Motor controlsQuestion 114 of 1506

What is a mechanical interlock on two contactors?

  1. A wire tie that holds the two coils together as one unit
  2. A relay in the reverse rung that opens the forward rung
  3. A lever joining the two armatures so they cannot close together
  4. A time-delay relay in each coil rung that holds them apart
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Correct answer: A lever joining the two armatures so they cannot close together

Electrical interlocks should still be used for extra safety.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 6.3: Permissive and Interlock Circuits

Practice motor controls

Questions last reviewed: 18 October 2026