Red Seal Electrician Practice
Motor controlsQuestion 101 of 1506

The control wire between a switch and a lamp rubs against grounded conduit. The switch is on the hot side and the lamp is next to the grounded conductor. What happens?

  1. The lamp stays on with the switch open, and the fuse stays intact
  2. The lamp lights dimly at all times, because of a leakage path
  3. The lamp is shorted out, and closing the switch blows the fuse
  4. Nothing happens, and the lamp works normally from the switch
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Correct answer: The lamp is shorted out, and closing the switch blows the fuse

In this layout the ground fault is a fail-safe event.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 6.1: “Ladder” Diagrams

Practice motor controls

Questions last reviewed: 18 October 2026