1.1 Introduction

The search for a good conductor of electricity began with the commercialization of power generation, transmission & distribution, and utilization. Good conductors were also required for the manufacture of associated power equipment.

Copper had long been identified as the ideal conductor of electricity, not only for power transmission and distribution but also for connected power equipment such as generators, transformers, motors, and switchgear. The metal was so much associated with the industry that any resistive loss in a conductor was termed copper-loss. International Annealed Copper Standard (IACS) established in 1914 had pegged the conductivity of pure Copper as 100% and the conductivity of all other metals & alloys is still expressed as a percentage of this standard conductivity. Interestingly, even today, many consumers are prepared to pay a premium to install Copper conductors for certain applications because of its perceived higher reliability.

With the increase in demand for power, it became imperative to search for an alternative material for the conductor to meet the demand and offer cost benefits. The volatility in the price of Copper hastened the need to find a substitute. Aluminium, an element that is abundantly available on the planet, had also been identified as a good conductor of electricity. In time, driven by cost considerations, Aluminium, with a conductivity of 55% to 62% of Copper was widely accepted as a replacement in overhead conductors, cables, switchgear panels, and Busbar Systems.

The ascension of Aluminium to the position of a conducting material did not happen overnight. Industry and consumers had been reluctant to use Aluminium as a conductor, based on their experience and feedback from the building industry. There were failures due to overheating, which in some cases, resulted in the outbreak of fire. These occurrences may have even been due to poor connections at the devices. Aluminium conductors were soft and yielded to contact pressures resulting in high contact resistance and consequent development of hot spots. Inadequate sizing and improper installation of rising mains with Aluminium conductors in high rise building also contributed to the material getting a bad name.

Many switchgear components were made compact with terminals, suitable for receiving Copper conductors. When Aluminium conductors were terminated for the same ampacity, hot spots developed in some cases. The problem has now been overcome. Many components are now designed to receive Aluminium conductors or provide with adapter terminal plates to overcome this situation.

The markets, however, could not ignore the relative costs of Coper and Aluminium. Countries, where Copper was imported but had large deposits of Aluminium, actively encouraged the use of Aluminium by imposing trafiffs. Though the pure form of Aluminium did suffer from many shortcomings as a replacement for Copper, thanks to continued research in metallurgy and alloy