Thank you, you're not missing anything, I just wanted others input. This is the first time I've seen the frame rating not being equal to or less than the bus rating. I wasn't sure if the code is referring to the Frame or Trip rating. I imagined a case where someone looking to add more loads would see the max trip setting of the MCB could mistakenly assume that the bus could handle 250 A. Perhaps any qualified Electrician would never do that. But again, the bus is a conductor so it also makes sense that the trip setting is all that matters.
Thank you David, I didn't realize that adjustable breakers could be fixed permanently. I always thought they could be field adjusted.
That looks like a submittal from Square D. Because it says "STD LI" I think that's a JD circuit breaker with electronic trip and adjustable LI. The long-time pickup setting dial is not fixed permanently. It is a field adjustment dial that ranges up to 250A, as noted by the "250AS".
Thank you very much for the concise information. We'd fall into (C)(3). I appreciate everyone's input!
Great to know, thank you!