Cal. Code Regs. tit. 8, § 2548.25
(a) Where drilling platforms are not enclosed around the drilling operation, all wiring and equipment within 25 feet of the casing of the well being drilled shall be of the type required for Class I, Division 2, or be installed in enclosed areas supplied with adequate ventilation. The electrical power supply to wiring and equipment within positive pressure ventilated areas shall be arranged to prevent energizing the electrical wiring and apparatus until air pressure has been established, for not less than 2 minutes, and arranged to automatically actuate an audible and visual alarm with a 5-minute shut-down time delay to allow safe operational shutdown prior to de-energizing the wiring and apparatus when the ventilation fails.
Enclosed areas supplied with positive pressure ventilation from a nonhazardous area shall be permitted to be classified as nonhazardous areas, provided no flammable vapor source exists within the enclosed areas.
(b) Special locomotive cables and other equivalent portable cables may be run in cable trays under the following conditions in all locations:
Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code; and Section 18943(c), Health and Safety Code.
1. Editorial correction of Note filed 11-2-83 (Register 83, No. 45).
2. Amendment deleting Title 24 cross reference filed 8-27-86; effective thirtieth day thereafter (Register 86, No. 37).