Do I Need to Use Condit for All Fiber Optic Cable Installations? The necessity of using cable depends on the installation environment. While indoor installations may not require conduit in some cases, outdoor, underground, underwater, or aerial installations almost always do. Installing fiber optic cables underground involves far more than digging trenches and placing cables. Whether you're working on a data center buildout, a city-wide fiber network, or upgrading rural network links, selecting the right cable conduit ensures overall. A conduit is a protective tube or channel that houses the fiber optic cables, shielding them from moisture, dust, physical stress, and other environmental factors.