You have been asked to design a backbone cable connecting two large campus buildings. Your pathways will include using conduits, maintenance holes, and one section of 100 m (328 ft) of direct buried o

Distribution cables are designed for indoor use with lightweight jackets that are not rated for UV exposure, soil contact, or the moisture levels present in an outdoor direct buried environment.

A loose tube cable without water blocking compound lacks adequate moisture protection for the direct buried segment, where gel or water-swellable material is required to prevent water migration along the cable core.

Loose tube cable is the standard outside plant (OSP) cable design for direct buried and underground applications because its buffer tubes allow fibers to float freely, accommodating thermal expansion and mechanical stress without fiber strain. The water blocking compound - either gel-filled tubes or dry water-swellable tape - is essential for direct buried segments where soil moisture and hydrostatic pressure continuously threaten moisture ingress into the cable core. Together, these features make this cable type the appropriate choice when the pathway includes maintenance holes, conduit, and open-trench direct burial in the same run.

Armored distribution cable adds crush and rodent resistance but the distribution cable base construction remains an indoor-rated design not suited to the thermal cycling and moisture conditions of a direct buried OSP application.

A distribution cable with water blocking compound still relies on an indoor cable architecture that is not engineered to withstand the outdoor environmental stresses of direct burial, including UV degradation and soil pressure.