Standard Fiber Optic Cables: These cables are not designed for direct burial and require protection from a conduit or duct system when installed underground. Tray cables are multi-conductor cables manufactured and tested to withstand industrial environments. They're commonly used in power distribution, control. The purpose of this AE Note is to outline the use of fiber optic cables in “tray rated” environments. Cable trays are a support system for electrical cables, power, signal, and communication and optical fiber cables. NEC section 300-8 does not permit any tube, pipe, or equal for water, air gas, drainage, steam, or any service other than electrical in raceways or cable trays containing. Conduit provides excellent mechanical protection and segregation, ideal for exposed public routes or high‑risk zones.