How does moisture ingress affect insulator performance?

• A. Lowers surface resistance and increases leakage current.
• B. Increases mechanical strength and thermal stability.
• C. Creates a protective hydrophobic layer improving insulation.
• D. Eliminates the risk of surface flashover.

Answer: (A)

Moisture ingress changes the insulator’s electrical behavior by forming a thin conductive path on its surface. This lowers the surface resistance, so more current can leak along the surface under voltage, i.e., leakage current increases. In polluted or dusty environments, dissolved ions from the contaminants act as electrolytes, further reducing surface resistance and the dielectric strength, which raises the probability of surface flashover, especially during rain or high humidity. Moisture does not strengthen the insulator or create a protective layer; it actually degrades insulation performance and increases the risk of leakage and flashover.