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. The maximum pulling tension for stranded loose tube cable and ribbon cable is 600 lbF (2,700 Newtons). Refer to the cable specification sheet for the specific allowed. Recommendation ITU-T L. 100 describes characteristics, construction, test methods, and performance criteria of optical fibre cables installed by pulling method for duct and tunnel application. It. • Loose Loose Tube Tube containing containing fibres fibres and and filled filled with with a a suitable suitable water water tightness tightness compound.
