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(a) The following areas shall be classified as Class I, Division I Locations:
(1) Below grade well cellars, sumps or ditches (see Figures 2 and 6).
(2) Enclosed and inadequately ventilated areas below the derrick floor (see Figure 1).
(3) Enclosed areas containing mud tanks or shale shakers (see Figures 3, 4, 5 and 6).
EXCEPTION: Adequately enclosed areas shall be permitted to be classified as Class I, Division 2 Locations.
(b) The following areas shall be classified as Class I, Division 2 Locations:
(1) Within 10 feet horizontally and 18 inches vertically from the edge of well cellars or other below grade, Class I, Division I Locations.
(2) Within 10 feet radially of the center of the bell nipple in open derricks.
(3) The entire area above the derrick floor in enclosed derricks. (4) Areas adjacent to mud tanks as required in Figures 3 and 4; pits as required in Figure 2; shale shakers as required in Figure 5; or openings as required in Figure 2; in enclosures classified Class I, Division I Location in subsection (a) above.
NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code; and Section 118943(c Health and Safety Code.
1. Editorial correction of NOTE filed 11-2-83 (Register 83, No. 45).
2. Amendment of subsection (b) filed 8-27-86; effective thirtieth day thereafter (Register 86, No. 37).