NFPA 70E is only applicable if its an adopted standard, if you are under OSHA, it is used. In Washington we are under WISHA and they have different standards.
But, the NEC, since the 2002 edition has had a requirement for arc flash warning, the requirements have changed over the years, but basically its
110.16 Arc-Flash Hazard Warning.
(A) General. Electrical equipment, such as switchboards, switchgear, panelboards, industrial control panels, meter socket enclosures, and motor control centers, that is in other than dwelling units, and is likely to require examination, adjustment, servicing, or maintenance while energized, shall be field or factory marked to warn qualified persons of potential electric arc flash hazards. The marking shall meet the requirements in 110.21(B) and shall be located so as to be clearly visible to
qualified persons before examination, adjustment, servicing, or maintenance of the equipment.
So NPFA70E may be applicable, but the NEC defiantly requires labeling. Typically the AHJ will enforce this on new installs