Cable trays are placed inside the cable trays

No, cable trays should not be placed inside other cable trays; each tray must be independently accessible and maintain proper spacing for safety and code compliance.

Key Considerations

Accessibility and Maintenance: The National Electrical Code (NEC) requires that cable trays be exposed and accessible to allow installation, maintenance, and removal of cables. Adequate space must be maintained around trays to accommodate cable pulling equipment and ensure safe access . Placing one tray inside another would obstruct access and violate these requirements. Spacing Requirements: When multiple trays are installed near each other, proper vertical or horizontal spacing is essential. For example, vertical spacing between floor-mounted trays should be at least 150 mm, and horizontal spacing between parallel trays should generally be no less than 0.6 meters to allow maintenance, airflow, and prevent interference . Nesting trays would eliminate this clearance. Cable Fill and Heat Dissipation: Each tray has a maximum fill rate, typically not exceeding 50% of its cross-sectional area, to allow airflow and prevent overheating . Placing a tray inside another would reduce airflow, increase heat buildup, and could exceed fill limits, creating a fire hazard. Structural and Safety Concerns: Cable trays are designed to support cables directly. Installing a tray inside another could compromise structural integrity, create uneven load distribution, and interfere with grounding or bonding requirements . Each tray must be securely supported and independently bonded if used as an equipment grounding conductor. Best Practice: If additional cable capacity is needed, install separate trays in parallel or stacked with proper spacing, rather than nesting one tray inside another. This ensures compliance with NEC, maintains accessibility, and allows proper ventilation and cable management . In summary, cable trays must be installed independently with adequate spacing and accessibility. Placing one tray inside another is not recommended and would violate safety and code standards.