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 aluminum
is sometimes used because it 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 improves the solderibility of the bunch-, but it could be silver,
gold and another materials and of course the wire can be unplated - with no coating material)
on the individual wires provides lubrication for longest life.
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.
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