A multiwire branch circuit from a 120/240-volt 1Ø, 3-wire panelboard will be used to supply power to a double single-pole switch. The NEC® requires that a multiwire branch circuit supplying more than one device or equipment on the same yoke have a means to simultaneously disconnect all ungrounded conductors at the panelboard where the branch circuit originated. This means that ___ can be used to disconnect the circuits from the receptacle.

A multiwire branch circuit from a 120/240-volt 1Ø, 3-wire panelboard will be used to supply power to a double single-pole switch. The NEC® requires that a multiwire branch circuit supplying more than one device or equipment on the same yoke have a means to simultaneously disconnect all ungrounded conductors at the panelboard where the branch circuit originated. This means that ___ can be used to disconnect the circuits from the receptacle.

• A. two single-pole circuit breakers
• B. one two-pole circuit breaker
• C. either a or b
• D. neither a nor b

Answer: (B)

When a multiwire branch circuit uses two hot conductors sharing a neutral, both ungrounded conductors must be disconnected at the same time from the panel where the circuit originates. A single two-pole breaker provides a common-trip mechanism, so flipping the switch breaks both hot legs simultaneously. That guarantees the required simultaneous disconnection with one device. Two separate single-pole breakers would only meet the requirement if their handles are tied or they’re a listed common-trip pair; otherwise they might not disconnect together. So the most reliable and straightforward option is a single two-pole circuit breaker.

When a multiwire branch circuit uses two hot conductors sharing a neutral, both ungrounded conductors must be disconnected at the same time from the panel where the circuit originates. A single two-pole breaker provides a common-trip mechanism, so flipping the switch breaks both hot legs simultaneously. That guarantees the required simultaneous disconnection with one device. Two separate single-pole breakers would only meet the requirement if their handles are tied or they’re a listed common-trip pair; otherwise they might not disconnect together. So the most reliable and straightforward option is a single two-pole circuit breaker.