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. This publication is intended as a practical guide for the proper and safe* installation of cable ladder systems, cable tray systems, channel support systems and associated supports. The mechanical and electrical characteristics, tests, certifications, overall quality management, recommendations mentioned. 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. With all the choices in cable trays styles, ladder, ventilated, solid bottom and wire basket, it can be difficult to know which is the right one for your application. These rungs are spaced at regular intervals and provide a structure that resembles a ladder—hence the name. Alternative names include: cable runway and.