Optical cable is usually placed in a 25 to 40 mm inside diameter (ID) sub-duct which is placed into an existing larger diameter communications conduit. Most communications conduits can be fitted with three or four sub-ducts. Sub-ducts are often referred to as innerducts. Fiber optic "cable" refers to the complete assembly of fibers, other internal parts like buffer tubes, ripcords, stiffeners, strength members all included inside an outer protective covering called the jacket. They are defined by the international standard IEC 60794-5-20 and must meet specific requirements for impact resistance, pressure, and bending. Applications include telecom, SCADA command and control. “This specification covers cable in conduit (CIC), which is a smooth-walled, coilable, high-density polyethylene (HDPE) conduit (duct) that contains preassembled wires and cables.
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