What is a three-phase three-wire system referred to as?

• A. Wye
• B. Open delta
• C. Delta
• D. Balanced delta

Answer: (C)

A three-phase three-wire setup is a delta connection. In a delta, the three windings are connected in a closed loop, forming a triangle, and three conductors carry the three phase currents with no neutral conductor. That absence of a neutral is what makes it a three-wire system.

If you used a Wye (star) arrangement, you’d have a neutral and three hot conductors plus that neutral, making four wires total. Open delta is a delta variant that uses a different transformer arrangement but still involves three lines, and balanced delta describes a condition where the voltages are equal, not a distinct wiring scheme.