After installation, which test verifies insulation condition between conductors and earth?

• A. Continuity test.
• B. Insulation resistance test (megohmmeter) and verify results meet acceptance values per spec.
• C. Hipot test.
• D. Ground resistance test.

Answer: (B)

Insulation resistance testing is used to verify insulation condition between conductors and earth. By applying a specified DC voltage with a megohmmeter and measuring the resistance, you can assess how well the insulation prevents leakage to the earth. A high resistance reading indicates good insulation, while a low reading points to moisture, contamination, or damaged insulation that could allow leakage current to flow to ground. This method directly checks the insulating barrier's effectiveness, which is why it’s the appropriate test after installation. Other tests don’t measure insulation quality in the same way: continuity testing checks for a complete electrical path, ground resistance testing evaluates the earth grounding system, and hipot tests assess dielectric strength under high voltage rather than leakage resistance. Always compare the results to the acceptance values specified for the system.