22 (A) (1) (a) through 392. 22 (A) (1) (c) outlines the rules for placing multiple conductor cables within a cable tray. Cable tray is the preferred wiring method for industrial facilities, data centers, and large commercial buildings where routing dozens or hundreds of cables through individual conduits would be impractical and expensive. NEC Article 392 governs cable tray installations, covering tray types, fill. 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. A rung spacing of 6 to 9 inches (150 to 230 mm) is preferable when the cable tray cont d for instrumentation and control applications that require. Cable tray barriers can be used to separate conductors operating over 600 volts from other conductors in the same tray operating at 600 volts or less. ANY MIXTURE. Many cable tray rated cables include a crush and impact test as part of the listing and are rated as exposure rated (ER). In case of high power use, to meet the demand of currentAnd in order for the current to be carried at the demanded high powers to be met, the method of parallel.