During a megger insulation test on a motor, the megger leads should be connected to the Start and Common terminals.

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Multiple Choice

During a megger insulation test on a motor, the megger leads should be connected to the Start and Common terminals.

Megger insulation testing is about measuring the resistance of insulation between conductive parts and the motor frame (or between windings) to ensure there’s no leakage path. Connecting the leads between Start and Common would place the test across the ends of the same winding, effectively measuring a copper path rather than insulation. That would give a meaningless or misleading result and not reflect the true insulation health of the motor. The correct approach is to test from winding terminals to the motor frame (and, if testing inter-winding insulation, between windings that are suitably isolated), with the motor fully disconnected from power and any capacitors discharged.

Megger insulation testing is about measuring the resistance of insulation between conductive parts and the motor frame (or between windings) to ensure there’s no leakage path. Connecting the leads between Start and Common would place the test across the ends of the same winding, effectively measuring a copper path rather than insulation. That would give a meaningless or misleading result and not reflect the true insulation health of the motor. The correct approach is to test from winding terminals to the motor frame (and, if testing inter-winding insulation, between windings that are suitably isolated), with the motor fully disconnected from power and any capacitors discharged.

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