A megger insulation resistance test is used to assess insulation integrity by applying a high DC voltage between conductors and earth to measure resistance.

A megger insulation resistance test is used to assess insulation integrity by applying a high DC voltage between conductors and earth to measure resistance.

• A. Apply a high DC voltage between conductors and earth and measure insulation resistance to detect deterioration or faults.
• B. Measure insulation resistance by applying AC voltage.
• C. Check continuity of conductors under normal voltage.
• D. Verify insulation color coding on cables.

Answer: (A)

A megger insulation resistance test applies a high DC voltage between conductors and earth to measure insulation resistance. The aim is to push leakage paths through any deteriorated or moist insulation so you can quantify how well the insulation is holding up. A healthy insulation presents a very high resistance (large reading in megaohms); when insulation is compromised, moisture, cracks, or contaminants create leakage paths and the resistance drops, signaling faults that could lead to failure. This DC, high-voltage approach is chosen because it reveals long-term leakage tendencies and insulation integrity more clearly than AC methods or simple continuity checks. It’s not about checking conductor continuity at normal voltage, nor about verifying color coding—those have different purposes and tests.

A megger insulation resistance test applies a high DC voltage between conductors and earth to measure insulation resistance. The aim is to push leakage paths through any deteriorated or moist insulation so you can quantify how well the insulation is holding up. A healthy insulation presents a very high resistance (large reading in megaohms); when insulation is compromised, moisture, cracks, or contaminants create leakage paths and the resistance drops, signaling faults that could lead to failure. This DC, high-voltage approach is chosen because it reveals long-term leakage tendencies and insulation integrity more clearly than AC methods or simple continuity checks. It’s not about checking conductor continuity at normal voltage, nor about verifying color coding—those have different purposes and tests.