How large a conduit should be used for outdoor four-core optical fiber cable

Quick Answer: For most telecom OSP fiber builds, design to a 40% fill ratio — cable cross-sectional area should occupy no more than 40% of the conduit's inner bore area. Undersized conduit is one of the most common and expensive mistakes in outside plant fiber builds. A conduit that's too small either stops the pull mid-run — forcing a costly splice point — or creates enough friction to damage the cable jacket before it ever reaches the destination. A conduit. 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. Next, select the type of conduit you are specifying. [pdf]