Installing the bottom light of the cable tray

Bottom-mounted lights on a cable tray should be securely attached using proper supports, maintaining clearance, and following NEC guidelines for safety and accessibility.

Planning and Preparation

Before installation, plan the tray route and lighting layout. Ensure the tray type (ladder, solid-bottom, or ventilated trough) can support the additional weight of the lights and that the tray is properly mounted with supports spaced according to load requirements, typically 1.5 to 3 meters apart depending on tray type and load . Establish elevation benchmarks using a laser level or transit to maintain consistent height along the tray run .

Mounting the Lights

• Attachment Method: Use brackets, clamps, or hangers designed for the tray type. Avoid using the tray itself as a lifting or attachment point for heavy loads .
• Clearance: Maintain at least 12 inches of vertical clearance above the tray for cable access and maintenance, as recommended by NEC 392 .
• Weight Considerations: Ensure the combined weight of cables and lights does not exceed the tray's maximum load capacity (typically 318–340 kg per hanger), .
• Alignment: Position lights evenly along the tray to provide uniform illumination and prevent stress on the tray structure .

Electrical and Safety Considerations

• Wiring: Use conductors rated for open-air environments, such as Tray Rated (Type TC) or Metal-Clad (Type MC) cables .
• Separation: Keep power and control cables separated to prevent electromagnetic interference (EMI) if lights are powered from the same tray system .
• Grounding: If using metallic trays, ensure proper bonding and grounding of both the tray and the lighting fixtures .
• Cable Management: Secure wiring with cable ties or straps, leaving slack for expansion or future adjustments .

Final Checks

• Verify that all lights are securely mounted and aligned.
• Confirm that tray fill limits are not exceeded and that ampacity derating is considered for high-density cable runs .
• Test the lighting circuit for proper operation and ensure compliance with NEC 392 and local electrical codes . By following these steps, bottom-mounted lights can be safely and effectively installed on a cable tray system, providing illumination without compromising cable support or safety.