How to install cable trays inside cable trays

Installing one cable tray inside another is generally not recommended due to safety, load, and code compliance concerns.

Code and Safety Considerations

Cable trays are designed as open structural systems to support electrical conductors, not to house other trays inside them.

According to NE

C Article 392, trays must remain accessible, maintain proper fill limits, and allow for adequate ventilation to prevent overheating of cables. Nesting trays could violate fill limits, reduce airflow, and create difficulty in maintenance or inspection. Additionally, cable trays are not intended to support the weight of another tray plus its cables unless specifically engineered for that purpose.

Load and Structural Concerns

Each tray has a maximum load capacity and recommended support spacing. Installing a tray inside another could exceed the load rating of the lower tray or its hangers, leading to mechanical failure. Proper support for nested trays would require independent hangers or structural reinforcement, which is rarely standard practice.

Practical Alternatives

Instead of nesting trays, consider these approaches: Side-by-side installation: Use multiple trays mounted on the same support structure with adequate spacing. This maintains accessibility and proper ventilation. Multi-tiered tray systems: Some installations use vertical stacking with separate hangers for each tray, ensuring each tray is independently supported and meets fill and clearance requirements.

Larger trays: Use a single tray with sufficient width and depth to accommodate all cables while staying within fill limits.

Conclusion

While physically possible in some cases, installing a cable tray inside another is not standard practice and may violate NEC requirements for accessibility, fill, and heat dissipation. The recommended approach is to use independent trays with proper support or a larger tray to safely manage cable routing.