Originally Posted by Code05
210.4(C) Line-to-Neutral Loads. Multiwire branch circuits
shall supply only line-to-neutral loads.
Exception No. 1: A multiwire branch circuit that supplies
only one utilization equipment.
That provision allows a MWBC to supply a 240V load under that circumstance (e.g. a 120/240V dryer or stove), but it does not override the requirement in 240.15(B) that the OCPD open all poles automatically:
(B) Circuit Breaker as Overcurrent Device. Circuit
breakers shall open all ungrounded conductors of the circuit
both manually and automatically unless otherwise permitted
in 240.15(B)(1), (B)(2), (B)(3), and (B)(4).
Paragraph 1 under that creates an exception allowing handle ties for MWBC's that supply no 2-pole loads:
(1) Multiwire Branch Circuits. Individual single-pole circuit
breakers, with identified handle ties, shall be permitted
as the protection for each ungrounded conductor of multiwire
branch circuits that serve only single-phase line-to neutral