Red Seal Electrician Practice
Wiring and componentsQuestion 617 of 1506

What is a double-insulated appliance?

  1. One with a nonconductive case that adds a second insulation layer
  2. One with two power cords that feed it from two separate circuits at once
  3. One with a metal case that is bonded to ground by a third prong
  4. One with a fuse on both the hot wire and the neutral wire
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Correct answer: One with a nonconductive case that adds a second insulation layer

The insulating case works as a second layer, so a loose wire touching it is no danger to the user.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 3.8: Safe Circuit Design

Practice wiring and components

Questions last reviewed: 18 October 2026