Fiber is best used in applications where you expect the run (from point A to point B) to exceed 200-250 feet. Why? Because CAT5E & CAT6 are limited to only 200-250 feet before data loss would begin to occur. Whereas, with fiber the run can exceed 5 miles allowing it to be used in many more applications. Fiber also is not susceptible to ElectroMagnetic Interference (EMI), which means it can be ran within close proximity of power lines without affecting connectivity.