Red Seal Electrician Practice
Motor controlsQuestion 35 of 1506

In a PLC motor circuit, the stop push button is wired as normally closed and the program uses a normally open contact for that input. What is the benefit?

  1. A broken wire on the stop input stops the motor, which is fail-safe
  2. A broken wire on the stop input keeps the motor running, which is the safer result
  3. The stop button needs no wire to the PLC
  4. The input LED never lights
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Correct answer: A broken wire on the stop input stops the motor, which is fail-safe

An open wire acts like a pressed stop button.

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

Practice motor controls

Questions last reviewed: 18 October 2026