How can fiber optic cables go bad?
Fiber optic cables can go bad for many of the same reasons that copper cables can go bad. Depending on the environment they are installed in, they may be susceptible to being cut or damaged by impacts and bending, which results in a partial or complete failure to transmit light.
Connectors can also be the source of faults, either due to contaminants or the connector housing wearing out and failing. These faults commonly present themselves as excessive light signal loss as well.