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(a) Definition. This section covers locations where paints, lacquers, or other flammable finishes are regularly or frequently applied by spraying, dipping, brushing, or by other means; where volatile flammable solvents or thinners are used; and where readily ignitable deposits or residues from such paints, lacquers, or finishes may occur.
(Title 24, Part 3, Section 516-1.)
(b) Hazardous Locations. Classification is with respect to the effects of an exposure to flammable vapors, and in some cases deposits of paint spray residue.
(1) Class I, Division 1 Locations. The following spaces shall be considered Class I, Division 1 locations.
(A) The interiors of spray booths and their exhaust ducts.
(B) Any space in the direct path of spray or any space containing dangerous quantities of air-suspended combustible residue, deposits, vapor or mists as a result of spraying operations more extensive than touch-up spraying and not conducted within spray booths.
(C) For dipping operations, all space within 5 feet in any direction from the vapor source. The vapor source shall be the liquid surface in the dip tank, the wetted surface of the drain board and the surface of the dipped object over either the liquid surface or the wetted surface of the drain board and extending from these surfaces to the floor.
(D) Pits having an opening within Class I, Division 1 and Division 2 locations.
(2) Class I, Division 2 locations. The following spaces shall be considered Class I, Division 2 locations.
(A) For extensive open spraying, all space outside of, but within 20 feet horizontally and 10 feet vertically of the Class I, Division 1 location as defined in Section 2540.9(b)(1) and not separated from it by partitions. See Figure 1.
(B) For spraying operations conducted within a closed top, open face or front spray booth, the space shown in Figures 2 and 3, and the space within 3 feet in all directions from openings other than the open face of front.
The Class I, Division 2 location shown in Figures 2 and 3 shall extend from the open face or front of the spray booth in accordance with the following:
1. If the ventilation system is interlocked with the spraying equipment so as to make the spraying equipment inoperable when the ventilation system is not in operation, the space shall extend 5 feet from the open face or front of the spray booth, and as otherwise shown in Figure 2.
2. If the ventilation system is not interlocked with the spraying equipment so as to make the spraying equipment inoperable when the ventilation system is not in operation, the space shall extend 10 feet from the open face or front of the spray booth, and as otherwise shown in Figure 3.
(C) For spraying operations conducted within an open top spray booth, the space 5 feet above the booth and within the space shown in Figure 3 as a Class I, Division 2 location adjacent to openings.
(D) For spraying operations confined to an enclosed spray booth, the space within 3 feet in all directions from any openings in the spray booth.
(E) For dip tanks and drain boards, and for other hazardous operations, all space beyond the limits for Class I, Division 1 and within 8 feet of the vapor source as defined in (b)(1)(C). In addition, all space from the door to 3 feet above the floor, and extending 20 feet horizontally from the vapor source as defined in (b)(1)(C).
(3) Nonhazardous Locations. Locations utilizing drying, curing, or fusion apparatus and provided with positive mechanical ventilation adequate to prevent formation of flammable concentrations of vapors, and provided with effective interlocks to de-energize all electric equipment (other than equipment approved for Class I locations) in case the ventilating equipment is inoperative, may be classified as nonhazardous.
(Title 24, Part 3, Section 516-2.)
(c) Fixed and Hand-held Electrostatic Spraying Equipment and Powder Coating.
The installation and/or use of fixed and hand-held electrostatic spraying equipment and powder coating shall comply with the applicable provisions of Title 24, Part 3.
Note: The National Electrical Code, 1984 Edition, contains guidelines that are appropriate for determining the type and design of equipment and installations with respect to fixed and hand-held electrostatic spraying and powder coating. The guidelines f this referenced document address electric wiring, equipment and systems installed in hazardous (classified) locations and contains specific provisions for the following: Location of power and control equipment, ventilation, protection from electric shock, protection of high voltage conductors and leads, proper separation of spray heads from materials being sprayed, proper support of materials, proper grounding, guarding and isolation, warning signs and labels, and automatic controls to assure adequate ventilation, minimize shock hazard and preclude arcing in the hazardous location.