Which test assesses whether insulation resistance is sufficiently high?

• A. Continuity Test
• B. Dielectric Breakdown Test
• C. Dielectric Withstanding Test
• D. Insulation Resistance Test

Answer: (C)

The test that directly checks how well insulation resists leakage is the insulation resistance test. It uses a megohmmeter to apply a DC voltage between conductors (or between conductors and ground) and measures the resistance in megohms. A high resistance reading means little leakage current and good insulation; a low reading signals leakage paths due to moisture, contamination, or damage, indicating insulation isn’t sufficient. This is different from a continuity test, which only confirms a complete conductive path, and from dielectric breakdown or dielectric withstanding tests, which stress insulation with high voltage to see if it fails, rather than measuring its resistance.