Connecting subpanel to groundig rod

1289 Views 11 Replies 8 Participants Last post by KarenStein, Jun 4, 2016

scotjamn

Discussion Starter · Jun 1, 2016

I have found plenty of helpful diagrams and posts on connecting my planned detached garage subpanel to the main service. Routing the two hots, neutral, and ground to the subpanel via the underground conduit and making the service entrance to the outbuilding are easily understood.
Now for what might be obvious to everyone but me - for the physical connection from the subpanel to the grounding rod, what is the best way to route the ground wire? This is new construction so I don't have to contend with an interior wall or insulation. Is it as simple as drilling a hole in the exterior wall and weatherproofing around the hole after pulling the wire through or is there a gland plate /bulkhead that improves this connection? As I said, it may be something I've missed, but I can't say that I've seen a clear picture or video on this part of the plan.
Thanks in advance.

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Barjack

· #2 · Jun 1, 2016

What you described sounds ok to me.

The grounding electrode conductor (GEC) needs to be copper #6 (any smaller and it would need to be sleeved in conduit for its entire run), and protected from physical damage where exposed.

The clamps that connect the GEC to the rods need to be listed for direct burial, even if they are used above ground.

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rjniles

· #3 · Jun 1, 2016

Since this is new construction you should install a UFER ground. Concrete encased electrode.

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Jim Port

· #4 · Jun 1, 2016

The clamps that connect the GEC to the rods need to be listed for direct burial, even if they are used above ground.

Unless the rod is longer than 8' the rod needs to be flush or below the ground in order to have enough contact with the esrth.

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scotjamn

Discussion Starter · #5 · Jun 2, 2016

Thanks for the feedback. However, I will re-state the question... my chief concern is not so much the grounding rod itself; my question was more aimed at the best way to transition the ground lead from the interior panel, through the wall, to then connect to the rod.

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joed

· #6 · Jun 2, 2016

Conduit down the wall for protection. An LB where is exists the wall to make the turn. Bury it once under ground.

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AllanJ

· #7 · Jun 2, 2016

If the building has reinforced concrete construction below grade and was built after a certain date (I don't have that handy) then it must have a concrete encased electrode ground consisting of at least 20' of embedded rebar which may be tie wire bonded sections. CCE electrodes are often referred to as but not exactly synonymous with Ufer electrodes. Ground rods and, if applicable, a water pipe electrode are still required.

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Jim Port

· #8 · Jun 2, 2016

The NEC does not require any supplemental electrodes when a CCE or Ufer is used.

The GEC should be as straight as possible.

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brric

· #9 · Jun 2, 2016

IMO there are only rare instances where the grounding electrode conductor requires protection with conduit. Without seeing the actual installation, I would most likely exit the electrical panel, route the conductor inside the wall cavity exiting the wall near ground level to the first grounding rod.

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KarenStein

· #10 · Jun 2, 2016

Who says the the ground rod needs to be outside?

Consider drilling a hole through the shed foundation, and placing the ground rod there.

If the rebar of the slab is available, connect the wire to it and -voila!- you have a 'concrete encased electrode.'

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Jim Port

· #11 · Jun 3, 2016

Rebar in a slab is not a CEE. It needs to be in the footer.

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KarenStein

· #12 · Jun 4, 2016

I hope this link works; it is to some artwork from an electrical trade magazine, and indicates that rebar in the slab itself is acceptable:

https://images.search.yahoo.com/sea...m/nec/code_qa/250-52A3-01web.gif&action=click

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