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Generator sub panel


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I inspected a sub panel that contained only the circuits that were being back fed from a generator. The only wiresw that terminated in this sub panel were the hot conductors. The grounds and neutrals remained in the main panel. Is this the correct way to do it?

I called it out as a problem and now they have a sparky telling me that I am wrong. That's fine, I have been wrong before.

The only thing I can find to support my opinion is:

E3306.7, which basically says all conductors of the circuit needs to be in the same raceway, cable, or cord. That may be what was stuck in my head why all wires should terminate in the same panel.

I have no problem telling the customer that I was wrong but I don't want to just take the sparkies word for it. Of course no permits were pulled from this subpanel.

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If your description is accurate, that sparky is a twit. Stand your ground.

The intent of E3306.6 is to provide for the cancellation of magnetic fields generated by the alternating current, otherwise small scale inductive heating of nearby conductive materials can result.


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There is a transfer switch of sorts. There are two double breakers connected by an pivoting lever. one breaker is fed with power from the generator and the other is fed from the main panel. So to circuits that are powered by this sub panel can only be powered by the power company or the generator not both at the same time.

I have never seen a set up like this before.

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Check out this page and download the pdf for the installation directions. It shows one green and one white from the transfer switch to the main panel from the generator switch.


Dedicated transfer switch panels like this are different than a sub panel rigged for a generator.

If it is a sub panel, then as Marc said, electrical code requires all circuit wire routed together. I also agree with the Twit assessment. Likely the sparky saying there is nothing wrong with it is the same one that installed it that way.

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