What is insulation resistance testing and why is it performed?

What is insulation resistance testing and why is it performed?

• A. A test to measure conductor corrosion resistance.
• B. A test to verify wiring color coding.
• C. A Megger test used to verify the integrity of insulation and detect breakdown paths.
• D. A test to measure a capacitor's capacitance.

Answer: (C)

Insulation resistance testing checks how well insulation prevents current from leaking. This is done with a megohmmeter (Megger) that applies a high DC voltage to the conductors and insulation and measures the leakage resistance. The goal is to verify the insulation’s integrity and reveal any breakdown paths where current could flow to earth or between conductors. This matters because aging insulation, moisture, contamination, or physical damage create leakage paths that reduce resistance and can lead to shock, short circuits, or equipment failure at operating voltage. A high insulation resistance means the insulation is in good condition, while low resistance flags problems that need repair or replacement. It’s not about conductor corrosion, wiring color coding, or capacitor capacitance, which are different tests.

Insulation resistance testing checks how well insulation prevents current from leaking. This is done with a megohmmeter (Megger) that applies a high DC voltage to the conductors and insulation and measures the leakage resistance. The goal is to verify the insulation’s integrity and reveal any breakdown paths where current could flow to earth or between conductors. This matters because aging insulation, moisture, contamination, or physical damage create leakage paths that reduce resistance and can lead to shock, short circuits, or equipment failure at operating voltage. A high insulation resistance means the insulation is in good condition, while low resistance flags problems that need repair or replacement. It’s not about conductor corrosion, wiring color coding, or capacitor capacitance, which are different tests.