Clearance distance or clearance - the shortest “line of sight” distance in air between two conductive parts, as defined in such safety standards as IEC 61010.¹⁾

Example of a clearance distance as per IEC 61010-1²⁾

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Clearance 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). Clearance is related to creepage, which is another critical safety parameter.

For a given design of an insulation system, the clearance distance is measured in air along the shortest possible path of “line of sight”, as allowed by protrusions of solid insulation.

Actual required distance is dictated by the amount of voltage expected between the conductors, air pressure, pollution, and also other factors, as prescribed in the standard IEC 61010.³⁾ However, clearance is not affected by a pollution degree, whereas creepage is affected. The concept of clearance is used in many safety-related standards, such as IEC 60601-1⁴⁾

• Creepage distance