30 - Properties and Ratings of Current-carrying Conductors

Abstract

This chapter discusses the properties and current ratings for aluminum and copper conductors. It describes the physical, mechanical, and electrical properties of metal that are important for conduction of current. A metal used for the purpose of current carrying must be checked for its conductivity. This is proportional to its current-carrying capacity. The electrical conductivity of a metal is reciprocal to its resistivity. Size and rating recommendations for copper and aluminum conductors are provided in this chapter. Thinner sections of metal \\have a relatively higher surface area to dissipate heat compared to thicker sections. The thinner the section, the better will be metal utilization and vice versa. More bars will reduce the heat dissipation further and will require yet higher deratings. The thinner the surface, the smaller will be the nucleus resulting in a higher concentration of current at the surface and better utilization of metal. These factors must be taken into account while deciding on the most appropriate and economical sections of the metal conductors for the required current rating.