Meters and troubleshootingQuestion 306 of 1506

You test a step-down control transformer with the power off. Which result is a good reading from the primary winding to the secondary winding?

  1. No continuity
  2. Near zero ohms
  3. About the same as the primary coil
  4. Full supply voltage
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Correct answer: No continuity

The windings are isolated from each other. Continuity between them means the insulation has failed.

Source: Troubleshooting Motors and Controls (Dickson-Self), 1.2: Electrical Fundamentals

Practice meters and troubleshooting

Questions last reviewed: 18 October 2026