Ignoring thickness is one of the most common causes of tray deflection and field failures. Ladder cable tray is available in widths of 6, 9, 12, 18, 24, 30, 36, 42 and 48 inches with rung spacings of 6, 9, 12 or 18 inches. Note that wider rung spacings and wider cable tray widths decrease the overall strength 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. How to ensure project success by understanding cable tray thickness requirements and standard recommendations. torque is sufficient for all thread rod nuts.