Creepage distance is defined as...

• A. The length of the surface path along the insulator between two conductive points that must withstand voltage under polluted conditions.
• B. The maximum physical distance between conductor and ground.
• C. The distance through air between two conductive points.
• D. The depth of the insulator's material.

Answer: (A)

Creepage distance is the length of the path along the surface of an insulator between two conductive points that must withstand voltage under polluted conditions. This surface route matters because moisture and contaminants on the insulator surface can form a conductive film, making leakage and tracking travel along the surface rather than through the air. By designing a longer creepage path, you reduce the risk of surface arcing and improve insulation under polluted conditions.

This is different from clearance, which is the shortest straight-line distance through air between conductors; the body of the insulator material or its depth is not what creepage measures.