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Thread: Grounding temporary panels

  1. #21
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    Dec 2007
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    NE Nebraska
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    Quote Originally Posted by jumper View Post
    I have a vested interest. I am a patient.
    I'll just say you better have good insurance if you are cause of an auto accident that wrecks this truck

  2. #22
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    Quote Originally Posted by kwired View Post
    I'll just say you better have good insurance if you are cause of an auto accident that wrecks this truck
    Do not drive anymore.
    "Electricity is really just organized lightning." George Carlin


    Derek

  3. #23
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    Aug 2013
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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.
    Late to the party...
    The film and live events industry would grind to an absolute halt if we were required to drive a ground rod(s) at every spider box and cord-and-plug-connected temp panel. The ground would look like Swiss cheese. The only time ground rods are ever driven (and even then, not always) is when portable generators are used. The neutral and ground are bonded at the genny, and a ground rod is whacked into some patch of earth to keep the fire marshal and the dirt worshipers happy. The justification I've heard is... lightning strikes... nothing's gonna save your gear if a bolt from above hits your install directly, ground rod or not.

    I wouldn't worry about driving a rod(s) for a temp panel as described, so long as the feed to it were 4-wire (or 5-wire, if three-phase). The neutral and ground buses would of course have to be separated, and the panel treated as a subpanel.



    SceneryDriver

  4. #24
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    Quote Originally Posted by SceneryDriver View Post
    Late to the party...
    The film and live events industry would grind to an absolute halt if we were required to drive a ground rod(s) at every spider box and cord-and-plug-connected temp panel. The ground would look like Swiss cheese. The only time ground rods are ever driven (and even then, not always) is when portable generators are used. The neutral and ground are bonded at the genny, and a ground rod is whacked into some patch of earth to keep the fire marshal and the dirt worshipers happy. The justification I've heard is... lightning strikes... nothing's gonna save your gear if a bolt from above hits your install directly, ground rod or not.

    I wouldn't worry about driving a rod(s) for a temp panel as described, so long as the feed to it were 4-wire (or 5-wire, if three-phase). The neutral and ground buses would of course have to be separated, and the panel treated as a subpanel.



    SceneryDriver
    I think "Dirt worshiping 101, is typically first training inspectors get on their way to inspector certification.

    They don't even have to pay for that course, it is just given to them by inspector unions, associations, or whatever they belong to.

  5. #25
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    Quote Originally Posted by kwired View Post
    I think "Dirt worshiping 101, is typically first training inspectors get on their way to inspector certification.

    They don't even have to pay for that course, it is just given to them by inspector unions, associations, or whatever they belong to.
    No doubt. It's like the greatest thing these people can think of to make the world safe.

    "My kids wanted to go to the fair. I said no way. They don't have ground rods at any of their temp panels."

    "I never let my kids stay the night at a friends house till I personally make sure there are two ground rods driven at the house they are staying."

    "I never go anywhere without a ground rod and a driver in my trunk just in case"
    If you go and decide to dance with a gorilla the dance ain't over till the gorilla decides it's over.

  6. #26
    Join Date
    May 2005
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    Quote Originally Posted by ActionDave View Post
    "I never go anywhere without a ground rod and a driver in my trunk just in case"
    This one happens to be true when I have my Bosch rotary hammer with me.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  7. #27
    Join Date
    Jan 2018
    Location
    Kentucky
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    7

    No ground rod and gif protected

    First please do not drive ground rod. Connecting to earth with ground rods purpose is for removal of dc high pulse currents and to dissipate rogue electrons in inducing magnetic fields for example x0 inside of transformer. Been a long time since school so don't quote me on that but I do know ground rods serve only a few solutions and as a way to clear a fault is not one of them. It might even cause someone to more likely be injured if fault occurs. So first off here what ya can do from my experience using load centers as temp power. First determine origin of power. Is it coming from another panel or a transformer. If coming from panel the temp cables coming in needs to be four wire. The fourth wire in this situation would have to connect to ground bar and therefore clearing a fault at the source of electromotive force, which is the transformer feeding the panel you will be drawing power from. But in some situation a clear grounding path back to the source was the metal building bonded together but this is generally only used in industrial settings. Maybe some commercial when using transformer not connected to the utility pole like a square d. If this is an example of your source then take a bare 4/0 nothing less and bond to building and grounding bar. But most likely you will be connecting to a utility pole. In this case only make sure grounding bar is bonded as a appropriate size bonding jumper to nuetral. You will then need to take a 6 insulated (reason why insulated is because every breaker will be gfci and due to so many you will need to prevent electrical noise on ground) to a nec code approve grounding electrode. If a metallic light pole is nearby you can bond it to the bolts in the concrete with right grounding lug. This is the only way to bond it to that other than cad welding and ya don't want that. Only as a last resort where a nec define electrode cannot be used then you will drive a ground rod and in some town you will also have to drive a second one six feet away. Sorry been a while since I've dealt with load centers and residential so it may be code now to install two. This grounding is only for lightning protection. Make sure panel and all metallic parts are properly bonded to neutral not ground busbar. A third option would be to generate power from generators. In that case take use four wire. Bond generator x0 to the metal case. Doesn't come factorly bonded. Connect number 2 not number6 ech to xo in generator. Then drive two rods six feet apart and regardless of amp of generator use minimum number2 if not 4/0 insulated as ecg and connect to rods or other approved grounding electrode system nearby and close as possible. Now check load centers and make sure they are proper 120/240 or 3 phase 208. Then wire accordingly. Most factory portable load centers are 208 3 phase. But you can still derive 120 from them. The last thing you are required to do is install gfci approved receptacle mounted on temp station and install all gfci breakers. Run neutral to breaker from plug and then from breaker to neutral. In my experience due to extension cords being used we had a lot of tripping when required to use gfci breakers. If this happens remove wire from breaker coming from plug and then connect straight to nuetral. In this case, you will have to require all people who plug in to use a gfci interrupted apparatus at the plug not on the other end of cord connected to their equipment. Hope I helped. Please not I have been unfamiliar with proper code requirement using load centers in a fair ground or residential setting. However, my information is the proper way to safely install only because it is tested from doing it wrong as a helper starting out in temp power and wiring load center. One more tip make sure to confirm to Napa 70 e safety requirements while installing these load centers. Have personally seen an arc flash occur in a temp panel due to welding machines and panel being powered up in a dusty environment. Be safe and sorry if I sounded like a prick. Just trying to help.

  8. #28
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    Jan 2018
    Location
    Kentucky
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    Previous post

    Sorry in my previous post I did not notice you specified power coming from main panel. In that case no rods run number six to ground bar in main panel and number six from metallic enclosure on load center to a properly used egc, only for use in lightning strike. Also if I can suggest use xhhn 4 wire cable installed in pvc schedule 80 not glued to protect temp service conductors from damage. Most people would use so cable thnn. But because of high traffic areas I would go a little futher. Thanks

  9. #29
    Join Date
    Jul 2006
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    Quote Originally Posted by ajcobb.cobb View Post
    First please do not drive ground rod. ... Just trying to help.
    Please use a lot more paragraph breaks, I couldn't read that past the third line without my eyes glazing over.

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