Your most pressing National Electrical Code (NEC) questions answered
Q. What labeling does the Code require in regard to arc flash hazard warning?
A. Electrical equipment, such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers, in other than dwelling units that are likely to require examination, adjustment, servicing, or maintenance while energized must be field-marked to warn qualified persons of the danger associated with an arc flash from short circuits or ground faults. The field-marking must be clearly visible to qualified persons before they examine, adjust, service, or perform maintenance on the equipment [110.16].See the definition of "Qualified Person" in Art. 100.
This rule is meant to warn qualified persons who work on energized electrical systems that an arc flash hazard exists so they'll select proper personal protective equipment (PPE) in accordance with industry-accepted safe work practice standards.
As noted in Informational Note 1 in 110.16: NFPA 70E, Standard for Electrical Safety in the Workplace, provides assistance in determining the severity of potential exposure, planning safe work practices, and selecting personal protective equipment.