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Sub panel feeder tapped to main panel hot bus bar


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I recently looked at a 1983 home with a 400 amp main panel where the sub panel was fed by taps directly off the hot bus bar. It looks like the space was intended for taps, but this is the first time I've seen such a thing. The 4 wire feeder wire runs in a short conduit through the wall to the sub panel next to the main panel to a 200 amp main breaker at the sub panel.

The neutral and grounds are separated and every thing else is correct except for the the ground wires that are pig tailed together and then secured under a single lug which I'm going to note need repair.

Are taps on the main bus bar okay as long as there is over cut protection at the sub-panel? How would I determine if such an installation is okay? Manufacture label?

Thanks

Kiel

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Unless the sub cables are overcurrent/short circuit protected, it's wrong. I don't see how the sub-panel supply conductors could qualify as a tap. I don't see a handle on that component on the main panel where the sub cables connect but there might be something there that I don't know about. I've never seen that before.

Marc

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After reading 240.21 (B) (1), it seems that this tap could be legit. What's key is that it's a feeder, which is defined as any conductor between the SEC and the branch circuit protection device. There's a lot of allowance for taps if the tap conductors meet the definition of a feeder.

You won't find this info on the manufacturer's label.

Marc

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Looks to me like 100-amp wire protected by a 400-amp breaker. Is there possibly an exception allowed because it's only traveling a foot or so?

Agreed. I would have an electrician verify that it is kosher, because I believe it would not be allowed here, Canada.

The wire gauge needs to be rated for the breaker feeding it, 400 Amps.

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As Marc noted, this installation is specifically allowed by the 10-foot tap rule.

The feeder is fully protected at the sub panel breaker and it's protected against faults at the service panel breaker. The dedicated lugs are the key here, as is the conduit. You're not supposed to do this with improper lug connections and you're not supposed to do it with cable.

I wouldn't bother calling for an electrician for this aspect of the installation.

I'm curious, though, about the lug at the bottom left corner of photo 2566. It looks like a lug that's intended to hold two conductors. What's going on there?

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Thank you for the reply and clarification guys.

Jim, you're correct. That lug is for the main neutral and the neutral for the sub panel is also picked up off the same lug.

The equipment grounds in the sub panel were jacked up. They were all secured under a few lugs bonded to the panel which I guess works, but some were not connected at all, while others were pig tailed together with only few wires running to the equipment ground lugs.

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