Flash Protection Labels and Signs

National Electric Code 110.16 Flash Protection: Switchboards, panel
boards, industrial control panels and motor control centers, in other than
dwelling occupancies, that 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.