If I have a 200 amp 240 volt 10,000 A.I.C. breaker enclosure feeding a 200 amp panel with a 200 amp main 22,000 A.I.C. and the panel contains breakers with a 10,000 A.I.C. would you be surprised if a ground fault on a 20 amp breaker tripped the main breaker in the panel as well as the 20 amp breaker?
Do I have a coordination problem?All breakers are Square D.
You MIGHT have a coordination problem, but it depends.
1) If your Available Fault Current is between 10kA and 22kA, then the first panel is illegal.
2) If your AFC is below 10kA, someone wasted money on panel #2 but that is not illegal.
In either case it will
not make any difference whatsoever in the tripping coordination of the mains on those panels, they would be the same. AIC ratings have nothing to to with trip coordination in all but certain special cases*. So what Jim Dungar said is much more likely. And by the way, I would highly suspect that the GF happened BETWEEN the 20A CB and the GFCI receptacle because if it happened down stream of the GFCI receptacle I would expect that would trip faster than either breaker. Not guaranteed, but much more likely.
* Sometimes when you get into larger systems with series rated devices a difference in a device used in series may end up being a different trip curve. But I would be highly surprised if a 200A MCB on a 10kA panel and the same one on a 22kA panel have different trip curves. In fact more than likely they are the exact same breaker with a different sticker on it (and a higher price for the priviledge).