Armored cables running in cable trays

Armored cables should be installed in cable trays with proper spacing, bend radius, and support to ensure safety, compliance, and long-term performance.

Selecting the Right Cable Tray

Choose a tray type based on cable load, ventilation, and environmental conditions. Ladder trays are ideal for heavy power cables because they allow air circulation and reduce heat buildup, while solid-bottom trays provide protection from debris or liquids but limit ventilation. Ventilated trough trays offer a balance for medium-voltage or smaller cables.

Preparing for Installation

Verify cable type and rating: Ensure the armored cable (SWA, STA, or AWA) meets the voltage, temperature, and environmental requirements. Check tray condition: Inspect for sharp edges, debris, or damage that could harm the cable insulation. Plan layout: Avoid overcrowding; cable fill should not exceed 40% of tray capacity to prevent overheating.

Laying the Cables

Maintain minimum bend radius: Typically 12–15 times the cable diameter to prevent insulation or armor damage. Use cable rollers or guides around corners. Organize cables: Lay cables in parallel runs, grouping by type or voltage, and avoid crossing over other cables unnecessarily.

Secure cables: Fix cables at regular intervals using approved clamps or ties to prevent sagging and movement.

Grounding and Termination

Properly earth the armor: Use the correct gland type (BW, CW, or A2) and ensure tight mechanical fixing to prevent arcing or overheating. Avoid mechanical stress: Do not overtighten clamps or bend cables sharply at terminations.

Compliance and Safety

Follow NE

C Article 392 for cable tray installation, including tray selection, fill limits, and separation of power and signal cables. Ensure adequate ventilation to prevent heat buildup, especially in solid-bottom trays. Use protective conduits or covers in areas with mechanical risk or exposure to moisture.

Additional Tips

Label cables for easy identification and maintenance. Avoid overfilling trays to maintain airflow and allow future cable additions. Use corrosion-resistant or halogen-free insulation in harsh environments to extend cable life.

By following these practices, armored cables in cable trays will maintain mechanical integrity, thermal performance, and electrical safety, ensuring reliable operation over time.