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I have seen other posts about this question, but mine is slightly different. I have a sub-panel that has a bonded neutral and ground bar, which I believe is against NEC2008. I understand the concern around this is if you had a short, and you touched both panels you could be killed. However my sub-panel is connected to the main panel by metal conduit. Does this negate the need for separate ground and neutral bars? I have a picture below for my setup. I don't understand the concern if the panels are connected, as I would think that would be the same thing as having a short and grabbing both sides of the same panel.

I'm asking because I am trying to wire in a new generator inlet box (you can probably tell why from the picture and the black wire coming in on the top left (that's the old generator inlet)).

I assume I would wire in the hots to the double breaker, and the neutral and ground to the bonded bar, or the separated bars if the question above is true. I have a Champion Tri-fuel generator with 7000 watts running, and a 30 amp connector (model 201176). The generator is neutral bonded to the frame, so I assume I would unhook this to have a floating neutral (Champion has a link on how to do this).

I really appreciate your help

enter image description here

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    Code is usually changed because people die, not for the fun of changing code. If that panel was in place before the code changed, then it is only recommended to change to newer code. If after the code changed then it must be brought up to code.
    – crip659
    Commented Dec 29, 2023 at 18:07
  • Completely understood there. The sub-panel was in place before 2008, and not something I installed (it was here when I bought the house). So are you saying that I should split the neutral and ground bars? And the metal conduit doesn't change anything? How about relating to the generator? I appreciate your help. Commented Dec 29, 2023 at 18:56
  • Generators are confusing, usually ask 10 people and get 15 different answers. You do need an isolating switch to turn off the main breaker when the generator is on/feeding the generator breaker. Splitting/unbonding the neutral and ground is about the easiest of jobs in a panel.
    – crip659
    Commented Dec 29, 2023 at 19:22
  • The black generator cable looks like it is black/yellow (to the breaker) + green. There should be a white neutral as well, because otherwise you only get 240V but no 120V power. Commented Dec 29, 2023 at 19:58

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The reason ground and neutral are bonded at only one place, the main entrance after the meter where the first cut-off breaker is (usually the main panel) is because of electrocution: the return electricity can flow through both the neutral and ground at once, electrifying all grounded metal, including grounded appliance cases. Then under certain failures, electricity will still flow on the ground, and can flow through persons getting in between the case and ground. So it's a bad idea to have more than one connection between neutral and ground. More than one neutral-ground bond can also mess up GFCI operation.

Yes, this panel has a bond between neutral and ground, see the green circled aluminum-looking bond wire doohickey:

bonded ground neutral bar

Remove that aluminum doohickey (it appears to unscrew off the back case and can be unscrewed out of the neutral bar) and the bond is removed in the panel.

It appears that there are no circuit grounds in this panel, they appear to be all in the main panel. And the conduit would ground the panel to the main panel box (make sure the conduit stub nuts are tight). There also appear to be very few neutral connections on this panel, they are almost all in the main panel, too, except for the Tork box. (I ignore the generator wire whip, which should be removed.)

When you remove that generator whip and wire in the generator inlet box, run the two generator hots to the generator breaker, and the generator neutral and ground back through the conduit stub into the main panel: Generator neutral to main panel neutral bar, generator ground to main panel ground bar.

The main feed breaker and generator breaker on this panel appear to have an interlock between them, which is good.

The neutral-ground bond in the generator should be removed, too, since the generator is connecting to the house, where there is already a neutral-ground bond. This means the generator cannot be used stand-alone at a job site, unless you put the generator's neutral-ground bond back just for job site use, then take it off again for house connection use.

One other thing to investigate: there is a white wire running from the main panel to the second single 15A breaker on the left from the bottom. While it is OK for a black/white pair to go to a double breaker for 240V appliances, like on your 20A lower right breaker, it is unusual for a white wire to be used as a 120V power wire, and may be against code. I'd check what that wire is feeding and see if there are some mistakes, or if only a wrong color jumper wire was used, and try to replace it with black instead. (Also the white wire on the 20A 240V double breaker should have color or tape around the jacket end to indicate it is intentionally being used as power.)

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    The bus on the left side does not seem to have that bond. Is it needed there if that bus is used for ground?
    – crip659
    Commented Dec 29, 2023 at 20:16
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    I believe that the black-plastic-wrapped bar at the top on both sides continues behind the breaker busses and bonds both bars together as two neutral bars. Also, the left bar is isolated on black standoffs like the right one is. I don't think there is a ground bar in this panel. Commented Dec 29, 2023 at 20:33
  • This response was so helpful, thank you! My main panel has bonded neutral and ground bars. If I unbonded my sub-panel bars, could I run independent wires from each bar back to the bonded bars in the main panel? And should I still remove that ground “doohicky” on the right? I figured I would make that the ground bar since it’s grounded to the panel. Commented Dec 30, 2023 at 1:31
  • @Select'DBA' -- the conduit provides the grounding connection between the two panels. That said, you will need to fit the subpanel with a separate grounding bar and move any grounding wires currently on the neutral bar to the grounding bar once you remove the bonding strap on the right. Commented Dec 30, 2023 at 5:35

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