Important terms/topics covered in this chapter: 

■ Ambient temperature The temperature of the air or other medium where the equipment is to be used

■ Circuit protective conductor A protective conductor connecting exposed conductive parts of equipment to the main earthing terminal

■ Current-carrying capacity The maximum current which can be carried by a conductor under specified conditions without its steady state temperature exceeding a specified value

■ Design current The magnitude of the current intended to be carried by a circuit in normal service

■ Earthing conductor A protective conductor connecting a main earthing terminal of an installation to an earth electrode or other means of earthing

■ Fault current An overcurrent resulting from a fault of negligible impedance between live conductors (short-circuit current) or between a line conductor and earth (earth fault current)

■ Overcurrent A current exceeding the rated value. For conductors the rated value is the current-carrying capacity