There are many myths, beliefs, and opinions in the industry on why aluminum conductors should or should not be used in certain applications. The use of aluminum conductors causes questions and concerns for many electricians, engineers, inspectors, and owners.
Aluminum has the features of low cost and low weight. Current electrical grade aluminum (Al) conductors are actually an aluminum alloy. Aluminum conductors can be round or bar shaped. Both of these shapes are used in a large majority of transmission and distribution circuits as well as industrial plants. The primary reasons for using aluminum conductors are its lower cost and low weight to conductivity ratio.
Modern aluminum alloys have been improved. Round conductor prior to the mid 1970s was made of aluminum alloy 1350, which was essentially It had undesirable mechanical characteristics such as a large coefficient of thermal expansion and a susceptibility to bending and creep failure. Many fires were reported with alloy 1350. The current alloy utilized for round conductor inside buildings is the 8000 series, which became commercially available in the mid 1970s. To improve its mechanical characteristics over pure aluminum, additional elements were added to the 8000 series. In addition, it undergoes an annealing process.
Aluminum is a proven, cost effective means to conduct electricity. The issues of the early aluminum alloy 1350 have been addressed in the 8000 series alloys, the proven connection methods and the connectors in use today. Aluminum and aluminum alloys should be considered as acceptable materials for All Aluminum Conductors in power circuits provided the correct series of material is used and appropriate design, installation, and connection techniques are utilized.
Aluminum Conductors are most commonly used for making cables. Cable, in electrical and electronic systems, a conductor or group of conductors for transmitting electric power or telecommunication signals from one place to another. Electric communication cables transmit voice messages, computer data, and visual images via electrical signals to telephones, wired radios, computers, teleprinters, facsimile machines, and televisions. There is no clear distinction between an electric wire and an electric cable. Usually the former refers to a single, solid metallic conductor, with or without insulation, while the latter refers to a stranded conductor or to an assembly of insulated conductors. With fibre-optic cables, made of flexible fibres of glass and plastic, electrical signals are converted to light pulses for the transmission of audio, video, and computer data.
The most common type of electric power cable is that which is suspended overhead between poles or steel towers. These aerial cables consist of a number of wires, usually of copper or aluminum, twisted (stranded) together in concentric layers. Copper or aluminum is chosen for high electrical conductivity, while stranding gives the cable flexibility. Because aerial cables are frequently subjected to severe environmental stresses, alloys of copper or aluminum are sometimes used to increase the mechanical strength of the cable, although at some detriment to its electrical conductivity. A more common design is to include in the stranded cable assembly a number of high-strength, noncorrosive steel wires. Many aerial cables, especially those operating at high voltages, are bare (uninsulated). Cables operating at lower voltages frequently have coverings of asphalt-saturated cotton braid, polyethylene, or other dielectric (nonconducting) material. These coverings offer some protection against short-circuiting and accidental electric shock.