What voltage should a meter indicate between phase A and phase C on a 240-volt delta system?

What voltage should a meter indicate between phase A and phase C on a 240-volt delta system?

• A. 0
• B. 240
• C. 120
• D. 480

Answer: (B)

In a 240-volt delta, the windings form a triangle and are each rated for 240 V across their ends. Measuring between any two phase conductors corresponds to the voltage across the winding between those two lines, so the reading between phase A and phase C is 240 volts. The neutral isn’t involved in a simple delta measurement, though a high-leg delta can provide 120 V to neutral for some loads; that doesn’t change the line-to-line voltage, which remains 240 V. The other numbers would not apply for a line-to-line measurement in this system.

In a 240-volt delta, the windings form a triangle and are each rated for 240 V across their ends. Measuring between any two phase conductors corresponds to the voltage across the winding between those two lines, so the reading between phase A and phase C is 240 volts. The neutral isn’t involved in a simple delta measurement, though a high-leg delta can provide 120 V to neutral for some loads; that doesn’t change the line-to-line voltage, which remains 240 V. The other numbers would not apply for a line-to-line measurement in this system.