How to connect wires in a cable tray

Wires should not be spliced or connected inside a cable tray; all connections must occur in approved junction boxes or enclosures.

Key Considerations

Cable trays are designed as support systems, not as enclosed raceways. They provide mechanical support and organization for electrical, signal, and communication cables, but they do not protect splices or connections from mechanical damage, moisture, or fire hazards.

According to NE

C Article 392, cable trays are intended to carry Type TC (Tray Rated) or metal-armored (Type MC) cables, which are durable enough for open-air exposure, but the code does not permit making electrical connections directly within the tray. Splicing inside a tray is unsafe because: The tray is exposed to physical impacts, which could damage unprotected splices. Open-air trays do not provide the insulation and containment required for electrical connections.

It violates NEC requirements, which mandate that all splices and terminations occur in listed junction boxes or enclosures.

Proper Practice

Route cables continuously through the tray without splicing. Make all connections in junction boxes mounted outside the tray or at equipment terminations. Secure cables to the tray using ties or clamps to prevent sagging and maintain proper spacing.

Maintain grounding and bonding of the tray system if it is used as an Equipment Grounding Conductor (EGC), ensuring all sections are electrically continuous.

Summary

While cable trays provide excellent support and organization for electrical wiring, they are not intended for making wire connections or splices. All splices must be made in approved enclosures to comply with NEC standards and ensure safety, reliability, and maintainability of the electrical system.