Containment or Ventilation. [34:Figure 6.4(a)]
above the floor and extending 6 m (20 ft) horizontally in all directions from the Class I, Division 1 or Class I, Zone 1 location.
Exception: This space shall not be required to be considered a hazardous (classified) location where the vapor source area is 0.46 m 2 (5 ft 2) or less and where the contents of the open tank trough or container do not exceed 19 L (5 gal). In addition, the vapor concentration during operation and shutdown periods shall not exceed 25 percent of the lower flammable limit outside the Class I location specified in
516.3(B)(4). [34:6.4.4 Exceptionl
(7) Open Containers. All space in all directions within
600 mm (2 ft) of the Division 1 or Zone 1 area
surrounding open containers, supply containers, spray
gun cleaners, and solvent distillation units containing
flammable liquids, as well as the area extending 1.5 m
(5 ft) beyond the Division 1 or Zone 1 area up to a
height of 460 mm (18 in.) above the floor or grade
level. [33:6.6.2]
(D) Enclosed Coating and Dipping Operations. The space adjacent to an enclosed dipping or coating
process or apparatus shall be considered unclassified.
[34:6.5.3]
Exception: The space within 900 mm (3 ft) in all directions from any opening in the enclosures shall be classified as Class I, Division 2 or Class I, Zone 2, as applicable. [34:6.5.2]
(E) Adjacent Locations. Adjacent locations that are cut off from the defined Class I or Class II locations by tight partitions without communicating openings, and within which flammable vapors or combustible powders are not likely to be released, shall be unclassified.
(F) Unclassified Locations. Locations using drying, cur ing, or fusion apparatus and provided with positive me chanical ventilation adequate to prevent accumulation of flammable concentrations of vapors, and provided with effective interlocks to de-energize all electrical equipment (other than equipment identified for Class I locations) in case the ventilating equipment is inoperative, shall be permitted to be unclassified where the authority having jurisdiction so judges.
FPN: For further information regarding safeguards, see NFPA 86-2007, Standard for Ovens and Furnaces.
516.4 Wiring and Equipment in Class I Locations.
(A) Wiring and Equipment — Vapors. All electrical wir- ing and equipment within the Class I location (containing vapor only — not residues) defined in
516.3 shall comply with the applicable provisions of
Article 501 or Article 505, as applicable.
(B) Wiring and Equipment — Vapors and Residues.
Unless specifically listed for locations containing deposits of dangerous quantities of flammable or combustible vapors, mists, residues, dusts, or deposits (as applicable), there shall be no electrical equipment in any spray area as herein defined whereon deposits of combustible residue may readily accumulate, except wiring in rigid metal conduit, intermediate metal conduit, Type MI cable, or in metal boxes or fittings containing no taps, splices, or terminal connections. [33:6.4.2]
(C) Illumination. Illumination of readily ignitible areas through panels of glass or other transparent or translucent material shall be permitted only if it complies with the following:
(1) Fixed lighting units are used as