grounding a subpanel

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  #1  
Old 02-02-13, 11:32 AM
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grounding a subpanel

I am building a barn (24' X 32') and will be installing a subpanel (likely 60A). If I understand correctly NEC 2008 requires a separate grounding for the subpanel for which I plan to run the appropriate gauge wire to a ground rod. I will be installing a lightning protection system with two ground rods. My question is: can I ground my subpanel to the lightning protection system ground rod? Seems like it should not be a problem, as any lightning strike will go to ground, not to the subpanel. Thanks.
 
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Old 02-02-13, 12:11 PM
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You need a separate ground wire (EGC) back to the supplying panel to provide a low resistance path for clearing faults. Ground rods are for a totally different purpose (GEC) and you need those also for a detached structure.
 
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Old 02-02-13, 12:20 PM
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Thanks for you quick reply. I plan to run a 4-wire cable (2 hots, neutral & ground) from the main panel (house) to the subpanel in the barn. My question is whether I can use my lightning protection ground rod as my GEC for the subpanel, or do I need a separate ground rod.
 
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Old 02-02-13, 02:55 PM
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Not only can you use the grounding electrodes for the lightening protection for the panel grounding electrode you MUST tie all grounding electrodes together (electrically) for a proper installation.
 
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Old 02-03-13, 08:48 AM
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Thanks Furd. My lightning protection system will have 2 10' ground rods driven 4-6' out from the foundation at either end of the barn, all connected. As long as I run my subpanel ground wire to one of those rods, it will be part of the system. I presume this will work.
 
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Old 02-03-13, 10:26 AM
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Use nothing smaller than #6 solid copper for the grounding electrode conductor (GEC)and connect it to the ground rod with an acorn clamp below the surface of the ground. Bury the copper GEC.
 
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Old 02-03-13, 01:55 PM
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Will do - thanks again for the help.
 
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