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Old 07-06-2011, 08:12 PM   #1
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which grade wire to use for grounding subpanel


i will have a 50A subpanel in my shed with gauge 6 wire. i am not sure whether i need to use outdoor (THHN?) gauge 8 with insulation since it will go outside (about 6" between the shed and the grounding rod) or regular NM gauge 6 will suffice since it is just ground.

i was also curious whether the 6" outside segment of the wire needs to be protected in conduit or can it just be exposed.

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Old 07-06-2011, 08:35 PM   #2
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which grade wire to use for grounding subpanel


#8 copper is sufficient, you can use 6 if you have some. Has to be copper as it’ll be in contact with the earth. If you have some, strip the insulation off and run it bare.

#6 needs protection if subject to damage.

#8 needs protection.

Sleeve it with a small section of Ĺ” PVC if you have some left, if you need.

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Old 07-06-2011, 09:27 PM   #3
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which grade wire to use for grounding subpanel


yes but can the wire be regular NM or does it have to be graded for outdoor use (THHN) ?

also, when you say "protected", does that mean use conduit between the shed and where it goes underground? or all the way to the grounding rod?

and how deep does the top of the grounding rod need to be below grade?

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Old 07-07-2011, 05:16 AM   #4
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which grade wire to use for grounding subpanel


Bare wire isn’t graded, like thhn, thwn, mtw. It’s the insulation that’s graded. Bare copper pulled out of a cable like romex can be used.

The sleeve covers the part exposed as it runs down the side of the shed, once it goes into the ground, doesn’t need sleeving anymore. Bury it about 6” or more and you should be good.

The tops of the rods need to be flush or below the dirt. I usually put them an inch or two below. Leave the tops exposed for inspection.
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Old 07-07-2011, 03:04 PM   #5
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which grade wire to use for grounding subpanel


i was under the impression that, if ground wire is running solo, it has to have insulation, i.e. can't be bare like it comes in a cable.
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Old 07-07-2011, 03:12 PM   #6
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which grade wire to use for grounding subpanel


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i was under the impression that, if ground wire is running solo, it has to have insulation, i.e. can't be bare like it comes in a cable.
Wrong impression.
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Old 07-09-2011, 02:01 PM   #7
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which grade wire to use for grounding subpanel


are you saying that inside the shed i can have an uninsulated copper ground wire even outside conduit?
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Old 07-09-2011, 02:37 PM   #8
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which grade wire to use for grounding subpanel


The grounding electrode conductor? What size are you running?

In a nutshell, #6 and larger can be run exposed as long as it’s not subject to damage, otherwise protection is needed. #8 and smaller has to have protection.

If it’s exposed, it has to be fastened, in conduit the conduit needs to be fastened.

Sorry Vic, also forgot to mention before that it has to be continuous from the panel to the first ground rod. It can be continuous from the first rod to the second, but doesn’t have to be. Though it’s just as easy to do it continuous, and wouldn’t require a 3rd rod clamp.
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Old 07-09-2011, 03:31 PM   #9
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which grade wire to use for grounding subpanel


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In a nutshell, #6 and larger can be run exposed as long as itís not subject to damage, otherwise protection is needed. #8 and smaller has to have protection.
what do you mean by "protection" ? insulation or conduit.

and in my nutshell, i wanna run whichever gauge grounding cable i will need to run from my 50A subpanel to the rod in order not to have to use conduit. so my question is, is it #6 with THHN insulation, NM, insulation, or no insulation at all. i really want to avoid the drudgery of running conduit as well. this wire will be exposed as the framing in the shed is exposed, i.e. no drywall or paneling. i am trying to do it in the most minimal, efficient, and elegant way.

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Old 07-09-2011, 03:40 PM   #10
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which grade wire to use for grounding subpanel


Protection would involve running the conductor in a conduit sleeve, or you could install something over where the conductor runs like plywood.

You will not find the #6 or #4 in NM. It can be bare or insulated green.
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Old 07-09-2011, 03:51 PM   #11
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which grade wire to use for grounding subpanel


can i just take THHN insulated #6 or #8 single wire and run it exposed (no conduit) from the subpanel to the rod and staple it to the framing?

it is the same wire that i used to run from the house to the shed (used 3 THHN #6 for two hots and a neutral and 1 THHN #8 for the ground). can i take the same thing and run it exposed from the subpanel to the rod ? i can put it in a little 1/2" elbow between where it exits the shed and goes underground outside , that would be simple enough but i would like to avoid the grueling effort of running conduit between the subpanel and where it exits the shed inside.

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