What is the common term for a circuit that uses both 120V and 240V?

The term "multi-wire branch circuit" is the correct terminology for a circuit that can utilize both 120V and 240V. In electrical systems, a multi-wire branch circuit connects multiple circuits that share a common neutral wire while drawing power from different phases of a power source. This arrangement allows the circuit to take advantage of both voltages, facilitating more efficient use of electrical resources.

Typically, in a residential setting, such circuits consist of two hot wires, each carrying 120V, that are connected to a split-phase service and share a neutral wire. This configuration can allow for different voltage outputs depending on how the loads are connected.

The other terms, while they might suggest a concept involving two different voltages, do not accurately describe this specific electrical arrangement. A hybrid circuit suggests a combination of different circuit types without indicating the specifics of voltage, while dual power circuit and combined voltage circuit are not standard terms used in electrical code or practice. Thus, "multi-wire branch circuit" is the precise term that captures the functionality and configuration of such circuits.