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Subchapter 5. Electrical Safety Orders
Group 2. High-Voltage Electrical Safety Orders
Article 36. Work Procedures and Operating Procedures
Enclosed space. A working space, such as a manhole, vault, tunnel, or shaft, that has a limited means of egress or entry, that is designed for periodic employee entry under normal operating conditions, and that, under normal conditions, does not contain a hazardous atmosphere, but may contain a hazardous atmosphere under abnormal conditions.
(a) General. This section covers enclosed spaces that may be entered by employees. It does not apply to vented vaults if the employer makes a determination that the ventilation system is operating to protect employees before they enter the space.
This section applies to routine entry into enclosed spaces. If, after the employer takes the precautions given in this section and in Section 2943, the hazards remaining in the enclosed space endanger the life of an entrant or could interfere with an entrant's escape from the space, then entry into the enclosed space shall meet the permit space entry requirements of Article 37 of the Construction Safety Orders or Section 5157 of the General Industry Safety Orders.
NOTE to subsection (a): Entries into enclosed spaces conducted in accordance with the permit space entry requirements of Article 37 of the Construction Safety Orders or Section 5157 of the General Industry Safety Orders are considered as complying with this section.
(b) Safe Work Practices.
(1) Written, understandable safe work practices for entry into, and work in enclosed spaces and for rescue procedures shall be developed, implemented, and provided to affected employees.
(2) Safe work practices shall conform to the applicable requirements of this section and shall include provision for the surveillance of the surrounding area to avoid hazards such as drifting vapors from tanks, piping and sewers.
(3) For multi-employer worksites, the procedures shall address how all the affected employers will coordinate their work activities, so that operations of one employer will not endanger the employees of any other employer. If the permit-required confined space requirements of Section 5157 or Article 37 of the CSO or the requirements of Section 8355 apply to one or more of the other employers, then the procedures shall also include coordination with those employers.
(c) Training. Employees, including attendants, shall be trained in the nature of the hazards involved, the necessary precautions to be taken, the use of protective equipment and emergency equipment, the enclosed-space entry procedures, rescue procedures, and safe work practices, including instructions as to the hazards they may encounter.
(d) Attendants. While work is being performed in the enclosed space, an attendant with first-aid training shall be immediately available outside the enclosed space to provide assistance if a hazard exists because of traffic patterns in the area of the opening used for entry. The attendant is not precluded from performing other duties outside the enclosed space if these duties do not distract the attendant from monitoring employees within the space or ensuring that it is safe for employees to enter and exit the space.
NOTE: Section 2943(b)(4) requires an attendant while work is being performed in a manhole or vault containing energized electrical equipment.
(e) Rescue Equipment. Employers shall provide equipment to ensure the prompt and safe rescue of employees from the enclosed space.
(f) Evaluating Potential Hazards. Before any entrance cover to an enclosed space is removed, the employer shall determine whether it is safe to do so by checking for the presence of any atmospheric pressure or temperature differences and by evaluating whether there might be a hazardous atmosphere in the space. Any conditions making it unsafe to remove the cover shall be eliminated before the cover is removed.
NOTE to subsection (f): The determination called for in this subsection may consist of a check of the conditions that might foreseeably be in the enclosed space. For example, the cover could be checked to see if it is hot and, if it is fastened in place, could be loosened gradually to release any residual pressure. An evaluation also needs to be made of whether conditions at the site could cause a hazardous atmosphere, such as an oxygen-deficient or flammable atmosphere, to develop within the space.
(g) Removing Covers. When covers are removed from enclosed spaces, the opening shall be promptly guarded by a railing, temporary cover, or other barrier designed to prevent an accidental fall through the opening and to protect employees working in the space from objects entering the space.
(h) Hazardous Atmosphere. Employees shall not enter any enclosed space while it contains a hazardous atmosphere, unless the entry conforms to Article 37 of the Construction Safety Orders for construction or Section 5157 of the General Industry Safety Orders.
