In a 480Y/277 V system, the voltage from a phase conductor to neutral is

In a 480Y/277 V system, the voltage from a phase conductor to neutral is

• A. 0
• B. 277
• C. 480
• D. 120

Answer: (B)

In a 480Y/277 V system, the transformer secondary is connected in a wye (star). The neutral is the center point, so the voltage from a phase conductor to neutral is the line voltage divided by the square root of 3. That gives 480 V ÷ √3 ≈ 277 V. So the phase-to-neutral voltage is 277 V. The other options don’t fit this system: 0 V would be neutral-to-neutral, 480 V is the line-to-line voltage, and 120 V isn’t part of this 480Y/277 V arrangement.

In a 480Y/277 V system, the transformer secondary is connected in a wye (star). The neutral is the center point, so the voltage from a phase conductor to neutral is the line voltage divided by the square root of 3. That gives 480 V ÷ √3 ≈ 277 V. So the phase-to-neutral voltage is 277 V. The other options don’t fit this system: 0 V would be neutral-to-neutral, 480 V is the line-to-line voltage, and 120 V isn’t part of this 480Y/277 V arrangement.