What type of cable is used in indoor cable trays

Type TC (Tray Cable) and its variants, such as TC-ER, are the most commonly used and code-compliant cables for indoor cable trays.

Overview of Tray Cables

Tray cables (TC) are multi-conductor cables specifically designed for installation in cable trays, raceways, or supported by messenger wires. They are built to withstand mechanical stress, moisture, heat, and chemical exposure, making them ideal for indoor industrial and commercial environments.

T

C cables are UL listed and meet National Electrical Code (NEC) requirements for tray installations (NEC Article 336) and are typically rated for 600 volts, with some versions rated higher for specialized applications.

Common Types for Indoor Use

Type T

C – General Purpose Tray CableSuitable for power, lighting, and control circuits. Can be installed in cable trays, raceways, or direct burial if rated. Flame-retardant and durable for indoor industrial environments.

Type TC-ER – Tray Cable with Exposed Run RatingDesigned for short exposed runs (up to 6 feet) between the tray and equipment without conduit. Includes crush- and impact-resistant jacketing for added protection.

Type IT

C – Instrumentation Tray CableUsed for low-voltage control, signal, and communication circuits (≤150V, ≤5A). Available in shielded or unshielded versions to reduce electrical noise.

PLT

C – Power Limited Tray CableIntended for Class 2 and Class 3 circuits, such as alarm, intercom, and building automation systems. Rated for 300V and suitable for indoor tray installations.

Key Considerations

Voltage Rating: Ensure the cable voltage rating matches the application (commonly 300V for power-limited circuits, 600V for general power/control circuits). Mechanical Protection: Indoor tray cables should be crush- and impact-resistant, especially if trays are in high-traffic areas. Flame Retardancy: Most indoor tray cables are flame-retardant to comply with safety codes.

U

L Listing: Always select UL-listed tray-rated cables to meet NEC compliance. Cable Fill and Support: Follow NEC Article 392 for tray fill capacity, securing intervals, and support requirements.

Summary

For indoor cable trays, Type TC and TC-ER cables are the most versatile and widely used options for power and control circuits. For low-voltage instrumentation or signal applications, ITC or PLTC cables are appropriate. Always ensure cables are UL-listed, flame-retardant, and installed according to NEC guidelines to maintain safety and performance.