Warning signs for high-voltage cable trays

Cable trays carrying conductors over 600 volts must be marked with “DANGER — HIGH VOLTAGE — KEEP AWAY” signs at intervals not exceeding 10 feet, following NEC and ANSI standards.Regulatory Requirements

According to NEC 392.18(H), any cable tray containing conductors operating over 600 volts must have permanent, legible warning signs stating: “DANGER — HIGH VOLTAGE — KEEP AWAY” . These signs must be placed in readily visible locations along the cable tray, with a maximum spacing of 10 feet (3 meters). Labels must comply with NEC 110.21(B), which requires effective hazard communication using proper words, colors, and symbols. Handwritten labels are not permitted except for variable information. ANSI Z535.4-2011 provides guidance on font, color, capitalization, and symbol usage for safety labels .

Placement and Visibility

• Signs should be installed at eye level or in locations where they are clearly visible to personnel.
• In industrial settings where only qualified personnel have access, signs may be placed where necessary to ensure safe maintenance and operation .
• Both indoor and outdoor cable trays require durable signage resistant to abrasion, chemicals, and UV exposure for long-term visibility .

Materials and Design

High-voltage safety signs are typically made from aluminum, high-impact plastic, or adhesive vinyl . Key features include:

• High-contrast colors (yellow or red backgrounds with black text)
• Reflective or photoluminescent options for low-light areas
• Bilingual text if required for workforce communication
• Durable adhesives for permanent installation on cable trays .

Commercial Options

Several manufacturers provide NEC-compliant signs specifically for high-voltage cable trays:

• Panduit PPS0410D79-NEC: 4”x10” label, abrasion, chemical, and UV resistant, suitable for indoor/outdoor use .
• Emedco High Voltage Signs: Available in multiple sizes, reflective or photoluminescent, bilingual options, and designed for industrial environments .
• SafetySign.com Electrical Warning Signs: OSHA and ANSI compliant, heavy-duty materials, suitable for panels, transformers, and cable trays .

Best Practices

• Ensure all cable trays over 600 volts are marked consistently.
• Use standardized wording and symbols to avoid confusion.
• Inspect signs regularly for damage or fading and replace as needed.
• Combine signage with training and restricted access to enhance safety. By following these guidelines, facilities can maintain compliance with NEC and OSHA standards while protecting personnel from high-voltage hazards.