A ladder cable tray without covers permits the maximum free flow of air across the cables. This allows the heat produced in the cable's conductors to effectively dissipate. Ladder trays allow: Scientific studies and NEC guidance recognize that open tray systems permit higher ampacity than enclosed systems. In Class II, Division 2 Hazardous (Classified) Locations (Dust), the types of cables that are allowed to be installed in cable trays must be in ladder or ventilated trough cable trays. Solid bottom cable trays are not allowed to be installed in Class II, Division 2 locations [1993 NEC Section 02-. The Cable Tray Institute (CTI) was founded in 1991 to support the cable tray industry by engaging in research, development, education, and the dissemination of information designed to promote, enhance, and increase the visibility of the industry. However, they offer limited ventilation, so they may not be ideal for high-heat applications unless heat-resistant cables are used. protection of solid bottom trays.
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