The NEC explicitly states that conductive optical fiber cables are not allowed to occupy the same cable tray or raceway as the aforementioned electrical conductors. The key difference here is safety. This includes conductors for electric light, power, Class 1, non-power-limited fire alarms, Type ITC, or medium-power network-powered broadband communications circuits. Installation methods for both wire and optical fiber communications cables are similar. This includes corners and exit slots of trays.
