Electricity kills. It causes electrical explosions, vaporizes metal, and maims workers across the United States each year. One of the most deadly electrical hazards is arc flash.
Arc flash is a powerful burst of heat and light, resulting from electric current that is passed through the air when insulation or isolation between electrified conductors is not sufficient to withstand the applied voltage. The flash is often over in the blink of an eye, but the results can cause severe injury.
On average, five to 10 arc flash incidents occur on the job every day in the U.S., according to the Institute of Electrical and Electronics Engineers (IEEE) and National Fire Protection Association (NFPA) Arc Flash Collaborative Research Project. Approximately 2,000 workers are admitted to burn centers annually for extended injury treatment caused by arc flash.
While electricity can be unpredictable, one of the easiest ways to protect workers is by providing equipment with arc flash labels and arc flash warning signs.
Arc Flash Label Requirements
Arc flash labels are required by law. OSHA’s detailed rules for electrical safety require employers to mark electrical equipment with “voltage, current, wattage, or other ratings as necessary” (29 CFR 1910.303(e)).
The agency also mandates the use of signs or similar devices to “warn and protect employees from hazards which could cause injury due to electric shock, burns, or failure of electric equipment parts” (29 CFR 1910.335(b)).
Though arc flash warning labels are not specifically mentioned, they are clearly within the spirit of these rules. Because of this, most worksites use the NFPA 70E Standard for Electrical Safety in the Workplace. While it's not legally required in all areas, it's widely respected and followed, and is used as a reference for safe practices worldwide.
NFPA 70E 2015 Changes
Arc flash standards adapt to changes in technology and research. Every three years, NFPA releases a new edition of NFPA 70E. The newest edition was released in 2015, and major changes to the standard include simplified label requirements, and a more effective arc flash personal protective equipment (PPE) category system.
Originally, only very basic arc flash warnings were required; however each standard update has adjusted the requirements for label details, such as arc flash boundaries and nominal system voltage. Graphic Products has summarized the 2015 standard in a complimentary Arc Flash Labeling Guide.
What's Required on an Arc Flash Label?
Labels can save lives. Arc flash labels are described in NFPA 70E section 130.5(C), which states that workplace electrical equipment that is likely to be examined, adjusted, or serviced while energized should be labeled with all three of the following:
Nominal System Voltage: A quick and convenient designator to identify the voltage class of a given piece of equipment or circuit and the potential shock hazard or degree of danger present.
Arc Flash Boundary: The distance from the equipment at which an unprotected person would probably receive a second-degree burn in the event of an arc flash.
Protective Equipment: The PPE needed to work on the labeled equipment safely. There are four choices for this requirement; however incident energy/working distance information and arc flash PPE categories cannot be used on the same equipment:
Available Incident Energy at a Working Distance: A label displays the amount of thermal energy to be expected at a given working distance from an arc fault. Arc flash energies must be calculated, using highly technical data.
Arc Flash PPE Category: These categories, numbered one to four, group together equipment of roughly similar hazards and assign a set of required PPE to the entire category. Higher numbers equal higher danger.
Minimum Arc Rating of Clothing: An arc rating (AR) number is assigned to PPE by clothing manufacturers, which represents the amount of thermal energy (in cal/cm2) that the clothing can block or absorb.
Site-Specific Level of PPE: NFPA 70E also allows facility-specific systems to describe PPE requirements.
There are several ways to create labels for electrical equipment. Some electrical analysis software can create label designs that are ready to print; you can also design custom labels. DuraSuite Labeling Software, included with most DuraLabel industrial label and sign printers, feature an up-to-date module for arc flash labeling that complies with NFPA 70E. These arc flash printers create standard-compliant and professional-looking labels.
ANSI Z535 Layout
Uniform labels and consistent design help workers recognize safety hazards. In addition to the requirements outlined in NFPA 70E, arc flash labels should follow the label format described in the American National Standards Institute’s ANSI Z535 standard.
This is a widely-accepted system that promotes ease of recognition and understanding, and elements of the standard have been incorporated by reference into OSHA regulations. The ANSI Z535 format for signs and labels uses a boldly-colored header along the top of the sign, with a signal word to indicate the degree of risk. A second field, usually white with black printing, is used for the main text and other details.
Components of an ANSI Z535 Hazard Sign:
Header or Signal Word Panel: A rectangular panel at the top of the sign, filled with a color to match the type of sign.
Safety Alert Symbol: The symbol showing an exclamation point in a triangle, included on the header for any sign that warns about possible injuries.
Signal Word: The word in the header that draws attention and identified the type of the sign (such as "Danger" or "Warning").
Message Panel: The white panel beneath the header that includes the detailed information of the sign.
Safety Message: Text in the message panel that describes the hazard.
The different types of signs (identified by their signal words and header colors) indicate different kinds of hazards. The two kinds most often used for arc flash labels are "Danger" and "Warning." Warning signs (with an orange header) indicate a hazard that could result in serious injury or death, if the sign is ignored. Danger signs (with a red header) are for the most extreme hazards, which are likely to result in serious injury or death. Exactly where to draw the line between the two is up to each facility, but the decision should be reasonable and consistent.
Where Should Arc Flash Labels Be Placed?
Arc flash hazard labels need to be carefully placed, and then maintained and updated. The National Electrical Code (NEC) requires that hazard labels be located so that they are clearly visible to personnel before beginning maintenance or inspection. Workers must be able to see and read the label before they are exposed to an arc flash hazard, which means labels must be large enough to be legible from a safe position. The placement and size of a sign will depend on the severity of the hazard and the nature of the installation.
All workers must be able to see and read the label, including those who might not be involved in working on the equipment, but are just passing through the area.
Other Arc Flash Label Content
Labels may include additional safety precautions. Changes such as re-organizing the material for a customized presentation, or adding a company logo or contact information, may be beneficial.
Arc flash labels commonly include other elements such as:
Shock Boundaries: Most electrical equipment that poses an arc flash hazard also presents a shock hazard. These labels often include the Limited Approach Boundary and the Restricted Approach Boundary.
Date of Assessment: NFPA 70E requires the arc flash risk assessment for each piece of equipment to be reviewed at least once every five years, or whenever the circuit is altered. Labels must be updated whenever the relevant information has changed.