Iwire & gentlemen:
Your reference to 210.4 (b) is for residential.....not comm or industrial.
IMHO, a multi-wire circuit should be on a common trip breaker, multi pole, or handle ties. This practice can prevent an incident or accident down the road.
It may not be "Code required" but it can be installed, and it may be in the job specs. If it's in the specs/design/prints, then it can be enforced by the AHJ.
John
