Aluminum cables and conductors are widely used in domestic, industrial and bare overhead power lines. The electric wire or cable forms the conducting link between one electrical equipment and another; it also constitutes the internal veins and arteries of electrical equipment. It may be lightly insulated as in a bell wire which connects the bell-push with the bell and the battery, or it may be heavily insulated as in the case of an underground high voltage power cable which links the electrical generating station of a city with the suburban substation or supply center. In size it ranges from a wire much thinner than the human hair used for winding the coils of hearing aids, to a heavily armored telegraph or telephone cable running along the bed or the ocean may be bare or insulated. A bare conductor is used as overhead line for telegraphy, telephony, and power transmission. When so used it is supported by, or suspended from porcelain, glass, or other insulators attached to wood, concrete or steel poles.
An insulated wire or cable consists of the conductor which provide the path for the electrical current when the circuit is completed; the insulation or dielectric which prevents direct contact between two or more conductors or between the conductor and any other object not intended to form a part of the electrical circuit; and the preservative material for protecting the dielectric and the conductor from abrasive, corrosive or other destructive action.
Formerly conductors were generally made of copper, primarily because copper has a high electrical conductivity approaching that of silver, which is the best known commercial conductor of electricity. Copper has high ductility and malleability which enables it to be drown into wires as fine as on thousandth of an inch in diameter. It can also be joined with ease by such processes as soldering, brazing and welding and is resistant to many forms of corrosion. Because of higher cost and low availability of copper, aluminum is replacing copper in most application in this field.