When checking insulation resistance, the motor should be turned off.

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Multiple Choice

When checking insulation resistance, the motor should be turned off.

Explanation:
Insulation resistance is measured with the equipment de-energized so the test meter can evaluate the winding insulation alone, without any live electrical paths. When the motor is running or connected to power, leakage currents flow through the supply, switchgear, and other connected components, and possibly move parts, which contaminates the reading and can even damage the tester. By turning the motor off and isolating it, you ensure the measurement reflects the true resistance of the insulation to ground or between windings. This is why the proper procedure requires the motor to be off rather than running, idle with power, or unloaded, even though those states might seem harmless.

Insulation resistance is measured with the equipment de-energized so the test meter can evaluate the winding insulation alone, without any live electrical paths. When the motor is running or connected to power, leakage currents flow through the supply, switchgear, and other connected components, and possibly move parts, which contaminates the reading and can even damage the tester. By turning the motor off and isolating it, you ensure the measurement reflects the true resistance of the insulation to ground or between windings. This is why the proper procedure requires the motor to be off rather than running, idle with power, or unloaded, even though those states might seem harmless.

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