What is required when connecting a multiwire branch circuit to a duplex receptacle with a common neutral conductor?

When using a multiwire branch circuit with a common neutral conductor connected to a duplex receptacle, it is essential to ensure that all ungrounded conductors (the hot wires) can be disconnected simultaneously. This requirement is in place to safeguard both the wiring system and individuals from potential electric shock or fire hazards. If the ungrounded conductors are not disconnected at the same time, there could be a situation where one part of the circuit remains live while the other part is worked on, leading to dangerous conditions.

Utilizing a means to disconnect all ungrounded conductors simultaneously ensures that, during maintenance or when servicing the receptacle, the circuit is entirely de-energized. This practice is not only a safety measure but also aligns with the electrical code requirements that govern multiwire branch circuits.

The other options may represent good practices or safety measures in general wiring techniques, but they do not specifically address the fundamental safety requirement that is crucial for multiwire circuits connected to a receptacle with a shared neutral. Thus, the answer reflects the core necessity for safety when dealing with such configurations in electrical installations.