Optical fiber experiences various stresses during its lifetime starting from proof-testing, cabling, installation and in-service life. For long term reliability prediction, it is required to determine in-service lifetime and in-service failure rate for various fiber stress histories like constant tension in buried cable or sudden jerk during cable installation, and adverse cable handling like accidental cable “dig-ups”. However, a fiber length that is subjected to a constant applied service stress which doesn’t vary with time, is the most common situation for which reliability prediction is made. Thus, there is a need to understand impact on lifetime of fibers exposed to abnormal stress-time profiles such as in cable “dig-ups”. In this paper various fiber lifetime prediction models are discussed. Fiber lifetime and safe stress are predicted based on stress-time histories and long length (20 m) tensile strength distributions.
