What does a megger test indicate about insulation quality?

• A. High insulation resistance indicates good insulation and low leakage; low value shows deterioration or moisture.
• B. It measures the temperature of conductors.
• C. It determines color coding.
• D. It tests continuity.

Answer: (A)

Megger testing checks insulation resistance by applying a high DC voltage and measuring how much current leaks through the insulation. The key idea is that good insulation resists leakage, so you get a high insulation resistance value. If the insulation is deteriorated or moist, leakage increases and the resistance falls. So a high resistance means strong insulation with little leakage, while a low resistance points to moisture, degradation, or damage.

This test isn’t about temperature, color coding, or electrical continuity, which are covered by other tests and instruments.