Cables in cable trays are typically supported, routed, and protected using tray-rated cables such as TC, TC-ER, and ITC, installed according to NEC standards for safety and performance.

Purpose of Cable Trays

Cable trays are designed to support, route, and protect electrical and communication cables in industrial, commercial, and utility environments. They provide a structured pathway that simplifies installation, maintenance, and future expansion while reducing the risk of physical damage to cables .

Types of Cables Commonly Used

1. TC – Tray Cable: Multi-conductor cables suitable for power, control, and lighting circuits. Rated for 600 volts, TC cables can be installed in cable trays, raceways, and outdoor locations if supported by a messenger wire. They are UL listed and may be used in hazardous locations when properly identified .
2. TC-ER – Tray Cable with Exposed Run Rating: Designed for exposed runs outside of trays for distances up to six feet, TC-ER cables meet crush and impact requirements and are continuously supported and secured .
3. ITC – Instrumentation Tray Cable: Used for instrumentation and control applications, available in shielded or unshielded constructions, sometimes with metal armor for additional protection . All cables used in trays should be UL listed and marked as cable tray rated, ensuring compliance with flammability, mechanical, and temperature standards .

Installation Considerations

• Support and Spacing: Cables should be supported at intervals recommended by the manufacturer, typically every 6 to 9 inches for small instrumentation cables, to prevent sagging and maintain proper bend radius .
• Fill Capacity: NEC Article 392 specifies maximum fill percentages to avoid overheating and maintain electrical performance .
• Securing Cables: Cables must be secured at intervals not exceeding six feet, especially for TC-ER cables transitioning from trays to equipment .
• Environmental Protection: Cable trays can be ventilated or solid, and materials such as aluminum, stainless steel, or fiberglass are chosen based on corrosion resistance and mechanical strength .

Best Practices

• Avoid running high-temperature piping directly over cable trays to prevent heat damage; if unavoidable, use insulation or shielding .
• Maintain clear access for maintenance and replacement of cables.
• Follow NEC guidelines for splicing, grounding, and separation of power and control cables to minimize interference and ensure safety . By selecting the appropriate tray-rated cables and following proper installation practices, cable trays provide a safe, organized, and durable solution for managing electrical and control wiring in complex installations.