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The Inspector's Journal

Transfer switch kosher?


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Never seen one of these before, Square D QO service and sub panels original to the house (1997). The service panel is nearly full, and the circuits designed for backup power are installed in the sub. The lever thingy turns off one source when the other is activated.

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tn_201232417715_XFER_SWITCH.jpg

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This by far the cleanest transfer arrangement I've ever seen, puts the Generac dreadlocs to shame, but I'm concerned that the breakers backfeeding this panel aren't secured and the lever thingy just clips on. Seems to me that it would be very easy to accidentally (or intentionally) close both switches, or remove a breaker while it's under load.

Is this cool or should it be fixed?

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I'd limit my comments to securing the backfed breakers.

The lever can't be removed without first removing the deadfront. As long as it's in place, you shouldn't be able to close both switches.

As for removing a breaker while under load, how would this be different from any other panel?

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Should the neutrals and grounding conductors not be separated? It is a subpanel. I would get it checked out.

Yes. You're right. Since, in this case, the neutral is not switched, the generator is not considered a separately derived system and the the ground/neutral connection should only be present at the service panel (or before it).

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Should the neutrals and grounding conductors not be separated? It is a subpanel. I would get it checked out.

Yes. You're right. Since, in this case, the neutral is not switched, the generator is not considered a separately derived system and the the ground/neutral connection should only be present at the service panel (or before it).

Aside from adding an equipment ground bar to this subpanel, the bonding jumper must also be removed inside the generator, otherwise you will still have the problem of a connection between the neutrals and equipment grounds past the service.

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Should the neutrals and grounding conductors not be separated? It is a subpanel. I would get it checked out.

Yes. You're right. Since, in this case, the neutral is not switched, the generator is not considered a separately derived system and the the ground/neutral connection should only be present at the service panel (or before it).

Aside from adding an equipment ground bar to this subpanel, the bonding jumper must also be removed inside the generator, otherwise you will still have the problem of a connection between the neutrals and equipment grounds past the service.

I've seen generators with and without bonding jumpers. Without looking at the schematic or opening up the generator, there doesn't seem to be a way to tell which is which. Any hints as far as that goes? Would testing for continuity between the EGC and the neutral tell us anything when the generator is off?

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