Single conductor cables and Type MV cables are not allowed to be installed in solid bottom cable trays [1993 NEC Section 318-3 (b)]Single conductor cables and Type MV cables are not allowed to be installed in solid bottom cable trays [1993 NEC Section 318-3 (b)]The types of cables, allowed in cable trays, and the wiring methods permitted in cable trays can be found in NEC Section 392. This Section also lists various corresponding NEC Articles which describes the conditions of use, and installation requirements for a particular class or type of. Answer: No. 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. en completely installed, without damage either to conductors or structural system use maintain spacing or to keep cables in place when the tray is ect the minimum bend ra-dius for cables as they exit the bottom of the cable tray. Cable weight, heat generation, bend radius, environmental exposure, and maintenance access all directly influence which cable tray type is technically appropriate and code-compliant. Tray cable is comprised of two or more insulated conductors, a ground conductor, and a protective jacket. SHIELDED TRAY CABLE Selecting shielded or.