In insulation resistance testing, what does a low leakage resistance reading indicate?

• A. Good insulation
• B. Leakage or damage
• C. High insulation
• D. No fault

Answer: (B)

In insulation resistance testing, you’re looking at how well the insulation blocks DC current. A low resistance reading means there are leakage paths that let current flow, which points to leakage or damage in the insulation. This can come from moisture, dirt or chemical contamination, cracks or breakdown in the insulation, or worn coatings that allow conductive paths along surfaces. High resistance, by contrast, indicates the insulation is effectively blocking current and is in good condition. Temperature and moisture affect the readings—wet or humid conditions and higher temperatures tend to reduce resistance, while dry, clean conditions raise it. So a low reading signals leakage or damage rather than a fault-free, well-insulated condition.