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I'm adding a 100 amp subpanel to my detached garage and have a question about the EGC I've already pulled through the underground LFNC-B raceway.

Taking the advice from a similar post on this forum, I decided to use a 8 AWG bare solid copper conductor for my EGC in the underground raceway back to the main house. The other 3 conductors are 3 AWG THWN-2 stranded copper. I did double check the NEC tables to ensure these were appropriately sized for the underground feed portion of my run and ensured the conduit fill was less than 40%. What I failed to realize though (until after I won the good battle of pulling this set though the raceway) was that there is a section in the NEC that prohibits the use of solid conductors 8 AWG or larger in raceways:

"310.3 Stranded Conductors. Where installed in raceways, conductors of size 8 AWG and larger shall be stranded."

Dangit! Now I'm questioning why I didn't just use insulated green THWN-2 - it would have made my pull much easier! Rookie mistake.

So how bad have I goofed up here? Let's say the inspector fails to call this out. Is this a safety issue? What's the rationale for the rule anyways? To prevent numskulls like myself from trying to pull larger gauge solid wire through a raceway and possibly damaging the other conductors? Or is there more to it? Interestingly, there seem to be several exceptions in the NEC that do allow for using 8 AWG solid EGC in raceways (690.46 for Array Equipment Grounding Conductors for example).

I'm just trying to get a feel for the severity of this goof-up and if it's worth fixing if not required by the inspector. Any feedback from the experts would be much appreciated!

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  • I don't think you can use bare copper on pull but i'm not one of the experts. – JACK Jan 6 at 1:14
  • @JACK -- there's nothing I've ever seen prohibiting bare copper EGCs from being pulled thru conduit – ThreePhaseEel Jan 6 at 1:31
  • That's been moved to 310.106(A) and now says ""...not specifically permitted or required elsehwere"... so I'd check Article 250 which is about grounds. – Harper - Reinstate Monica Jan 6 at 2:23
  • @ThreePhaseEel Thanks. I've never seen or pulled a bare one, they've always been insulated. Stay safe out there. – JACK Jan 6 at 4:18
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This isn't an issue because you're dealing with an EGC

As it turns out, while using a stranded wire would have pulled more easily, you are in the clear with regards to your solid 8AWG copper equipment grounding conductor Code-wise. This is because NEC 310.106(C) (i.e. where your NEC 310.3 cite moved to in newer NEC editions) yields to other parts of the Code when they say things about what kinds of conductors are allowed in raceways:

(C) Stranded Conductors. Where installed in raceways, conductors 8 AWG and larger, not specifically permitted or required elsewhere in this Code to be solid, shall be stranded.

and NEC 250.118 point 1 explicitly permits the use of solid or stranded wire for an equipment grounding conductor:

250.118 Types of Equipment Grounding Conductors. The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:

(1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; and in the form of a wire or a busbar of any shape.

So, relax and enjoy a drink in the meantime, as you have absolutely nothing to worry about.

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  • Yes, one reason for approving bare grounds is they take less cross-section, and a stranded bare ground would take damage and turn into a mess. – Harper - Reinstate Monica Jan 6 at 2:37
  • Excellent! I will rest easier tonight knowing I'm not looking at a re-pull and what I've done is to code. If I ever have to do this again, I'll probably go with green THWN to make my life easier during the pull. – Jon Jan 6 at 20:27
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See also

250.62 Grounding Electrode Conductor Material. The grounding electrode conductor shall be of copper, aluminum, copper-clad aluminum, or the items as permitted in 2S0.68(C). The material selected shall be resistant to any corrosive condition existing at the installation or shall be protected against corrosion. Conductors of the wire type shall be solid or stranded, insulated, covered, or bare.

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  • 1
    The conductor in question, going between subpanel and main panel, is an equipment grounding conductor, not a grounding electrode conductor.. right? The GEC is what connects sub or main panel to their respective ground rods, ufer, or what-have-you, while EGC is what bonds ground between the panels? – Greg Hill Jan 6 at 2:52
  • @GregHill Right. – Harper - Reinstate Monica Jan 6 at 18:06

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