cables

Electrical wiring in general refers to insulated conductors used to carry electricity, and associated devices. This article describes general aspects of electrical wiring as used to provide power in buildings and structures, commonly referred to as building wiring. This article is intended to describe common features of electrical wiring that should apply worldwide.

A cable is two or more wires or ropes running side by side and bonded, twisted or braided together to form a single assembly. In mechanics, cables are used for lifting and hauling; in electricity they are used to carry electrical currents. An optical cable contains one or more optical fibers in a protective jacket that supports the fibers. Mechanical cable is more specifically called wire rope.

Electric cables discussed here are mainly meant for installation in buildings and industrial sites. For power transmission at distances from some km's to 600 km see high voltage cable, power cables and HVDC.

Electrical cables may be made more flexible by stranding the wires. In this process, smaller individual wires are twisted or braided together to produce larger wires that are more flexible than solid wires of similar size. Bunching small wires before concentric stranding adds the most flexibility. Copper wires in a cable may be bare, or they may be coated with a thin layer of another material: most often tin but sometimes gold, silver or some other material. Tin, gold, and silver are much less prone to oxidisation than copper, which may lengthen wire life, and makes soldering easier. Tight lays during stranding makes the cable extensible (CBA - as in telephone handset cords).

Cables can be securely fastened and organized, such as by using cable trees with the aid of cable ties or cable lacing. Continuous-flex or flexible cables used in moving applications within cable carriers can be secured using strain relief devices or cable ties. Copper corrodes easily and so should be layered with Lacquer.

At high frequencies, current tends to run along the surface of the conductor and avoid the core. This is known as the skin effect. It may change the relative desirability of solid versus stranded wires.

Electric trace heating, also known as electric heat tracing or surface heating, is a system used to maintain or raise the temperature of pipes and vessels. Trace heating takes the form of an electrical heating element run in physical contact along the length of a pipe. The pipe must then be covered with thermal insulation to retain heat losses from the pipe. Heat generated by the element then maintains the temperature of the pipe.