How can three wire circuits be distinguished?

Three-wire circuits can be distinguished primarily by the configuration of their wiring and the presence or absence of certain components. In this case, option B is correct because it describes a scenario where there is a lack of a neutral wire and the transformers are connected phase to phase.

In three-wire systems, especially in electric power distribution, two phases are typically utilized without a dedicated neutral wire. This configuration allows for the operation of three-phase equipment using the two phases, creating a balanced load. The fact that transformers are connected phase to phase is also significant because it enables the utilization of the phase-to-phase voltage for certain applications, which is higher than the phase-to-neutral voltage found in more traditional systems.

Understanding this setup is crucial, as it shapes the performance, efficiency, and safety considerations inherent in three-wire circuits compared to other configurations that might involve neutral wires or different transformer connections.