A practical, engineering-focused guide to planning and installing underground fiber optic cables with the right cable structure, trench design and protection level for long-life, low-risk networks. Match trench method with the correct underground fiber structure (GYTS, GYTA53 . Underground cables are pulled in conduit that is buried underground, usually 1-1. 2 meters (3-4 feet) deep to reduce the likelihood of accidentally being dug up. In extreme cold climates, cables may need to be buried at greater depths where there temperatures are colder and frost penetrates to. Using Conduits to Protect Underground Fiber Cables In areas exposed to moisture, mechanical stress, or future excavation, installing fiber optic cable within an underground conduit provides an additional layer of protection. Fiber optic cable is sensitive to xcessive pulling, bending. Installing fiber underground is one of the most durable ways to protect a network's backbone — when it's done right. Direct-burial fiber cable eliminates the need for continuous conduit runs and can be faster and more cost-effective on long, open runs. (FOA) was founded in 1995 to help develop the workforce to build the fiber optic networks to support a rapid expansion in communications and the Internet.