Red Seal Electrician Practice
Power factor and three-phaseQuestion 1013 of 1506

What is the advantage of a three-phase supply over a single-phase supply for the same power and load voltage?

  1. Higher conductor currents
  2. A lower power capacity for the same wire
  3. A higher voltage across each load
  4. Lower conductor currents, so thinner wire
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Correct answer: Lower conductor currents, so thinner wire

In the text example, 30 kW needs 83 A per conductor in three-phase and 250 A single-phase.

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