Cable tray systems are often used for cable management in commercial projects to support insulated electric cables on flat roofs. 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 Types: Only use conductors rated for open-air environments, such as Tray Rated (Type TC) or Metal-Clad (Type MC) cables. Clearances: Maintain at least 12 inches of vertical clearance above trays for installation and maintenance access (2026 NEC update). For demanding requirements, rely on PohlCon's many years of expertise. 1) Use Cable Trays! The first and most obvious of these best practices is that you should always use cable trays.