A cable is one or more wires or optical fibers bound together, typically in a common protective jacket or sheath. The individual wires or fibers inside the jacket may be covered or insulated. Combination cables may contain both electrical wires and optical fibers. Electrical wire is usually copper because of its excellent conductivity, but aluminium is sometimes used because it is lighter or costs less.
Electrical cables may be made 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. A thin coat of a specific material (usually tin
-which improved striping of rubber, or for low friction of moving conductors, but it could be silver
and another materials and of course the wire can be bare - with no coating material) on the individual wires. Tight lays during stranding makes the cable extensible (CBA - as in telephone handset cords).
Bundling the conductors and eliminating multi-layers ensures a uniform bend radius across each conductor. Pulling and compressing forces balance one another around the high-tensile center cord that provides the necessary inner stability. As a result the cable core remains stable even under maximum bending stress.
Cables can be securely fastened and organized, such as 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.
In the 19th century and early 20th century, cable was often insulated using cloth, rubber and even paper. Plastic materials are generally used today, except for high reliability power cables. There are four types of plastic insulation used in telecommunications cables today: solid, cellular, foam skin and skin-foam-skin.
Cables as a fire hazard
, sometimes the cable jacketing is seen as a potential source of fuel for a fire. To limit the spread of fire along cable jacketing, one may use cable coating materials or one may use cables with jacketing that is inherently fire retardant. Teck cable or metal clad cables, may have exterior organic jacketing, which is often stripped off by electricians in order to reduce the fuel source for accidental fires. In Europe
in particular, it is often customary to place inorganic wraps and boxes around cables in order to safeguard the adjacent areas from the potential fire threat associated with unprotected cable jacketing.
In applications powering sensitive electronics, keeping unwanted EMI/RFI
from entering circuits is important. This can be accomplished passively with shielding along the length of the cable or by running the cable in an enclosure separate from any other wires which may induct noise. It can also be actively achieved by use of a choke
designed to restrict the cables' ability to conduct certain frequencies.
Types of cable
Cables can be sorted into several categories and types. Generally it can by sorted into two main groups, structural and informatic.
Basic cable types are as follows:
Based on construction and cable properties it can be sorted into the following:
The leading global producers of wire and cable include (in no particular order): Clynder Cables, Canare, Draka, General Cable, Belden, Nexans
, India, igus
, Sumitomo Electric Industries
, Furukawa Electric, Hitachi Cable
, Southwire, Marmon Group
, LS Cable
, Fujikura, Tyco
, Lapp, Wonderful Hi-Tech, Walsin Lihwa and Wilms Group, and Jainson Cables - India.