When solid bottom trough tray is installed outdoors, or indoors in humid locations, and EMI/RFI shielding protection is not required, it is recommended that 1⁄4”weep holes be drilled into the tray bottoms at the sides and in the middle every 3 feet to limit water. When solid bottom trough tray is installed outdoors, or indoors in humid locations, and EMI/RFI shielding protection is not required, it is recommended that 1⁄4”weep holes be drilled into the tray bottoms at the sides and in the middle every 3 feet to limit water. Ladder cable tray without covers provides for maximum air flow, dissipating heat produced in current carrying conductors. Dust buildup is minimal compared to other types of cable tray, such as ventilated trough or solid bottom. In areas where there is the potential for dust to accumulate, ladder. 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. A rung spacing of 6 to 9 inches (150 to 230 mm) is preferable when. Containment routes frequently run between electrical cupboards, risers, comms rooms, and service zones, meaning openings need to be drilled through blockwork, concrete, brick, or precast elements. Cable tray wiring systems do not require the degree of details to cope with the moisture problems as do the conduit wiring systems. At an industrial facility just. This section describes specific requirements, products, and methods of execution relating to cable management systems including tray, tray connectors, supports, brackets, engineered seismic bracing, vertical and/or horizontal offsets, grounding, and hardware for a complete system.