What needs to be labeled?
It is important to understand that proper labeling of safety hazards often means following generalized safety standards and customizing them to your particular arc flash hazard.
Article 116.10 in the NEC states that relevant electrical equipment shall be “field marked to warn qualified persons of potential electric arc flash hazards.” This section requires switchboards, panelboards, industrial control panels, and motor control centers to be field marked to warn personnel of the potential electric arc flash hazards. While not every type of equipment is expressly named, industrial control panels covers every enclosure that may contain exposed energized conductors or components.
OSHA 29 CFR, 1910 clearly outlines regulations for hazard communication. Labeling of hazards is regulated in many hazardous environments, including environments where electrical, chemical or other hazards may impact safety. OSHA provides generalized standards for safety labeling, but does not necessarily state specific requirements for arc flash labeling.
>OSHA labeling standards
What needs to appear on the label?
Article 116.10 in the NEC states what equipment must be labeled, however the NEC leaves the content of the label up to the employer.
Article 130.3(C) in NFPA 70E dictates that the label show the available incident energy or required level of personal protective equipment. A hazard/risk category rating is typically used to indicate the required level of personal protective equipment. (For more information on arc flash hazard/risk categories, see section 130.7(C)(10) in the NFPA 70E standard.)
Article 130.7(E)(1) in NFPA 70E standard notes that the design and formatting of the labels should conform with ANSI Z535 Series of Standards For Safety Signs & Tags. Thus it is recommended that the header, message and pictogram, if used, be formatted according to ANSI standards. Currently there is not a widely-accepted symbol for indicating an arc flash hazard.
Neither the NFPA 70E nor the NEC requirements specify whether to use a “Danger” or “Warning” header; however, NFPA 70E does recommend identifying those situations in which there is an extreme hazard to the worker. A commonly used guideline is to use a red “Danger” header when the voltage is over 600 volts or when the incident energy is over 40 cals/cm2. If it is less than that threshold, an orange “Warning” header is used. It is imperative that consistency be maintained on all the labels throughout the facility.
It is also important that arc flash labels be able to withstand their usage environment. This means that the print should not fade, and the adhesive should be aggressive enough to avoid peeling. When necessary, a protective laminate should be applied to protect the printed surface from harsh chemicals and exposure to sunlight.
Sample Arc Flash Label