I decided to add a small subpanel to accommodate extra outlets for my garage. I have an older Square D 100A main panel. Only cat no I could find is QOC-20m e6. First thing I noticed after pulling the panel cover to see how I should go about running service to the subpanel, is that all the neutral and ground wires are under the same lug per each respective circuit. Not ideal, but not unheard of.

Now, my question is, when running the neutral and ground to the new subpanel, would I connect both to separate lugs on the same neutral/ground bar in the main panel?

  • Hello, and welcome to Stack Exchange. A picture of the current panel (with the cover off) would be really helpful. Jul 12 '16 at 10:52

Since it is a subpanel, in your new panel, you will need to run the neutral to the neutral bar, run the ground to a separate ground bar, and make sure the green bonding strap/screw is removed so that the neutral bar is isolated from ground.

This is different from the main panel, where you can mix neutrals and grounds on the same bus.

  • Thanks for the response. I was asking more about the connection from the main panel. I know the subpanel can't have bonded neutral and ground. My main panel has neutral and ground mixed on the entire bus. I was just wondering if the neutral and ground feeding to the subpanel would both be connected to the same mixed bus in the main panel?
    – TMoore
    Jul 11 '16 at 23:59
  • My best advice is "when in Rome..." Just mimic what the last guy did (unless it's wrong). If the neutral-ground bus is a mess of white and copper spaghetti, pile on. If it's neatly separated, separate it neatly. Jul 12 '16 at 20:16
  • @Harper -- AFAICT -- what the last bloke did was put the neutral and ground wires together under each lug, one lug per circuit. Jul 12 '16 at 22:18
  • I've seen panels where that's allowed, and not a bad way to organize things. Jul 12 '16 at 22:35

When terminating the grounding and grounded (neutral) in the main panel, you can use any available, appropriately sized terminal on the ground/neutral bars. You can only connect a single conductor per terminal, so you'll need two open terminals to make the connection.

  • Thanks everyone. I appreciate the help, and just wanted to be sure. Just one of those moments where you have to step back and reassess. Lol.
    – TMoore
    Jul 19 '16 at 1:54

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