Red Seal Electrician Practice
Wiring and componentsQuestion 809 of 1506

Two conductors have the same size and are both in free air. One has insulation with a higher temperature limit. What is the result?

  1. Both carry the same current because the copper is the same.
  2. Higher-temperature insulation allows more current.
  3. The lower-temperature insulation allows more current.
  4. The insulation type changes only the voltage rating, not the current.
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Correct answer: Higher-temperature insulation allows more current.

Ampacity follows the thermal limit of the insulation, so a higher limit allows more current in the same size of copper.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 12.3: Conductor Ampacity

Practice wiring and components

Questions last reviewed: 18 October 2026