Laying cable trays in the stairwell

Cable trays can be safely installed in stairwells, including vertical runs, provided proper support, clearance, and cable management practices are followed.Vertical Installation and ComplianceIt is common practice to install cable trays in vertical positions, such as stairwells, risers, or shafts. Vertical cable trays maintain their structural integrity over long periods, often exceeding 25–30 years, as long as cables are securely fastened and tie wraps are periodically inspected . The percent fill for vertical trays is the same as for horizontal trays, so cable loading calculations do not change based on orientation . NEC guidelines require that only electrical cables be installed in these trays, prohibiting water, gas, or other services in the same pathway .Types of Cable Trays Suitable for StairwellsLadder-type trays: Open design with side rails and rungs, allowing excellent ventilation and easy access for cable installation and maintenance. Ideal for heavy-duty power cables and long spans .Perforated trays: Provide ventilation for light to medium cable loads and help prevent moisture buildup .Solid-bottom trays: Offer complete protection for sensitive cables, reducing electromagnetic interference . The choice of tray depends on cable type, weight, and environmental conditions in the stairwell.Support and Installation ConsiderationsRoute planning: Mark horizontal and vertical runs according to approved shop drawings, ensuring no clashes with other services .Support spacing: Use appropriate hangers, brackets, or cleats to support the tray along the stairwell wall or structure. Supports must meet load requirements for current and future cable additions .Clearance: Maintain sufficient space for cable pulling, inspection, and future maintenance .Material handling: Store trays horizontally on flat surfaces with timber supports to prevent damage before installation .Maintenance and SafetyEnsure cables are fastened securely to prevent sagging or movement.Inspect tie wraps and fasteners periodically, especially for single-conductor cables, to maintain long-term integrity .Open designs like ladder trays allow easy inspection and heat dissipation, reducing the risk of overheating . By following these guidelines, cable trays in stairwells can provide a safe, organized, and durable solution for routing electrical, instrumentation, and communication cables.