Section 210.4/Multiwire Branch Circuits
NEC 210.4 requires multiwire branch circuits to have simultaneous disconnection of all ungrounded conductors and limits where they can be used.
A multiwire branch circuit must have a means that simultaneously disconnects all ungrounded conductors at the point where the circuit originates. This requires either a multi-pole breaker or individual single-pole breakers with an approved handle tie. The ungrounded conductors must be connected to different phases so the shared neutral carries only the imbalance current.
Why this section exists
Multiwire branch circuits share a neutral conductor between two or three ungrounded conductors on different phases. If the ungrounded conductors are on the same phase, the neutral carries additive current rather than difference current, leading to overload. The simultaneous disconnect prevents a technician from turning off one breaker while the neutral remains energized from the other circuit, creating a shock hazard during maintenance.
What plan reviewers look for
Plan reviewers check that multiwire branch circuits on the panel schedule use multi-pole breakers or have handle ties noted. They verify that the circuits land on different phases (adjacent slots in a typical panel are on different phases) and that the neutral is not shared with circuits on the same phase.
Common violations
Related NEC requirements
Section 210.11(C)(3) requires dedicated bathroom circuits. Section 200.6covers neutral conductor identification, which is critical when multiple multiwire circuits are present. Section 408.4 requires panel schedule directories that should identify shared neutrals.