The typical service voltage for one- and two-family dwellings is

The typical service voltage for one- and two-family dwellings is

• A. 120/240-volt, single-phase, three-wire
• B. 120/240-volt, three-phase, three-wire
• C. 120/208-volt, three-phase, four-wire
• D. 277/480-volt, three-phase, four-wire

Answer: (A)

Residential service uses a split-phase arrangement. A single-phase center-tapped transformer provides two hot legs that are 180 degrees out of phase plus a neutral. This gives 120 V from either hot leg to neutral for standard outlets and lighting, and 240 V between the two hot legs for higher‑voltage appliances. That setup is described as 120/240-volt, single-phase, three-wire. The other voltages shown reflect three-phase systems or higher-voltage distributions used in commercial or industrial settings, not typical for one- or two-family homes.

Residential service uses a split-phase arrangement. A single-phase center-tapped transformer provides two hot legs that are 180 degrees out of phase plus a neutral. This gives 120 V from either hot leg to neutral for standard outlets and lighting, and 240 V between the two hot legs for higher‑voltage appliances. That setup is described as 120/240-volt, single-phase, three-wire. The other voltages shown reflect three-phase systems or higher-voltage distributions used in commercial or industrial settings, not typical for one- or two-family homes.