Red Seal Electrician Practice
AC theoryQuestion 917 of 1506

Which AC measurement is the most useful when rating insulators for a high-voltage AC service?

  1. Peak voltage
  2. RMS current
  3. Average current
  4. RMS power
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Correct answer: Peak voltage

Brief spikes of voltage can cause flashover, so the peak value matters.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 1.3: Measurements of AC Magnitude

Practice ac theory

Questions last reviewed: 18 October 2026