Those cables run through public cable trays

Cables can run through public cable trays, but only electrical, power, signal, and communication cables are permitted, and installations must comply with NEC standards and safety practices.Permitted Cable Types and RegulationsCable trays are designed to support and route electrical, power, signal, and communication cables, including optical fiber, in both commercial and industrial settings . According to the National Electrical Code (NEC) Section 300-8, cable trays cannot carry water, air, gas, drainage, steam, or any non-electrical service . NEC Section 318-3 specifies the types of cables allowed, including medium voltage (MV) and single conductor cables, with certain restrictions for industrial installations .Installation PracticesCables in trays must be securely fastened to maintain spacing, prevent sagging, and segregate different types of cables when necessary . Vertical and horizontal installations are both acceptable, but vertical trays may allow cables to hang if not tied down, while horizontal runs may require tie-downs to meet spacing and ampacity requirements . Adequate clearance around trays is essential for installation and maintenance, typically 12 to 18 inches between stacked trays and the ceiling .Tray Types and Fill RulesCable trays come in several configurations:Ladder Tray: Open design with side rails and rungs, ideal for power cables and heavy loads, providing excellent ventilation .Ventilated Trough Tray: Solid bottom with ventilation slots, suitable for medium-voltage cables or areas needing debris protection .Solid-Bottom Tray: Fully enclosed, offering maximum protection from debris or liquids but with more restrictive fill rules due to heat dissipation concerns . Fill limits vary by cable type and tray design, and exceeding these limits can cause overheating or maintenance difficulties .Safety ConsiderationsWalking on cable trays is not permitted due to fall hazards, risk of equipment damage, and potential contact with live conductors . Proper tie-downs, spacing, and separation of power and signal cables are critical to maintain safety and performance .SummaryRunning cables through public cable trays is standard practice for electrical and communication systems, provided that:Only approved cable types are used.NEC regulations and fill limits are followed.Cables are properly secured and spaced.Adequate access and clearance are maintained.Safety measures prevent physical damage and hazards. Following these guidelines ensures a safe, compliant, and maintainable cable tray installation in public or shared spaces .