Several rules apply. OSHA 1910.335(b) requires safety signs at electrical hazards, and the National Electrical Code requires warning signs at the entrances to electrical rooms (NEC 110.27) and on equipment over 600 volts (NEC 110.34), plus an arc-flash label under NEC 110.16. Our high voltage signs use the OSHA and ANSI danger format so they satisfy those marking requirements.
Because high voltage is an immediate, life-threatening hazard, the sign uses the Danger red, black, and white color scheme with a white DANGER header, per OSHA 1910.145. People sometimes associate these signs with yellow or orange because the lightning-bolt hazard symbol sits in a warning triangle and utility signage has used yellow. The severity is what sets the header color, and for high voltage that is red.
Post a sign at every entrance and access point, and directly on the enclosure or panel that holds the hazard. Mount it at eye level, well-lit and unobstructed, so a worker sees it before reaching the equipment. For an electrical room or closet, a Do Not Enter high voltage sign on the door is standard.
Enough that a sign is always in view from the outside. For a fenced substation, post signs on every side of the fence and at each gate, spaced along the perimeter, plus on the equipment inside.
Yes. For substations, transformers, and transmission infrastructure, choose engineer-grade or high-intensity reflective aluminum. It resists weather and stays readable at night or under a flashlight, which is critical for outdoor energized equipment. Rust-proof aluminum holds up for years outdoors where plastic or vinyl would not.
Yes. For an electric fence, post high voltage warning signs at intervals along the fence so the charge is clearly marked. For overhead lines, use overhead power line signs and an "unlawful to operate equipment within 10 feet of high voltage lines" sign near cranes and lifts. Both keep people and equipment at a safe distance.
Round out the area with arc flash labels, electrical panel signs, and lockout/tagout tags where equipment is serviced. A custom danger sign lets you add an exact voltage, clearance distance, or instruction. For a facility-wide or substation order, call our team at (800) 952-1457 (Mon – Fri, 8:00am to 7:00pm EST) or email customerservice@smartsign.com for a quote.
We make high voltage signs that warn workers and the public away from equipment that can cause a fatal shock or arc flash. Because high voltage is a life-threatening hazard, these are almost always Danger-level signs, marked with the lightning-bolt symbol so the risk is instantly clear in any language. They secure electrical panels, transformers, substations, utility rooms, and overhead lines. Choose from stock voltage-rated and keep-out messages plus custom, reflective, and bilingual options on durable aluminum, plastic, and vinyl.
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