In a three-phase system, the line-to-neutral voltage on a 208V system is which value?

In a three-phase system, the line-to-neutral voltage on a 208V system is which value?

• A. 120V
• B. 104V
• C. 208V
• D. 52V

Answer: (A)

In a three-phase system wired in wye, the line-to-line voltage is sqrt(3) times the line-to-neutral voltage. Here, the line-to-line value is 208 V, so the line-to-neutral (phase) voltage is 208 divided by sqrt(3). Using sqrt(3) ≈ 1.732, that gives 208 / 1.732 ≈ 120 V. So the line-to-neutral voltage is 120 V. This is why a common 120/208 V system uses 120 V to neutral and 208 V between any two phases.

In a three-phase system wired in wye, the line-to-line voltage is sqrt(3) times the line-to-neutral voltage. Here, the line-to-line value is 208 V, so the line-to-neutral (phase) voltage is 208 divided by sqrt(3). Using sqrt(3) ≈ 1.732, that gives 208 / 1.732 ≈ 120 V. So the line-to-neutral voltage is 120 V. This is why a common 120/208 V system uses 120 V to neutral and 208 V between any two phases.