What is the primary purpose of maintaining appropriate creepage paths in insulator design?

• A. To improve aesthetic appearance.
• B. To reduce surface conduction and prevent tracking under polluted conditions.
• C. To increase mechanical strength of the core.
• D. To shorten installation time.

Answer: (B)

The main idea is that creepage path length controls how much leakage current can travel along the surface of an insulator. In polluted or humid conditions, dirt and moisture form a conductive film on the surface. If the surface path between conductors (or between a conductor and ground) is too short, current can creep along that film, causing surface conduction and potentially tracking, which can lead to flashover. By ensuring the creepage distance is long enough, the surface resistance is higher and the likelihood of a continuous conductive path is reduced, preventing tracking under polluted conditions. This purpose is specific to surface behavior and reliability, not aesthetics, mechanical strength, or installation speed.