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Subchapter 5. Electrical Safety Orders
Group 2. High-Voltage Electrical Safety Orders
Article 36. Work Procedures and Operating Procedures
§2940.15. Grounding For the Protection of Employees.
(a) Application. This section applies to grounding of transmission, and distribution lines and equipment for the purpose of protecting employees. Subsection (f) of this section also applies to protective grounding of other equipment as required elsewhere in this Article.
(b) General. For any employee to work transmission and distribution lines or equipment as deenergized, the employer shall ensure that the lines or equipment are deenergized under the provisions of Section 2940.14 and shall ensure proper grounding of the lines or equipment as specified in subsections (c) through (i) of this section. However, if the employer can demonstrate that installation of a ground is impracticable or that the conditions resulting from the installation of a ground would present greater hazards to employees than working without grounds, the lines and equipment may be treated as deenergized provided that the employer establishes that all of the following conditions apply:
(1) The employer ensures that the lines and equipment are deenergized under the provisions of Section 2940.14.
(2) There is no possibility of contact with another energized source.
(3) The hazard of induced voltage is not present.
(c) Testing. Tests shall be conducted to insure that conductors or equipment have been deenergized before employees install any ground on lines or equipment.
(d) Guards or barriers shall be installed as necessary to prevent contact with another exposed energized conductor or equipment.
(e) Equipotential Zone. Temporary protective grounds shall be placed at such locations and arranged in such a manner that the employer can demonstrate will prevent each employee from being exposed to hazardous differences in electric potential.
NOTE to subsection (e): Appendix E to this Article contains guidelines for establishing the equipotential zone required by this subsection. The Division of Occupational Safety and Health will deem grounding practices meeting these guidelines as complying with subsection (e) of this section.
(f) Protective Grounding Equipment.
(1) Conductor(s) or equipment to be grounded shall be clearly identified and isolated from all sources of voltage.
(2) Protective grounding equipment shall be capable of conducting the maximum anticipated fault current.
(3) Grounding devices shall have a minimum conductance of No. 2 AWG copper.
(4) Protective grounds shall have an impedance low enough so that they do not delay the operation of protective devices in case of accidental energizing of the lines or equipment.
(5) There shall be a minimum of one ground on the conductors or equipment being worked on:
(A) between the place where the work is being done and each possible source of supply,
(B) at the work location, or
(C) as close as practicable to the source of supply.
(6) One of the grounding devices shall be visible to at least one member of the crew unless one of the grounding devices is accessible only to authorized persons.
NOTE to subsection (f): Guidelines for protective grounding equipment are contained in American Society for Testing and Materials Standard Specifications for Temporary Grounding Systems to be Used on De-Energized Electric Power Lines and Equipment, ASTM F 855-09. Guidelines for selecting and installing protective grounding equipment are contained in The Institute of Electrical Engineers Guide for Protective Grounding of Power Lines, IEEE Std 1048-2003.
(g) Connecting and Removing Grounds.
(1) Order of connection. The employer shall ensure that, when an employee attaches a ground to a line or to equipment, the employee attaches the ground-end connection first and then attaches the other end by means of a live-line tool.
(2) Order of removal. The employer shall ensure that, when an employee removes a ground, the employee removes the grounding device from the line or equipment using a live-line tool before he or she removes the ground-end connection.
(h) Additional Precautions. The employer shall ensure that, when an employee performs work on a cable at a location remote from the cable terminal, the cable is not grounded at the cable terminal if there is a possibility of hazardous transfer of potential should a fault occur.
(i) Removal of Grounds for Test. The employer may permit employees to remove grounds temporarily during tests. During the test procedure, the employer shall ensure that each employee uses insulating equipment, shall isolate each employee from any hazards involved, and shall implement any additional measures necessary to protect each exposed employee in case the previously grounded lines and equipment become energized.