PVC works well in duct banks and open trenches. Fiberglass is reserved for applications requiring exceptional compressive strength or chemical resistance. Corrugated HDPE reduces pulling friction for runs inside existing. Whether you are building a duct bank for a municipal broadband project, pulling cable through an existing conduit system, or speccing an inside-plant pathway, these principles apply. Material selection matters for the environment. HDPE is the right choice for most underground and outside-plant. Underground cables are pulled in conduit that is buried underground, usually 1-1. In extreme cold climates, cables may need to be buried at greater depths where there temperatures are colder and frost penetrates to. Installing fiber optic cables underground involves far more than digging trenches and placing cables. Typical wall thickness follows ASTM F771 (Schedule 40 equivalent) or the heavier ASTM F894 for telecommunications use. Proper conduit installation requires attention to pulling tension limits, bend radius requirements, lubricant selection, and innerduct. Another benefit of using the fiber optic cable in protective conduit is that it protects the breakable glass fibers from physical pressures in the ground. Directly buried cables are exposed to challenges such as rocks, roots, rodents, excavation, frost heaves, and many others.
