Red Seal Electrician Practice
Power factor and three-phaseQuestion 1002 of 1506

A 12 kW resistive load is supplied at 120 V, then at 240 V. How does the supply current change?

  1. It doubles at 240 V
  2. It is cut in half at 240 V
  3. It stays the same
  4. It is cut to one quarter at 240 V
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Correct answer: It is cut in half at 240 V

For the same power, I = P/E. Doubling the voltage halves the current, so smaller conductors can be used.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 7.1: Single-Phase Power Systems

Practice power factor and three-phase

Questions last reviewed: 18 October 2026