Each multiwire branch circuit shall have a means to simultaneously disconnect all _____ conductors at the point where the branch circuit begins.

In the context of multiwire branch circuits, the requirement for a means to simultaneously disconnect all ungrounded conductors is critical for safety and compliance with electrical codes. Multiwire branch circuits typically consist of two or more ungrounded conductors that share a common neutral. This arrangement can create potential hazards if all conductors are not properly disconnected simultaneously when servicing or working on the circuit.

The necessity for disconnecting all ungrounded conductors helps to prevent scenarios where one part of the circuit remains energized while another part is being worked on. By ensuring that all ungrounded conductors are disconnected simultaneously, it reduces the risk of electric shock or arc flash incidents for anyone who may be performing maintenance or troubleshooting on the system.

The other terms, such as grounded, unshielded, and isolated, do not apply directly to the requirement for simultaneous disconnection of conductors in multiwire branch circuits. Grounded conductors are typically connected to earth ground and do not pose the same risk when working on them. Unshielded refers to a type of wiring insulation or construction that does not have a protective shield and is not relevant to disconnecting practices. "Isolated" may relate to other electrical concepts but does not specifically address the requirement of simultaneous dis