Most Fiber cables don't Need to be Replaced. If installed and protected correctly against technical and environmental conditions, they can last: 25–50 years (outdoor plant infrastructure, long-haul wiring) 15–30 years (indoor building wiring systems) 10–20 years (FTTH plant drop. Most Fiber cables don't Need to be Replaced. Thus, understanding the full lifecycle of fiber optic cables is essential not only for technical success but also for maximizing ROI and minimizing future upgrade costs. Suppose replacing all the test cables and couplers restores your gold-standard product to the previous good measured values. However, the actual replacement frequency depends on several.