Chapter 5

Hazardous (Classified) Locations — Specific Scope. Articles 511 through 517 cover occupancies or parts of occupancies that are or may be hazardous because of atmospheric concentrations of flammable liquids, gases, orvapors, or because of deposits or accumulations of materials that may be readily ignitible. General. The general rules of this Code and the provi‐ sions of Articles 500 through… read more »

Zone 20, 21, and 22 Locations for Combustible Dusts or Ignitible Fibers/ Flyings Informational Note: Text that is followed by a reference in brackets has been extracted from NFPA 499-2013, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installation in Chemical Process Areas. Only editorial changes were made to the extracted text to make… read more »

Zone 0, 1, and 2 Locations Informational Note: Text that is followed by a reference in brackets has been extracted from NFPA 497-2012, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas. Only editorial changes were made to the extracted text to make it consistent with… read more »

Intrinsically Safe Systems Scope. This article covers the installation of intrinsically safe (I.S.) apparatus, wiring, and systems for Articles 500 through 516.Informational Note: For further information, see ANSI/ISA-RP 12.06.01-2003, Recommended Practice for Wiring Methods for Hazard‐ ous (Classified) Locations Instrumentation — Part 1: Intrinsic Safety. Definitions.•Different Intrinsically Safe Circuits. Intrinsically safe circuits inwhich the possible interconnections have not been evaluated and identified… read more »

Class III Locations Part I. General 503.1 Scope. Article 503 covers the requirements for electri‐ cal and electronic equipment and wiring for all voltages in Class III, Division 1 and 2 locations where fire or explosion hazards may exist due to ignitible fibers/flyings. General. Equipment installed in Class III locations shall be able to function at full… read more »

Class II Locations Part I. General 502.1 Scope. Article 502 covers the requirements for electri‐ cal and electronic equipment and wiring for all voltages in Class II, Division 1 and 2 locations where fire or explosion hazards may exist due to combustible dust. Explosionproof Equipment. Explosionproof equipment and wiring shall not be required and shall not be… read more »

Class I LocationsPart I. General501.1 Scope. Article 501 covers the requirements for electri‐ cal and electronic equipment and wiring for all voltages in Class I, Division 1 and 2 locations where fire or explosion hazards may exist due to flammable gases or vapors or flamma‐ ble liquids.Informational Note: For the requirements for electrical and electronic equipment… read more »

Hazardous (Classified) Locations, Classes I, II, and III, Divisions 1 and 2 Informational Note: Text that is followed by a reference in brackets has been extracted from NFPA 497-2012, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, and NFPA 499-2013, Recommended Practice for the Classification of Combustible Dusts… read more »