Red Seal Electrician Practice
Motor controlsQuestion 81 of 1506

What is the auxiliary contact of a motor contactor used for?

  1. Carrying the motor current for one phase while the motor is running at speed
  2. Cooling the overload heater when the motor is stopped for a while
  3. Switching control circuit signals, such as 120 V AC, for seal-in or interlocks
  4. Providing a ground path for the motor frame during a ground fault
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Correct answer: Switching control circuit signals, such as 120 V AC, for seal-in or interlocks

It has a much lower current rating than the power contacts but moves with the same armature.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 5.2: Contactors

Practice motor controls

Questions last reviewed: 18 October 2026