A letter to OSHA’s Directorate of Enforcement Programs (DEP) regarding the agency's requirements and the National Fire Protection Association's (NFPA) 70E-2004, Standard for Electrical Safety in the Workplace, posed the following question: When work must be performed on energized electric equipment that is capable of exposing employees to arc-flash hazards, does OSHA require the marking of the electric equipment to warn qualified persons of potential electric arc-flash hazards — i.e., as required by NFPA 70E-2004?1

The short answer

The short answer (from OSHA’s Edwin G. Foulke, Jr.): No.

“OSHA has no specific requirement for such marking,” Foulke wrote in reply to a 2006 letter from Joanne B. Linhard of ORC Worldwide in Washington, D.C. “A requirement to mark equipment with flash hazard warnings was not included in the 1981 Subpart S revision.

However...

“However, paragraph (e) of §1910.303 requires employers to mark electrical equipment with descriptive markings, including the equipment's voltage, current, wattage, or other ratings as necessary. OSHA believes that this information, along with the training requirements for qualified persons, will provide employees the necessary information to protect themselves from arc-flash hazards. 

Additionally, in §1910.335(b), OSHA requires employers to use alerting techniques (safety signs and tags, barricades, and attendants) . . . to warn and protect employees from hazards which could cause injury due to electric shock, burns or failure of electric equipment parts. Although these Subpart S electrical provisions do not specifically require that electric equipment be marked to warn qualified persons of arc-flash hazards, §1910.335(b)(1) requires the use of safety signs, safety symbols, or accident prevention tags to warn employees about electrical hazards (e.g., electric-arc-flash hazards) which may endanger them as required by §1910.145.” 

1 Section 400.11 of NFPA 70E-2004 states: Switchboards, panelboards, industrial control panels, and motor control centers that are in other than dwelling occupancies and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.