We have 400 amp service in our house. There are two 200 amp subpanels. The one is the primary subpanel for most of the house that would need a generator connected to it. The main box is outside and has the meter integrated, so I cannot access it without breaking the seal. Is it possible (code compliant) to use an interlock kit on the primary subpanel with a 50 amp breaker to the generator inlet? With the interlock kit making sure the main 200 amp breaker for that subpanel is turned off, would there be any possibility of a backfeed? Thanks

  • In most places a mechanical interlock is compliant. But you need to check your local codes, which may vary a bit, before doing this.
    – jwh20
    Commented Dec 13, 2022 at 18:34
  • Does your main box have a main breaker or breakers inside it? Commented Dec 14, 2022 at 4:54

1 Answer 1


Your Interlock plan sounds fine.

You can only power one panel from the generator, but that's all you're trying to do.

The neutral-ground bond on the generator will need to be disconnected. There can be only one system neutral-ground bond.

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