In a 480 V three-phase system, the line-to-line voltage is

In a 480 V three-phase system, the line-to-line voltage is

• A. 120
• B. 208
• C. 277
• D. 480

Answer: (D)

In three-phase systems, the rating is typically the line-to-line voltage. So describing a system as 480 V three-phase means the voltage between any two of the three conductors is 480 V. If that system is a wye (star) configuration, the line-to-neutral voltage would be 480 divided by sqrt(3), about 277 V. That’s why 277 V appears as a related value, but it’s the line-to-neutral, not the line-to-line. Other numbers come from different systems: 208 V is the line-to-line voltage for a 120/208 V system, and 120 V is the line-to-neutral for that same setup. In a 480 V delta system there’s no neutral, but the line-to-line remains 480 V. Therefore, the line-to-line voltage is 480 V.

In three-phase systems, the rating is typically the line-to-line voltage. So describing a system as 480 V three-phase means the voltage between any two of the three conductors is 480 V. If that system is a wye (star) configuration, the line-to-neutral voltage would be 480 divided by sqrt(3), about 277 V. That’s why 277 V appears as a related value, but it’s the line-to-neutral, not the line-to-line. Other numbers come from different systems: 208 V is the line-to-line voltage for a 120/208 V system, and 120 V is the line-to-neutral for that same setup. In a 480 V delta system there’s no neutral, but the line-to-line remains 480 V. Therefore, the line-to-line voltage is 480 V.