In a 240V-120V Delta system, the high leg is?

In a 240V-120V Delta system, the high leg is?

• A. 120V
• B. 208V
• C. 240V
• D. 480V

Answer: (B)

In this 240V delta with a center-tapped winding, two of the legs measure 120V to neutral, but the third leg to neutral is higher. The neutral sits at the center of one winding, and the three phase voltages are 120 degrees apart, which makes the voltage from the high leg to neutral about 120 × √3 ≈ 208V. That’s why the high leg is designated as the one with roughly 208V to neutral. The other two legs to neutral are 120V, while the line-to-line voltage remains 240V. The 208V value is what makes the high leg different from the others, and it’s why it isn’t used for 120V loads.

In this 240V delta with a center-tapped winding, two of the legs measure 120V to neutral, but the third leg to neutral is higher. The neutral sits at the center of one winding, and the three phase voltages are 120 degrees apart, which makes the voltage from the high leg to neutral about 120 × √3 ≈ 208V. That’s why the high leg is designated as the one with roughly 208V to neutral. The other two legs to neutral are 120V, while the line-to-line voltage remains 240V. The 208V value is what makes the high leg different from the others, and it’s why it isn’t used for 120V loads.