Cables

A cable is two or more wires running side by side and bonded, twisted, or braided together to form a single assembly. The term originally referred to a nautical line of specific length where multiple ropes, each laid clockwise, are then laid together anti-clockwise and shackled to produce a strong thick line, resistant to water absorption, that was used to anchor large ships.

In mechanics, cables, otherwise known as wire ropes, are used for lifting, hauling, and towing or conveying force through tension.

In electrical engineering cables are used to carry electric currents. An optical cable contains one or more optical fibers in a protective jacket that supports the fibers.

Ropes made of multiple of strands of natural fibers such as, hemp, sisal, manila, and also cotton have been used for 1000 years for hoisting and hauling. By the 19th century, deeper mines as well as construction of larger and larger sailing ships increased demand for stronger ropes. In 1830 the Royal Navy defined a cable as three hawser laid (clockwise) ropes, each approximately 120 fathoms in length, laid anti-clockwise, tightly twisted and shackled to a resulting length of approximately 100 fathoms. The tight twists, shortened the overall length of the ropes but both strengthened the ropes and reduced the ability of the rope to absorb water making them ideal for mooring.

Improvements to steelmaking techniques made high-quality steel available at lower cost, and so wire ropes became common in mining and other industrial applications while continuing the practice of anti-cyclical twists to strengthen them even further. By the middle of the 19th century, manufacture of large submarine telegraph cables was done using machines similar to those used for manufacture of mechanical cables. As the move from rope to wire happened, the specific length associated with a cable fell into disuse.

As electricity became even more ubiquitous the practice of using more than bare copper led to groupings of wires and various sheathing and shackling methods that resembled the mechanical cabling so the term was adopted for electrical wiring. In the 19th century and early 20th century, electrical cable was often insulated using cloth, rubber or paper. Plastic materials are generally used today, except for high-reliability power cables. The term has also come to be associated with communications because of its use in electrical communications.

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Wikipedia