Chapter 30. Properties and ratings of current carrying
Physical and electrical properties of aluminium and copper conductors
Ampacity tables of copper and aluminium conductors
Properties for aluminium and copper conductors
In Table 30.1 we provide the general properties of aluminium and copper conductors. The table also makes a general comparison between the two widely used metals for the purpose of carrying current.
Important definitions of properties of a metal
For ease of application of the above table we give below important definitions of the mechanical and electrical properties of a metal.
Physical and mechanical properties
1. Specific heat (This is a physical property) The specific heat of a substance is the heat required to raise the temperature of its unit mass by 1°C.
This is the force per unit area expressed in kgf/mm2 and is represented in a number of ways, depending upon the type of force applied, e.g.
• Tensile stress: the force that will stretch or lengthen the material and act at right angles to the area subjected to such a force.
• Ultimate tensile strength: the maximum stress value as obtained on a stress–strain curve (Figure 30.1).
• Compressive stress: the force that will compress or shorten the material and act at right angles to the area subjected to such a force.
• Shearing stress: the force that will shear the material and act in the plane of the area and at right angles to the tensile or compressive stress.