Power cables for cable trays in communication equipment rooms

Use UL-listed, tray-rated power cables such as Type TC or MC, installed in properly supported and segregated cable trays to ensure safety, EMC compliance, and reliable operation in communication equipment rooms.

Types of Power Cables

For cable trays in communication equipment rooms, the most commonly used power cables include:

• Type TC (Tray Cable): Factory-assembled cables with two or more insulated conductors under a non-metallic jacket, rated for 600 volts. Suitable for industrial power or control circuits, flame-retardant, and UL-listed for use in cable trays, raceways, and certain outdoor locations. TC cables can also be used in Class 1, Division 2 hazardous locations and may include TC-ER (Exposed Run) cables for short unsupported runs to equipment .
• Metal-Clad (MC) Cables: Provide additional mechanical protection with a metallic sheath, suitable for 600-volt power circuits and often used where physical protection is required . All cables should be UL-listed and marked as cable tray rated, ensuring compliance with flammability, mechanical, and temperature standards.

Cable Tray Selection and Installation

• Tray Types: Cable trays can be ladder, ventilated, solid-bottom, or wire mesh, depending on the environment and heat dissipation requirements . Ladder trays are common for power cables due to good ventilation, while solid-bottom trays may be used for sensitive instrumentation or communication cables to reduce EMI .
• Material Considerations: Steel, stainless steel, or aluminum trays are used depending on corrosion resistance, mechanical load, and environmental conditions . Aluminum offers excellent corrosion resistance and a high strength-to-weight ratio, while stainless steel is preferred in highly corrosive environments .
• Support and Spacing: Trays must be securely supported using wall brackets, suspended supports, or ceiling mounts. Rung spacing of 6–9 inches is recommended for proper cable support and to maintain minimum bend radius .

Segregation and EMC Considerations

• Segregation: Power and communication cables should be separated to minimize electromagnetic interference (EMI). Use separate trays or dividers within trays for high-voltage and low-voltage cables .
• EMC Compliance: Follow good engineering practices for grounding and bonding of trays and cables. Proper earthing reduces EMI and ensures safe operation of sensitive communication equipment .

Installation Best Practices

• Avoid overfilling trays; adhere to fill capacity and ampacity limits as per NEC Article 392 .
• Maintain proper bend radius when routing cables to prevent insulation damage.
• Secure cables at intervals to prevent sagging and mechanical stress.
• Use covers or barriers where necessary to protect cables from dust, moisture, or accidental contact .

Summary

For communication equipment rooms, UL-listed Type TC or MC power cables installed in properly supported, ventilated, and segregated cable trays provide safe, reliable, and code-compliant solutions. Attention to EMC, mechanical protection, and tray fill ensures long-term performance and minimizes interference with sensitive communication systems .