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Burbank, CA

I added a 125 A subpanel to my detached garage (2/0 feeders), and ran copper ground between it and the main panel. I’m now installing a pair of grounding electrodes for the subpanel, and want to know if there are any requirements for how the bonding jumper is run from the electrodes into the building and into the sub panel.

The feeders run through PVC conduit underground from the main house, come up outside of the garage, and penetrate the garage wall about 15" above the ground. Inside, this goes along an interior wall about 5' before it curves up to go into the bottom of the surface-mount breaker panel.

Can I just stick the #6 THHN grounding jumper through that same penetration beside the PVC conduit, and run it exposed next to the feeder conduit? Or does it need to go in its own conduit from below grade where the rods are, through the exterior wall, and along the interior wall?

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The NEC requirements for protection are pretty slim, you can read them here.

The NEC doesn't really cover the wall penetration, that is a structural issue that is covered by the building code which usually defers to the siding manufacturers instructions on how to prevent water damage. Usually those instructions specify how to seal around individual penetrants only.

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    Yeah, best practice for exterior penetrations is "one thing per hole" Commented Apr 15 at 3:48
  • Hmm. I think 8 ga is suitable for my 125 A subpanel, and the referenced code says “Grounding electrode conductors smaller than 6 AWG shall be protected in RMC, IMC, Schedule 80 PVC, RTRC-XW, EMT, or cable armor.” #6 doesn’t necessarily need that, unless “exposed to physical damage,” but what does that mean?
    – Rick
    Commented Apr 16 at 20:42
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    @Rick "exposed to physical damage" isn't defined, so the inspector wins. NEC 90.4(B) applies: The authority having jurisdiction for enforcement of the Code has the responsibility for making interpretations of the rules, for deciding on the approval of equipment and materials, and for granting the special permission contemplated in a number of the rules. Commented Apr 16 at 23:42

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