main breaker and upstream breaker

[papa smurf]

If a building has a panel with a 200 amp breaker but the feed is only a 1/0 copper, but the distrubution upstream breaker is 100 amps. The distrubution is located outside away from the building but I talked to an electrical engineer and he said this was leagal and the code didnt really specifiy that the interior panel had to have the exact size breaker as the upstream breaker. He said that just as long as the wire was sized according to the upstream breaker and the interior would be just a disconnect. Is this correct.

 

[charlie b]

I wouldn't choose to do it that way, but I think it is code compliant. The interior panel does not need a breaker at all. The building needs a disconnecting means, and a breaker in the interior panel can serve that need. But so too could an unfused disconnect switch.

 

[augie47]

Everthing sounded good until I read "away from the building". If this is the only feeder to the building and all other NEC regs are met (grounding) etc. I don't see where it is a violation.
Fairly common inside the same structure.

 

[Twoskinsoneman]

If a building has a panel with a 200 amp breaker but the feed is only a 1/0 copper, but the distrubution upstream breaker is 100 amps. The distrubution is located outside away from the building but I talked to an electrical engineer and he said this was leagal and the code didnt really specifiy that the interior panel had to have the exact size breaker as the upstream breaker. He said that just as long as the wire was sized according to the upstream breaker and the interior would be just a disconnect. Is this correct.

Nothing wrong with it. Guys correct me if I wrong but a building like that (possible an aux building) requires a disconnect near the point of entrance of feeder but it doesn't have to be a breaker. So too large a breaker not an issue...