I'm running a new sub-panel to my basement (the main panel is in the garage). I bought a 500' spool of 6 AWG THHN. The distance to the sub-panel is about 110' so I cut the spool into 4 x 125' lengths. I was planning on using one of the THHN cables as the ground. I just wanted to confirm that it would not be an issue running an insulated wire as the ground. I don't see why it would be a problem but just wanted to double check.

And as a follow-up, I saw one place that if you are using 6 AWG or larger you must use different colored cables. The spool I purchased is all black and I color coded each cable every couple of feet with colored tape. Is that going to be a problem or is that more of a inspector-by-inspector issue?

  • You should be fine on both counts, assuming of course that this is single phase power and that your "color coding" is red and black for power, white for neutral and green for ground. – JRaef Jun 2 '20 at 20:03
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    This is in conduit, right? – ThreePhaseEel Jun 2 '20 at 20:36
  • Yeah, good point. I assumed so because of mentioning THHN, but yes, it would have to be in conduit too. – JRaef Jun 2 '20 at 22:26
  • Yes, single phase and in 1-1/4" conduit. Thanks for the confirmation. – Brad Jun 3 '20 at 11:35

You have it backwards the larger sizes are allowed to be re identified not the smaller sizes. 6awg and smaller need to have the proper color insulation 250.119.A . The ground is allowed to be solid, stranded insulated or bare. But if insulated 4 and above can be reidentified at the terminations and splices.

  • So it looks like 250.119 is only referring to the ground having to be identified with proper color at 6AWG. Does that mean the conductors are ok to be identified just at the termination/splice points? – Brad Jun 3 '20 at 17:02
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    Well you asked about your ground, but the same rule is true for the neutral but gray or white are the required colors 6awg and smaller 200.6.A 1 & 2. Note it is common to identify L1 & L2 but not a big deal as they are a pure 180 out of phase meaning it doesn’t matter unlike 3 phase where they are 120 out and depending on the type of system the B phase will have a higher voltage to ground. – Ed Beal Jun 3 '20 at 18:09
  • Thanks for the clarification, I appreciate your help. – Brad Jun 3 '20 at 18:28
  • An upvote or accepting the answer is the normal thanks for the site. Accepting an answer helps others find answers if they have similar questions. – Ed Beal Jun 3 '20 at 18:30

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