Which Code reference specifies the type of disconnecting means that can be used on a multiwire branch circuit that feeds devices mounted on the same yoke?

Which Code reference specifies the type of disconnecting means that can be used on a multiwire branch circuit that feeds devices mounted on the same yoke?

• A. 210.12(B)(4)
• B. 300.5
• C. 240.15(B)(1)
• D. 110.3(B)

Answer: (C)

The key idea here is that a multiwire branch circuit uses two ungrounded conductors that share a neutral, and if those conductors feed devices on the same yoke, they must be able to be shut off together. The safety concern is that leaving one hot energized while the other is disconnected can still energize parts of the circuit or create shock hazards through the shared neutral or through the devices themselves. To prevent this, the disconnecting means must simultaneously disconnect all ungrounded conductors at the origin. In practice, that means using a common disconnect such as a two‑pole breaker with a common trip or a pair of breakers with a handle tie, so both hot conductors are opened together. The other options don’t address this requirement: they deal with unrelated topics like general listing/installation, wiring spacing, or AFCI protection. So the correct reference is the one that mandates a common, simultaneous disconnection of all ungrounded conductors for a multiwire branch circuit feeding devices on the same yoke.

The key idea here is that a multiwire branch circuit uses two ungrounded conductors that share a neutral, and if those conductors feed devices on the same yoke, they must be able to be shut off together. The safety concern is that leaving one hot energized while the other is disconnected can still energize parts of the circuit or create shock hazards through the shared neutral or through the devices themselves. To prevent this, the disconnecting means must simultaneously disconnect all ungrounded conductors at the origin. In practice, that means using a common disconnect such as a two‑pole breaker with a common trip or a pair of breakers with a handle tie, so both hot conductors are opened together. The other options don’t address this requirement: they deal with unrelated topics like general listing/installation, wiring spacing, or AFCI protection. So the correct reference is the one that mandates a common, simultaneous disconnection of all ungrounded conductors for a multiwire branch circuit feeding devices on the same yoke.