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. This blog will show how to install it. It forms a critical backbone for modern communication networks across both urban and rural environments. The methods described are intended for guideline use only, as it is impossible to cover all the various conditions that may arise during an installation. Fiber optic cable should not be coiled in a continuous direct on except for lengths of 100 ft (30 m) or less. The preferred size of the igure-eight coils is about 15 ft (4. Match trench method with the correct underground fiber structure (GYTS, GYTA53, GYTY53, micro-duct).