Cable trays typically carry power, control, and communication cables that are rated for tray use and comply with NEC standards.

Power and Control Cables

The most common cables in cable trays are Type TC (Tray Cable), which consist of two or more insulated conductors under a non-metallic jacket. These cables are rated for 600 volts and are suitable for industrial power circuits, control circuits, and hazardous locations when properly identified. TC cables can be flame-retardant and are often used in both indoor and outdoor applications, including direct burial if specified. Type MC (Metal-Clad) cables are also used for power distribution above 600 volts or where additional mechanical protection is required .

Communication and Signaling Cables

Cable trays also accommodate communication, control, and signaling circuits, including optical fiber cables and low-voltage data lines. Cables rated for different voltages can share the same tray if they comply with NEC requirements, but those above 600 volts must be separated by a solid barrier from lower-voltage cables . These cables are often shielded to reduce electromagnetic interference, especially in industrial environments.

Installation Considerations

Cables in trays must be UL listed and marked as cable tray rated, and installation must follow NEC Article 392 guidelines. This includes proper support, securing, and spacing to prevent overfilling and maintain ampacity. Exposure-rated (TC-ER) cables can leave the tray for short distances (up to six feet) if supported and secured . Single conductor cables from 1/0 AWG to 4/0 AWG have specific maximum rung spacing requirements to ensure safe support .

Summary

In essence, cable trays carry a variety of power, control, and communication cables, all of which must be rated for tray use, UL listed, and installed according to NEC standards. The choice of cable depends on voltage, environmental conditions, and mechanical protection requirements, ensuring safe and organized cable management in industrial and commercial installations .