Outdoor fiber optic cable contraction

5-foot sag for a 150-foot span helps cables handle thermal expansion and contraction. Service loops are essential for maintenance. During installation, all curvatures should be smooth. Segregate fiber optic cable from heavy copper cables to avoid. These are the outdoor fiber optic cables you see strung along telephone poles (aerial), installed inside an underground duct, or even buried directly below ground. At its core, the optical fibers are enclosed within protective layers that are resistant to pressure, water, and ultraviolet radiation.