Red Seal Electrician Practice
Motor controlsQuestion 36 of 1506

The stop button is wired normally open to a PLC input, and the program uses a normally closed contact for it. A wire to that input breaks. What happens?

  1. The motor stops immediately
  2. The motor cannot be started
  3. The motor cannot be stopped from that button
  4. The PLC trips its supply breaker as soon as the wire breaks
Show answer

Correct answer: The motor cannot be stopped from that button

A broken wire looks like an unpressed stop button, so the stop signal is lost.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 6.6: Programmable Logic Controllers (PLC)

Practice motor controls

Questions last reviewed: 18 October 2026