Power cable models for cable trays

Tray cables (TC) and TC-ER cables are the primary types of power cables designed for installation in cable trays, offering durability, safety, and compliance with NEC standards.

Types of Power Cables

Tray Cable (TC) is a multi-conductor cable designed for power, control, and lighting circuits in industrial and commercial environments. It features enhanced insulation and jacketing to withstand mechanical stress, moisture, oil, sunlight, and chemical exposure, making it suitable for harsh conditions.

T

C cables are rated for 600 volts and are UL listed for tray installation, ensuring compliance with NEC Article 336. Tray Cable with Exposed Run Rating (TC-ER) is similar to standard TC but is specifically rated for exposed runs outside the tray for distances up to six feet, provided the cable is properly supported and secured. TC-ER cables are also UL listed and designed for industrial power and control circuits.

Other cable types sometimes used in trays include Metal-Clad (MC) cables, which can also serve as 600-volt motor power cables, offering additional mechanical protection.

Installation Considerations

Cable Tray Types: Power cables can be installed in ladder, ventilated, solid-bottom, or wire-mesh trays depending on environmental conditions and heat dissipation requirements. Ampacity and Derating: Cables in trays have reduced ampacity compared to free-air installations due to restricted airflow and mutual heating effects from bundled cables. Metal trays can also induce eddy currents, further affecting conductor resistance.

Spacing and Support: Proper spacing, securing, and support are essential to prevent overheating and mechanical damage. Rung spacing of 6–9 inches is recommended for optimal cable management. Environmental Ratings: Tray cables are available for indoor, outdoor, corrosive, hazardous, or high electrical noise environments.

Many are exposure-rated (ER) and undergo crush and impact testing.

Standards and Compliance

All power cables installed in cable trays should be UL listed and marked as cable tray rated. Installation must comply with NEC Section 392 and related articles, which cover fill capacity, ampacity, splicing, and securing requirements. Following manufacturer specifications and local codes ensures safe and reliable operation.

Summary

For power distribution in cable trays, TC and TC-ER cables are the most commonly used, offering flexibility, durability, and compliance with NEC standards. Proper installation, spacing, and consideration of ampacity derating are critical to maintain safety and performance in industrial and commercial electrical systems.