For cables larger than 4/0 AWG, cables are installed in a single layer (no stacking) and the sum of cable diameters must not exceed the tray width. This article is about Storage, Handling and Preservation of Cable Tray and Accessories for commercial buildings, plants and refinery projects as per international codes and standards. Electrical materials shall be new and unused. A rung spacing of 6 to 9 inches (150 to 230 mm) is preferable when. When dealing with any mixture of cables, it is crucial to follow the National Electrical Code (NEC) regulations, specifically 392. For cables 4/0 AWG and smaller, the maximum fill is based on cross-sectional area, and cables may be stacked. Boxes and bags should be stacked onto. Recognize electrical cable tray misuse that can lead to electric shock and arc-flash/blast events and fires caused by overheating. 305(a)(3), or comparable standards promulgated by States.