First, thanks for all the excellent advice on this site.

While wiring an auxiliary heat strip to the 125A sub panel in my basement, I noticed that the sub panel does not have a grounding wire from the main panel. The main panel is 25 feet away in the basement. I would like to add the ground wire. The neutral bar on the sub panel is not bonded; I will add the grounding bar. I am in North Carolina. Here are my questions:

  1. Can I run the grounding wire on it's own zip tied to the whip carrying the hot and neutral wires (I cannot pull any wires through the whip as it is pre-made)?
  2. I'm planning on using #6 wire. Is that sufficient for the 125A sub panel?

1 Answer 1


In turn:

  1. Yes, you can run the grounding wire on its own as per NEC 250.130(C) point 5. Also, since you are using a #6 wire, it can be run unprotected as per 250.120(C), although Bare Armored Ground cable may be a better bet to keep dimwits with wire cutters at bay. However, zip-tying the new grounding conductor to the existing feeder cable is a violation of 300.11(C). You're better off simply fishing the wire where it needs to go, or having it take its own route to the panel.

  2. Yes, 6 AWG copper wire is an adequate grounding conductor for a 125A subpanel -- in fact, 6 AWG copper is good all the way up to 200A. However, if you had aluminum or copper-clad wire instead, you'd need a 4AWG wire for the job.

  • I'm borrowing this spot for a question. I need a sanely priced panel that has bolt down breakers in all slots, and can support one of those gen interlocks like I rave about. Bonus points if it is rated for 36VDC, right now it'll be mains but DC someday. . . Small (12) due to space limits. Any brand suggestions? Jun 10, 2019 at 21:56
  • @Harper -- hit me up on chat sometime and we can talk about it :) Jun 10, 2019 at 22:53

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