High density riser and plenum breakout cables for indoor and outdoor cable applications

The breakout cable is made up of an arrangement of optical fiber ribbon structures (10). Arranged above and/or below the optical fibers (12) in each of the ribbon structures are strength members (14,16). The combined optical fibers and strength members are surrounded by a sheath (18) thereby forming the high strength, sheathed optical fiber ribbon structure arrangement. A plurality of these individually sheathed ribbon structures (22,24,26,28) can be stacked to form higher density ribbon bundles (20), or subunits, which can be further surrounded by sheaths (30). Similarly, a large numbers of such high density ribbon bundle subunits can be combined within a protective sheath (42,68) to form cables (40,50) which can be pulled through risers and plenums in the construction of premises, such as apartment buildings or commercial buildings, or used in appropriate indoor/outdoor applications. Accordingly, even as subunits are broken out of the cables, and as ribbon structures are broken out of the subunits, the optical fibers will still be surrounded by high strength members which will help protect them from breakage.