Which statement about single-phase AC power is true?

Which statement about single-phase AC power is true?

• A. 115 VAC is common for residential and multifamily applications
• B. 208 V or 230 V is common for residential
• C. 3-phase power cannot be used for gate operators
• D. 460 V is standard in homes

Answer: (A)

In residential single-phase power in the United States, the voltage is typically around 120 V, with 115 VAC still commonly cited on older equipment and literature. That’s why the statement that 115 VAC is common for residential and multifamily applications is the best fit. In practice, devices today are designed for about 120 V, so 115 V remains a familiar nominal value. The other voltages aren’t standard for typical home service: 208 V or 230 V shows up in other contexts (208 V from a 120/208 three-phase system or 230 V in many regions outside the US), but not as the usual residential single-phase supply in US homes. 460 V is a high industrial voltage, not used in homes. Gate operators can be powered from standard single-phase 120/240 V or from higher-voltage three-phase supplies with appropriate equipment, but the common residential single-phase reference remains around 115–120 V.

In residential single-phase power in the United States, the voltage is typically around 120 V, with 115 VAC still commonly cited on older equipment and literature. That’s why the statement that 115 VAC is common for residential and multifamily applications is the best fit. In practice, devices today are designed for about 120 V, so 115 V remains a familiar nominal value. The other voltages aren’t standard for typical home service: 208 V or 230 V shows up in other contexts (208 V from a 120/208 three-phase system or 230 V in many regions outside the US), but not as the usual residential single-phase supply in US homes. 460 V is a high industrial voltage, not used in homes. Gate operators can be powered from standard single-phase 120/240 V or from higher-voltage three-phase supplies with appropriate equipment, but the common residential single-phase reference remains around 115–120 V.