Overhead spans of open conductors and open multiconductor cables shall have a vertical clearance of not less than 2. The Fiber Optic Association, Inc. (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. 300 do these apply to optical fiber cables and raceways [770. 22, which applies when. This comprehensive guide delves into the installation requirements, explores the two primary cable types—self-supporting and messenger-supported—and offers practical insights to ensure optimal performance in diverse environments. Understanding Overhead Fiber Optic Cable Overhead fiber optic. For these rare occurrences, the NEC ® provides minimum safe distances that the overhead feeder must be kept above a roof surface in the event that the feeder happens to cross over a building.