In a 480Y/277 V system, what is the voltage between any phase and neutral?

In a 480Y/277 V system, what is the voltage between any phase and neutral?

• A. 277
• B. 0
• C. 120
• D. 480

Answer: (A)

In a 480Y/277 V system, the three phases form a wye with a neutral. The line-to-line voltage is 480 V, and in a wye connection the line-to-neutral voltage is the line-to-line voltage divided by √3. So 480 ÷ √3 ≈ 277 V. That’s why the voltage between any phase and neutral is about 277 V. The other options don’t fit this relationship: 480 V is the voltage between two phases, not phase-to-neutral; 0 V would imply no difference; 120 V corresponds to a different system (such as 208Y/120).

In a 480Y/277 V system, the three phases form a wye with a neutral. The line-to-line voltage is 480 V, and in a wye connection the line-to-neutral voltage is the line-to-line voltage divided by √3. So 480 ÷ √3 ≈ 277 V. That’s why the voltage between any phase and neutral is about 277 V. The other options don’t fit this relationship: 480 V is the voltage between two phases, not phase-to-neutral; 0 V would imply no difference; 120 V corresponds to a different system (such as 208Y/120).