Wire and cable

Wire and cable are distinct but related ideas in engineering. Think of wire as a single metal strand, or perhaps thin metal strands twisted or interwoven together to act as a single mechanical strand. That strand may be covered, as with insulation to prevent electricity from traveling outside the path of the wire, or, when the wire is used as a structural reinforcement, covered with a coating to prevent corrosion.

Cable comes into existence when multiple wires are systematically bound together for a specific purpose. Among the simplest is two- or three-conductor cable for carrying electrical power, with the wires being relatively thick to carry power without overheating. Alternatively, a very common cable for carrying electronic signals uses thin wire, twisted into pairs; the geometry of the twist is very precise to preserve desired electronic characteristics.

Cable is commonly used not only for assemblies of multiple metallic strands, but for assemblies of fiber optic material, alone or in combination with metal. A "hybrid" fiber and metal cable might have only a steel wire to add mechanical support, copper wires to carry power to light the optical devices, or both.

Design tradeoffs

Regardless of the application, which could be electrical, structural, medical, etc., the minimal tradeoffs are using metal that is sufficiently strong to handle the load, but no larger or stronger in order to minimize weight and cost. Again independently of application, the environment of use must be considered; corrosion, for example, might be prevented either by choice of metal or of covering. A medical suture, for example, is of specific stainless steel, tantalum, or other corrosion-resistant metal. Alternatively, electrical conductors, which usually are copper, need covering not only for insulation but for protection from oxidation and other corrosion.