operating conditions of the equipment, is not capable, due to arcing or thermal effects, of igniting the flammable gas-air, vapor-air, or dust-air mixture. Normal operation includes opening, shorting, or grounding the field wiring.

Nonincendive Field Wiring Apparatus. Apparatus intended to be connected to nonincendive field wiring.

FPN: For further information see ANSI/ISA-12.12.01-
2000, Nonincendive Electrical Equipment for Use in

Class I and II, Division 2, and Class III, Divisions I and 2

Hazardous (Classified) Locations.

Oil Immersion. Electrical equipment immersed in a protective liquid in such a way that an explosive atmosphere that may be above the liquid or outside the enclosure cannot be ignited.

FPN: For further information, see ANSI/UL 698-1995, Industrial Control Equipment for Use in Hazardous (Classified) Locations.

Purged and Pressurized. The process of (1) purging, supplying an enclosure with a protective gas at a sufficient flow and positive pressure to reduce the concentration of any flammable gas or vapor initially present to an acceptable I level; and (2) pressurization, supplying an enclosure with a protective gas with or without continuous flow at sufficient pressure to prevent the entrance of a flammable gas or vapor, a combustible dust, or an ignitible fiber.

FPN: For further information, see ANSI/ NFPA 496-
2003, Purged and Pressurized Enclosures for

Electrical Equipment.

Unclassified Locations. Locations determined to be neither Class I, Division 1; Class I, Division 2; Class I, Zone 0; Class I, Zone 1; Class I, Zone 2; Class II, Division

1; Class II, Division 2; Class III, Division 1; Class III, Division 2; Zone 20; Zone 21; Zone 22; or any combination thereof.

500.3 Other Articles. Except as modified in Articles

500 through 504, all other applicable rules contained
in this Code shall apply to electrical equipment and
wiring installed in hazardous (classified) locations.

500.4 General.

(A) Documentation. All areas designated as hazardous (classified) locations shall be properly documented. This documentation shall be available to those authorized to design, install, inspect, maintain, or operate electrical equipment at the location.

(B) Reference Standards. Important information relating to topics covered in Chapter 5 may be found in other publications.

FPN No. 1: It is important that the authority having jurisdiction be familiar with recorded industrial experience as well as with the standards of the National Fire Protection Association (NFPA), the American Petroleum Institute (API), and the Instrumentation, Systems, and Automation Society (ISA) that may be of use in the classification of various locations, the determination of adequate ventilation, and the protection against static electricity and lightning hazards.
FPN No. 2: For further information on the classification of locations, see NFPA 30-2008, Flammable and

Combustible Liquids Code; NFPA 32-2007, Standard for Drycleaning Plants; NFPA 33-2007, Standard for Spray Application Using Flammable or Combustible Materials; NFPA 34-2007, Standard for Dipping and Coating Processes Using Flammable or Combustible Liquids; NFPA 35-2005, Standard for the Manufacture of Organic Coatings; NFPA 36-2004, Standard for Solvent Extraction Plants; NFPA 45-2004, Standard on Fire Protection for Laboratories Using Chemicals; NFPA 55-2005, Standard for the Storage, Use, and Handling of Compressed Gases and Cryogenic Fluids in Portable and Stationary Containers, Cylinders,