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I purchased a pre wired shed that has a small panel in it. The panel itself has a single bus bar for neutral and ground, and two hot rails.

Currently all the circuits in the shed have ground and neutral bonded on that bus bar with the hots for each circuit in the breakers as you would expect.

Coming into the panel is a 4 conductor wire coming out of the generator. It is 2 hots, 1 neutral and 1 ground. The hots are wired into a 220 breaker, however I am not sure what to do with the ground and neutral.

Should the ground and neutral from the generator be bonded together via the bus bar? Or something else?

Any help would be appreciated.

  • What make and model is this generator, and are you wanting this to be utility fed in the future, or is the generator going to be the sole source of power? – ThreePhaseEel Jun 13 at 2:27
  • It's a Generac gp3300. I'm using the l14-20p plug on it. Right now it is the sole power source. – Brian D. Jun 13 at 2:37
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    By "right now" do you mean you will power it from another building in the future? Or will the future utility drop come Right Here? – Harper Jun 13 at 3:06
  • Also, what make/model is the panel in the shed? – ThreePhaseEel Jun 13 at 3:29
  • It is a Square D panel, not sure of the model. It does not have a separate bus bar for neutral and ground just one for neutral. No it will not be connected to another power source... – Brian D. Jun 13 at 16:31
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You only have one choice here

Your generator has a bonded neutral, according to the manual I was able to find for it online, and I also could not find any instructions for removing that internal neutral-ground bond. The bonded neutral is all well and good, and in fact the way it must be configured for standalone use, but this means that if you are using it to power up a structure, you will need to separate neutrals and grounds within the structure's panel, as if it were a subpanel.

As a result of this, you must go to a supply house or hardware store, get a Square-D PK7GTA ground bar kit, and fit it to your panel, as well as pulling the green bonding screw out of the panel in your shed. You will then wire up the inlet as a four-wire connection with neutral to the neutral bar and ground to the ground bar; likewise, all ground wires that are currently terminated on the neutral bar will need to be moved to the ground bar.

  • Thanks I will seperate them. – Brian D. Jun 14 at 2:14
  • Could you explain why you had to make panel that way? Is that for all portables? Or just that brand? – user101687 Jun 14 at 2:31
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    @RobertMoody OSHA & NEC rules for portable generators require them to have their neutral bonded to ground (EGC/chassis) for use as a standalone power source. Some portable generators provide a facility to remove the bonding means, though, as many simpler (read: two-pole/solid neutral) transfer setups are not compatible with having bonded neutral gensets plugged into them, but this is by no means universal, and the OP's Generac provides no instructions and seemingly no convenient facility for doing so. See this answer for the gory details. – ThreePhaseEel Jun 14 at 3:14
  • Was that a code upgrade around 2008? Starting to come back to me. Liked the (this answer).Helped a lot. – user101687 Jun 14 at 3:42

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