Creepage distance or creepage - the shortest distance along the surface of a solid insulating material between two conductive parts, with narrow grooves bridged accordingly to the level of surface contamination. Creepage is defined in such safety standards as IEC 61010.¹⁾

Example of creepage distance as per IEC 61010-1²⁾

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Creepage distance is an important concept for electrical safety, because it is used for defining internationally accepted limits for spacing to hazardous live conductors, so that appropriate level fo safety for the operator of the electrical equipment is maintained, as well as for reliability reasons (no sparking between conductors). Creepage is related to clearance, which is another critical safety parameter.

For a given design of an insulation system, the creepage distance is measured on the surface of the insulation, along the shortest possible path, and such that any grooves narrower than the distance X (Table 1) are bridged in a straight line.

Actual required distance is dictated by the amount of voltage expected between the conductors, air pressure, pollution, and also other factors. The specification for actual values (equations and tables) are prescribed in the standard IEC 61010.⁴⁾ The concept of creepage is used in many safety-related standards, such as IEC 60601-1⁵⁾.

Electric tracking occurs because of carbonisation, and carbon is included in all organic materials. As a consequence, according to IEC 61010, for inorganic insulating materials (which do not contain carbon) there are no requirements for creepage distances (but clearance still applies).⁶⁾

• Clearance distance