ground terminals in subpanel

Old 01-12-02, 09:11 AM
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Question ground terminals in subpanel

I am wiring a new detached garage. I have a Square D Q Load Center subpanel, 100A with 8 spaces. I understand I could have as many as 16 circuits if I used the skinny breakers.

The ground bar the panel requires has only 7 terminals on it. If I use one to connect my ground from the main panel, and one more for the conductor to the ground rod, I'm down to 5 terminals. There is only the one bar listed as acceptable for this subpanel.

How do I add more terminals? Do I put another ground bar in one of the other locations the box has and run a conductor between them?

Thanks for any help. I want to be sure I'm doing the right thing.
Old 01-12-02, 12:06 PM
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You are usually allowed to put more than one grounding wire under a screw. But you need another bar anyway for the neutral wires, and you're not allowed to put more than one neutral under one screw, so buy one long enough. As has been stated in this forum many, many times before, you must keep the grounds and neutrals isolated from each other in a subpanel.
Old 01-12-02, 01:02 PM
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Also consider installing a ground rod (grounding electrode) at the detached garage.
Old 01-12-02, 03:03 PM
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Thanks for your replies.

The sub panel I have already has the neutral bar attached, separate from ground. I do have a ground rod at the garage.

Can I really double up on the grounds? Or would it be preferable to install a second ground bar? If I have two bars, do they need to be connected by a conductor or is the mounting to the box sufficient?

I have 50A going through 6 AWG UF cable to the garage. What is the correct conductor to use for between the subpanel & ground rod? Insulated or bare?

Thanks again!
Old 01-13-02, 04:28 AM
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If you have a white neutral wire and a green or bare equipment grounding conductor ran from that main bulding to the panel in the garage then you must have a main breaker in that panel in the garage if you have more than 6 branch circuits available [six circuit panel] {7 circuit panel or more must have a main breaker in that detached garage panel bolted or clipped into place permenently}. Separate the neutrals and grounding conductors on separate bars with the neutral conductor not in contact with the grounding bar of the metal of the panel box. The grounding electrode conductor connecting the ground rod to the equipment grounding bar can be an 8 awg cu conductor, you must not use an aluminum wire in direct contact with the earth.

All the rules above are in the detached garage.

If you are working in the main panel in the main structure then you can join the neutral and grounding conductors on the same bar and as John said mix more than one grounding conductor in the same hole in the panel is ok but only one white neutral wire can be in one hole on that bar for each white neutral conductor.

Hope this helps


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