Creepage and Clearance

High voltage circuits can discharge across a gap, the gap can be through the air or across a surface.

  • Creepage: distance between two conductors on the surface.
  • Clearance: the distance between two conductors through the air.
schematic of creepage and clearance in HV systems

Hence, often just called creepage and clearance.

Factors affecting the minimum distance:

  • Input voltage
  • Insulation
  • Material group
  • Pollution degree
  • Overvoltage category
  • Altitude