Red Seal Electrician Practice
Power factor and three-phaseQuestion 1084 of 1506

For the same total power, how does the line current of a three-phase 120/208 V system compare with a split-phase 120/240 V system in the text example?

  1. Higher (125 A versus 83 A)
  2. The same (83 A in each)
  3. Lower (83 A versus 125 A)
  4. Half (62 A versus 125 A)
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Correct answer: Lower (83 A versus 125 A)

In the example, 30 kW takes 83 A per line in three-phase and 125 A per line in split-phase. The thinner wire is the saving.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 7.2: Three-phase Power Systems

Practice power factor and three-phase

Questions last reviewed: 18 October 2026