Confused on what to do in this situation, or if there is a problem... here's the setup:

I have a main panel and a subpanel. Main has ground bonded to neutral and sub panel has bonding screw removed to separate them.

I then have a METAL double gang outlet box that contains some splices.... inside this box is a junction that ties 3 of the main panel 20 amp 12 AWG wires together on an outlet branch and no devices. The #12 is THHN fed via PVC not EMT to the box.

I need to add a 3-way switch into this box (part of a 4-way circuit) that is on a 15amp branch that is driven from the subpanel. The new 14/3 romex coming into the box is just runners for the switch - so 3 hots and a ground.

My first instinct is just to tie all the grounds together, but if I do that then the 15a lighting circuit now has a direct ground path to the main panel that doesn't go through the subpanel route.

My other option would be to ground the 14/3 ground to the box and tie the 3@ 12/2 grounds together but not to the box.

Any pointers on the best approach and why?

  • 1
    Think as long as ground is not bonded to neutral in the sub panel, then all is good if grounds are together. Only problem with grounds is if removing a device breaks the ground path of other devices.
    – crip659
    Commented Jun 17, 2022 at 20:48

2 Answers 2


The 15A lighting circuit neutral goes via the subpanel. That's how "neutral bonding is not violated."

Grounds can be freely tied together. The whole thing could be wired in steel conduit and that would be every circuit's ground.

All the grounds in the subpanel are already tied to the ground in the main panel. The only thing you have to keep separated are the neutrals in the sub-panel.


Neutral is not ground.

So what Ecnerwal says.

Note that the main to subpanel run needs to actually have a ground "wire" or metal conduit pipe. If it is wired 3-wire no ground at all in cable or plastic pipe, with the N-G bond pulled... then you have a problem, because all that subpanel's grounding would come through this splice. The fix is to correct the subpanel wiring, e.g. by retrofitting a ground from subpanel to main.

  • 3
    subpanel ground has a #6 ground direct to ground bus on main. Commented Jun 17, 2022 at 21:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.