer has shown themselves....
    Go back to post #69, and read.

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    Proponents of such systems need to consider that a million volt lightning bolt just jumped a thousand foot or so air gap. Why would it notice a 12-18 inch rod with an inch of insulation between it and the roof structure and meekly follow a small wire to ground? While such systems may protect against a small or glancing strike, a full blown strike will not be detoured.

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    As I said before the theory is the rods equalize the charge before it can get high enough to jump to ground.
    Bill D

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    Quote Originally Posted by Superbowl View Post
    Proponents of such systems need to consider that a million volt lightning bolt just jumped a thousand foot or so air gap. Why would it notice a 12-18 inch rod with an inch of insulation between it and the roof structure and meekly follow a small wire to ground? While such systems may protect against a small or glancing strike, a full blown strike will not be detoured.
    What lightning follows is the most direct path to ground, largely ignoring nearby complicated paths. What matters in that the voltage rises quite abruptly, and not its personality defects.

    The standard way to estimate such things is the rolling sphere model:

    Rolling Sphere Method Lightning Protection Design in Florida

    https://hibp.ecse.rpi.edu/~connor/ed...esentation.pdf

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    Funny the 2 guys that did my house, garage, and shop did not even need scaffolding. One and off the roof with a ladder in just a few minutes each. Driving the ground rods and connecting the wiring took a lot more time.


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