Fiber cable should not be stepped on, driven over, pinched under equipment or overly compressed with tight cable ties. Fiber optic cables consist of thin glass or plastic fibers that transmit data as light signals. The cables can be single-mode or multi-mode, with single-mode cables used for long-distance transmissions and. When pulling fiber optic cables through conduit, navigating corners is the most dangerous part of the journey. They are installed in the same general location by the same people for the same general purpose. They even look similar, both before and after installation.