A ventilated tray has openings in the bottom of the tray, allowing some air circulation around the cables, water drainage, and allowing some dust to fall through the tray. Small cables may exit the tray through the ventilation openings, which may be either. 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. This type of cable tray is useful because the ladder rungs allow easy access to the cables from the top or bottom. Cable trays are crucial for organizing cables, keeping them safe from physical damage, and ensuring their proper functioning over time. Understanding the. According to the National Electrical Code standard of the United States, a cable tray is a unit or assembly of units or sections and associated fittings forming a rigid structural system used to securely fasten or support cables and raceways. Several types of tray are used in different. T&B channel tray systems are fabricated from a corrosion-resistant metal (low-carbon steel, stainless steel or an aluminum alloy) or from a metal with a corrosion-resistant finish (zinc or epoxy).