Does it make a difference if Neutral and Ground Busbars are shared on 120/240 VAC Panel when I ad a Subpanel?

1. Main Panel vs. Subpanel Bonding Rules

  • In the main panel, the neutral (N) and ground (G) are bonded together. This is why you see neutral and ground wires on both bars in your main panel. The bonding ensures that any fault current has a direct path back to the source.
  • In a subpanel, neutral and ground must remain separate. This prevents unwanted ground currents (which can cause safety hazards and improper operation of circuit breakers).

2. Why Run Separate Neutral and Ground to the Subpanel?

  • The neutral wire carries current under normal operation, while the ground wire is only for faults.
  • If you bond neutral and ground in the subpanel, return current could travel on both, turning ground wires into active conductors—which is unsafe.
  • Keeping them separate in a subpanel ensures that only the main panel handles the neutral-to-ground connection.

3. How to Wire the Subpanel Correctly

  • Run 4 conductorsfrom the main panel to the subpanel:
    • Hot 1 (H1)
    • Hot 2 (H2)
    • Neutral (N)
    • Ground (G)
  • In the subpanel:
    • Keep neutral isolated (do not bond it to ground).
    • Connect the ground to a separate grounding bar, which is connected to the panel enclosure.
    • If the subpanel is in a detached structure, it may also require a grounding electrode (ground rod).
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I feel that you are very accurate here Billy. I look forward to seeing more contributions from you.
 
Thanks every one. I think the wise thing to do is to decline to help.
Washington state lets a non electrician do work but it must pass inspection.
I'm not taking chances, because my buddy might opt out of the inspection.

Thanks again.
 
Thanks every one. I think the wise thing to do is to decline to help.
Washington state lets a non electrician do work but it must pass inspection.
I'm not taking chances, because my buddy might opt out of the inspection.

Thanks again.
You might want to look at your drawing of the purposed installation. You are showing the line 2 (hot) going to the neutral bar and the neutral going to the line 2 lug.

Also, @Installer would you please update your profile to include your occupation?
 
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