Span of fire-fighting cable trays in Ethiopia

Long-span cable trays in industrial and commercial applications can typically span up to 12.2 meters (40 feet) between supports, depending on tray type, load, and fire protection requirements.Standard Cable Tray SpansIn Ethiopia, high-quality ladder-type and perforated cable trays are available from local manufacturers such as NAHMA Precision Metal Products in Addis Ababa, suitable for electrical and industrial applications . Standard ladder-type cable trays generally require supports at intervals of 1.2 to 3 meters (4–10 feet) depending on the tray width, rung spacing, and load. Fire-rated cable trays, designed to maintain circuit integrity during a fire, may require closer support spacing to comply with UL, BS EN, or DIN standards .Long-Span Cable Tray SolutionsFor installations where fewer supports are feasible, such as roadway crossings, pipe bridges, or long straight runs, long-span aluminum cable trays are recommended. Products like the T&B AH1-8 series allow supports every 12.2 meters (40 feet) for straight sections, reducing installation costs and labor . These trays are constructed from extruded aluminum with H-beam side rails and ladder-style rungs, providing high strength-to-weight ratios and corrosion resistance. Deflection at mid-span is calculated based on load and tray width, and continuous spans may reduce deflection by up to 50% .Fire Protection ConsiderationsFire-fighting cable trays must maintain circuit integrity during a fire. Fire protection can be achieved using intumescent coatings, firestop pillows, or fire-resistant caulks around penetrations . The spacing of supports may also be influenced by fireproofing requirements, as additional bracing can help prevent tray collapse under high temperatures. Fire-rated trays are tested to standards such as UL, BS EN, or DIN 4102-12, ensuring cables remain functional during fire emergencies .Practical RecommendationsFor standard ladder trays, use support spacing of 1.2–3 meters depending on load and width.For long-span aluminum trays, supports can be spaced up to 12.2 meters (40 feet) for straight runs.Ensure fire-rated installations comply with UL or DIN standards and include appropriate firestop measures.Consider tray width, rung spacing, and load rating when determining support intervals to minimize deflection and maintain safety.By combining local availability with long-span solutions and fire protection measures, Ethiopian projects can achieve both cost efficiency and compliance with fire safety standards.