NOTE to subsection (h): See Section 2943(b) for additional requirements on attendants for work in manholes and vaults.
(i) Calibration of Test Instruments. Test instruments used to monitor atmospheres in enclosed spaces shall be kept in calibration and shall have a minimum accuracy of + or - 10 percent.
(j) Testing. Before an employee enters an enclosed space, the air shall be tested with a direct reading meter or similar equipment capable of collection and immediate analysis of data samples without the need for an offsite evaluation. Testing is to determine whether dangerous air contamination, oxygen enrichment and/or an oxygen deficiency, and flammable gases and vapors exist in the enclosed space. The test for flammable gases or vapors shall be performed after oxygen testing to ensure the accuracy of the test for the flammability. The direct reading meter shall be approved for use in such explosive or flammable conditions as required by Section 2540.2. A written record of such testing results shall be made and kept at the work site for the duration of the work. Affected employees and/or their representative shall be afforded an opportunity to review and record the testing results.
(1) Where interconnected spaces are blinded off as a unit, each space shall be tested and the results recorded and the most hazardous condition so found shall govern procedures to be followed.
(2) If dangerous air contamination, oxygen enrichment and/or oxygen deficiency does not exist within the space, as demonstrated by tests, entry into and work within the space may proceed subject to the following provisions:
(A) Testing shall be conducted with sufficient frequency to ensure that the development of dangerous air contamination, oxygen enrichment and/or oxygen deficiency does not occur during the performance of any operation.
(B) If the development of dangerous air contamination, oxygen enrichment and/or an oxygen deficiency is imminent, the requirements prescribed by Article 37 of Construction Safety Orders or Section 5157 of the General Industry Safety Orders shall also apply.
(k) Ventilation and Monitoring. If dangerous air contamination, flammable gases or vapors are detected or if an oxygen deficiency is found, forced-air ventilation shall be used to maintain oxygen at a safe level, to prevent dangerous air contamination, and accumulation of hazardous concentration of flammable gases and vapors. A continuous monitoring program is required to ensure that no increase in air contaminants, flammable gas or vapor concentration above safe levels occurs within in the enclosed space.
(l) Specific Ventilation Requirements. If continuous forced-air ventilation is used, it shall begin before entry is made and shall be maintained long enough for the employer to be able to demonstrate that a safe atmosphere exists before employees are allowed to enter the work area. The forced-air ventilation shall be so directed as to ventilate the immediate area where employees are present within the enclosed space and shall continue until all employees leave the enclosed space.
(m) Air Supply. The air supply for the continuous forced-air ventilation shall be from a clean source and shall not increase the hazards in the enclosed space.
(n) No source of ignition shall be introduced until the implementation of appropriate provisions of this section have ensured that dangerous air contamination due to oxygen enrichment, flammable and/or explosive substances does not exist.
(o) Open Flames.
(1) If open flames are used in enclosed spaces, a test for flammable gases and vapors shall be made immediately before the open flame device is used and at least once per hour while the device is used in the space. Testing shall be conducted more frequently if conditions present in the enclosed space indicate that once per hour is insufficient to detect hazardous accumulations of flammable gases or vapors.
(2) Whenever oxygen-consuming equipment such as salamanders, plumbers' torches or furnaces, and the like, are to be used, measures shall be taken to ensure adequate combustion air and exhaust gas venting.
(p) To the extent feasible, provision shall be made to permit ready entry and exit.
(q) Where it is not feasible to provide for ready exit from spaces equipped with automatic fire suppression systems employing harmful design concentrations of toxic or oxygen-displacing gases, or total foam flooding, such systems shall be deactivated. Where it is not practical or safe to deactivate such systems, the provisions of Section 5144 related to the use of respiratory protective equipment shall apply during entry into and work within such spaces and entry of the space shall be in accordance with Article 37 of the Construction Safety Orders or Section 5157 of the General Industry Safety Orders.