Cal. Code Regs. tit. 8, § 6547
(b) If such work is contemplated and there is reason to suspect the existence of any of the hazards mentioned in subsection (a), tests shall be made of the atmosphere at the location of the proposed work to determine the presence or absence of these hazards. Additional tests shall be made during the progress of the work to determine whether a safe atmospheric condition still exists.
This order does not prohibit an employee protected by approved respiratory equipment from entering such a hazardous atmosphere.
(c) If tank or reservoir roof plates or sheathing are known to be weak or defective, and it is necessary for employees to go on a roof to determine the extent of the weak and defective parts or to remove them, the following precautions, or substantially equally safe procedure, shall be used:
Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.
1. Amendment of section heading and section and new Note filed 5-8-95; operative 6-7-95 (Register 95, No. 19).