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Thread: Lightning Protection in Existing Building

  1. #1
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    Lightning Protection in Existing Building

    Hello!

    I am working on a lightning protection project that is assessing the protection of an existing industrial facility. The building is OLD, and no one/no document seems to be able to show the grounding layout of the building (specifically below grade). In addition, every inch of ground surrounding the building for a good distance is concrete. We have about eight down comers from the building per our lightning protection plan. The building is also over 60' tall, so a ground ring is required per 780.

    A suggestion has been given that the contractor will have to "score" the concrete around the entire building, bury the ground ring and rods, and then fill. Is this the best way to go about retrofitting a building with lightning protection? It seems like such a labor intensive process. Does anyone have a better method for doing this sort of work?

    Any suggestions would be appreciated!!
    Thanks,
    --Nate from Baltimore

  2. #2
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    Directional boring perhaps?

    There's only so many ways to get stuff underground.

  3. #3
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    Quote Originally Posted by BlaineXD View Post
    Hello!

    The building is also over 60' tall, so a ground ring is required per 780.
    Would you provide the specific 780 reference for this requirement? Not one that I am familiar with.

  4. #4
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    Quote Originally Posted by publicgood View Post
    Would you provide the specific 780 reference for this requirement? Not one that I am familiar with.
    4.14.2* For structures exceeding 60 ft (18 m) in height, the interconnection of the lightning protection system grounding electrodes and other grounded media shall be in the form of a ground loop conductor.

    Hope that helps. In any case, a ground ring is going to be installed at the site.
    Thanks,
    --Nate

  5. #5
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    Quote Originally Posted by BlaineXD View Post
    4.14.2* For structures exceeding 60 ft (18 m) in height, the interconnection of the lightning protection system grounding electrodes and other grounded media shall be in the form of a ground loop conductor.

    Hope that helps. In any case, a ground ring is going to be installed at the site.
    Thanks,
    --Nate
    That does help. I did not notice that before. A co-worker of mine found this reference in 780 that may be helpful:

    1.4  Retroactivity. The provisions of this standard reflect a consensus of what is necessary to provide an acceptable degree of protection from the hazards addressed in this standard at the time the standard was issued.
    1.4.1  Unless otherwise specified, the provisions of this standard shall not apply to facilities, equipment, structures, or installations that existed or were approved for construction or installation prior to the effective date of the standard. Where specified in this standard, the provisions of this standard shall be retroactive.
    1.4.2  In those cases where the authority having jurisdiction determines that the existing situation presents an unacceptable degree of risk, the authority having jurisdiction shall be permitted to apply retroactively any portions of this standard deemed appropriate.
    1.4.3  The retroactive requirements of this standard shall be permitted to be modified if their application clearly would be impractical in the judgment of the authority having jurisdiction, and only where it is clearly evident that a reasonable degree of safety is provided.

  6. #6
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    Quote Originally Posted by jaggedben View Post
    Directional boring perhaps?

    There's only so many ways to get stuff underground.
    Hmm one wonders about the contact with earth in a directional bore.


    I know what I don't know, and I know where to go to find it!

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