In polluted environments, which factor most commonly reduces insulation performance?

• A. Increased surface conductivity from contaminants
• B. Decreased surface conductivity from contaminants
• C. Increased core insulation resistance
• D. Lower ambient humidity

Answer: (A)

Pollution on an insulator’s surface creates a thin, conductive film that lowers the surface resistance. This makes leakage current flow more easily along the surface, weakening the insulation where it’s most vulnerable and raising the risk of surface flashover in polluted environments. The core issue is the surface conductivity increase due to contaminants, which is why this option best explains the reduced insulation performance. Decreasing surface conductivity would improve insulation, increasing core insulation resistance isn’t the typical driver of pollution-related loss, and lower ambient humidity would generally reduce leakage rather than cause the reduction.