Ampacity - an introduction

Ampacity or 'ampere-carrying capacity' refers to the ability of a conductor such as wires, cables or busbars to carry current without getting damaged due to overheating.

The ampacity of a conductor should be optimimum with respect to the application. A lower ampacity would result in heating and damage to the insulation. An excessive ampacity selection would result in unnecessarily high costs.

The ampacity of any conductor depends on the following factors.
  • The temperature rating of its insulation or the insulation class.
  • The electrical properties of the conductor such as resistivity, etc.
  • The heat dissipating capacity of the conductor; this depends on the shape of the conductor, the conductor location and ambient temperature, etc.