Can bare wires be placed in cable trays

Bare wires should generally not be placed directly in cable trays, especially aluminum trays, due to corrosion and grounding concerns; insulated conductors are recommended with bonding connections made where necessary.

Key Considerations

Material Compatibility: Bare copper conductors should not be installed in aluminum cable trays because moisture can cause electrolytic corrosion between the copper and aluminum, potentially compromising the tray and conductor integrity. If aluminum trays are used, it is safer to use insulated conductors and remove insulation only at bonding points with tin- or zinc-plated connectors for grounding purposes . Grounding and Bonding: Cable trays themselves can serve as an equipment grounding conductor (EGC) if they meet minimum cross-sectional area requirements and are properly bonded. However, for circuits with high ground-fault protection (above 600 A for steel trays or 2000 A for aluminum trays), the tray cannot serve as the EGC, and a separate grounding conductor must be installed . NEC Compliance: According to NEC Article 392, cable trays are intended to support various wiring methods, including power, control, and communication circuits. The NEC specifies that the smallest single conductor allowed in a tray is 1/0 AWG, and cables must be secured at intervals and supported to prevent stress . Bare conductors are not explicitly listed as permitted for general use in trays, except as part of grounding systems where bonding is required. Practical Installation: Most tray cables, such as Type TC (Tray Cable) or Type ITC (Instrumentation Tray Cable), consist of insulated conductors with optional bare or covered grounding conductors. These cables are designed for tray use and provide protection against physical damage, moisture, and electrical faults . Bare wires outside of grounding applications are not recommended due to safety and durability concerns.

Summary

• Do not place bare wires directly in aluminum trays; use insulated conductors instead.
• Bare conductors may be used for grounding if properly bonded and compatible with the tray material.
• Follow NEC Article 392 for conductor sizing, support, and securing requirements.
• Use tray-rated cables (TC, ITC, PLTC) for power, control, or instrumentation circuits to ensure safety and compliance . By adhering to these guidelines, installations remain safe, code-compliant, and resistant to corrosion or electrical hazards.