Three-phase circuits can be used for single-phase loads. True or false?

• A. Yes, they can be used for single-phase loads.
• B. No, they cannot be used for single-phase loads.
• C. They always require more conductor weight than single-phase.
• D. They never supply single-phase loads.

Answer: (A)

Three-phase sources can indeed power single-phase loads by tapping one phase to neutral. In a wye-connected system that has a neutral, the voltage from any one phase to neutral provides a standard single-phase voltage (for example, 120 V or 277 V, depending on the system). So a single-phase load can be connected between a single phase and the neutral while the other two phases continue delivering power for other loads. If the system lacks a neutral, you’d derive a usable single-phase supply via a transformer, but the basic idea remains: you can obtain single-phase power from a three-phase source.