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Thread: Grounding temporary panels

  1. #1
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    Grounding temporary panels

    Our community wants to provide temporary load centers for downtown events such as parades and festival events. These would be 100 amp panels set up on portable stands, fed with 4-wire assemblies and intended to be plugged into a permanently installed receptacle for power. Would each of this locations be required to establish a new grounding electrode system or is the 4-wire adequate for grounding. All of them will originate from a main panel location. Since each of this portable panels could be considered a separate structure I am thinking an electrode system might be required a each location. Still in preliminary design but requesting any thoughts.

  2. #2
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    We used construction spiders for that type of application. had about 20 but each time set up required a permit and inspection, so went with SS boxes with 8 GFCI receptacles in them.
    Moderator-Washington State
    Ancora Imparo

  3. #3
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    Quote Originally Posted by 102 Inspector View Post
    Our community wants to provide temporary load centers for downtown events such as parades and festival events. These would be 100 amp panels set up on portable stands, fed with 4-wire assemblies and intended to be plugged into a permanently installed receptacle for power. Would each of this locations be required to establish a new grounding electrode system or is the 4-wire adequate for grounding. All of them will originate from a main panel location. Since each of this portable panels could be considered a separate structure I am thinking an electrode system might be required a each location. Still in preliminary design but requesting any thoughts.
    Is a feeder allowed to be fed from a receptacle? Just curious.

    I agree it is a structure. You are probably going to have to create a grounding electrode system for each one. It will probably need to be two ground rods 6 feet apart. The irreversible connection requirement is going to make it messy.
    Bob

  4. #4
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    I would call a panel on a stand equipment not a structure. The 2017 NEC clarified what classifies as a structure.

    Structure. That which is built or constructed, other than equipment. (CMP-1)
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  5. #5
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    The fact that its temporary does not change the code requirement for grounding and bonding, its a feeder panel. Now if you can use a spider, then a grounding electrode system is not required.
    On your comment about the 4th green wire, that is for bonding, ground rods are for lightning.
    Moderator-Washington State
    Ancora Imparo

  6. #6
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    Quote Originally Posted by infinity View Post
    I would call a panel on a stand equipment not a structure. The 2017 NEC clarified what classifies as a structure.
    I agree the equipment is not"structure" but the stand they build to mount in on certainly is.
    Bob

  7. #7
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    I do not see it as a permanent structure, no GES required IMO.

    Quite a common set up.

    Tom’s spider boxes are great but if you are building them, make sure you use all the correct parts, not gonna list all the stuff, assuming you know what is involved.

    Biggest concern to me is making sure stands are properly secured so they do not tip over. Easy to do, stakes and what not.

    A small roped or cautioned taped “fence” around the stands also. Don’t want people, bikes or whatever knocking into them.
    "Electricity is really just organized lightning." George Carlin


    Derek

  8. #8
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    Quote Originally Posted by tom baker View Post
    The fact that its temporary does not change the code requirement for grounding and bonding, its a feeder panel. Now if you can use a spider, then a grounding electrode system is not required.
    On your comment about the 4th green wire, that is for bonding, ground rods are for lightning.
    Not trying to be smart alecky, but if there is an outdoor event and a storm with lightning is coming, it prolly is gonna get canceled or postponed. OP is in mid west, they are smart about stuff like that because tornadoes can easily follow.
    "Electricity is really just organized lightning." George Carlin


    Derek

  9. #9
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    Quote Originally Posted by jumper View Post
    I do not see it as a permanent structure, no GES required IMO.
    It seems to me that as a temporary installation, article 590 applies.

    590.1 Scope. The provisions of this article apply to temporary
    electric power and lighting installations.
    590.2 All Wiring Installations.
    (A) Other Articles. Except as specifically modified in this article,
    all other requirements of this Code for permanent wiring
    shall apply to temporary wiring installation
    s.
    So unless this article specifically exempts a temporary structure (with more than one circuit) from having a GES, it is still required by code. I looked through article 590 and did not find any exemption to the GES requirements.

    The best arguement against the GES requirement might be the wording of "served" as regards the structure. If nothing on the structure is served by any of the circuits one might make an argument that a GES is not needed.
    Bob

  10. #10
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    Assuming these are just basic 1-3 day events, no one I have ever heard of was running around driving rods into local parks, near sidewalk or whatever.

    If these were large commercial events like major fairs or such, I would agree, but a small parade with a few floats, a marching band and like that is over in 3 hours. Nope.

    Even a two day tomato festival is not a likely to be a major venue.
    "Electricity is really just organized lightning." George Carlin


    Derek

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