What is the purpose of a multiwire branch circuit?

The purpose of a multiwire branch circuit is fundamentally about ensuring the simultaneous disconnection of all ungrounded conductors. This is significant for safety reasons in electrical systems. With a multiwire branch circuit, multiple circuits share one or more conductors (typically the neutral wire), which helps save on wiring costs and installation space. In doing so, it is crucial that all ungrounded conductors are disconnected together during maintenance or fault conditions to prevent electrical shock hazards or equipment failure. This simultaneous disconnection is achieved through the use of a double-pole circuit breaker that controls both ungrounded conductors at once.

While there are other characteristics of multiwire branch circuits, such as their ability to support certain types of loads or configurations, the primary focus is on safety and code requirements surrounding the disconnection of ungrounded conductors. This is why the correct answer emphasizes this aspect of the multiwire branch circuit's function.