Correct marking of cable trays

Cable trays must be marked to indicate voltage hazards, grounding suitability, and compliance with safety standards, with labels placed at regular intervals and designed according to NEC and ANSI guidelines.High-Voltage Markings

Cable trays carrying conductors rated over 600 volts must be labeled “DANGER — HIGH VOLTAGE — KEEP AWAY”. These labels should be placed at intervals no greater than 10 feet along the tray and must comply with NEC Section 110.21(B), which requires effective warning through words, colors, and symbols. Labels cannot be handwritten except for variable information, and should follow ANSI Z535.4-2011 standards for product safety signs, including font, capitalization, and symbol usage to clearly communicate the hazard .

Grounding and Equipment Markings

If a cable tray is used as an Equipment Grounding Conductor (EGC), the manufacturer should provide a permanent label on the tray's side rail indicating the tray's cross-sectional metal area and UL classification for use as an EGC. This ensures that the tray meets NEC requirements for electrical continuity and fault current capacity. If the tray cannot serve as an EGC, a separate conductor must be installed, and the tray should be marked accordingly .

Compliance and Certification Labels

Cable trays may also carry UL, CE, or other certification marks to indicate compliance with national or international standards. These markings confirm that the tray meets mechanical, electrical, and safety requirements, and may include information about material, finish, and environmental suitability .

Placement and Visibility

• Labels should be clearly visible and durable under environmental conditions.
• Hazard warnings should be placed at entry points, junctions, and along the tray at regular intervals.
• Grounding and certification labels should be permanent and legible, typically on the side rails or other accessible surfaces.

Summary

Proper cable tray markings include:

• High-voltage warning labels for trays carrying >600V circuits.
• Grounding suitability labels if the tray is used as an EGC.
• Certification marks (UL, CE, etc.) for compliance verification.
• Placement at regular intervals and in visible locations to ensure safety and code compliance . These markings help ensure electrical safety, regulatory compliance, and proper identification of cable tray functions in industrial and commercial installations.