437-002-2313 Grounding for the Protection of Employees (1) Application. 437-002-2313 applies to grounding of generation, transmission, and distribution lines and equipment for the purpose of protecting employees. Paragraph (4) of this rule also applies to protective grounding of other equipment as required elsewhere in Division 2/RR. (2) General. For any employee to work transmission and distribution lines or equipment as deenergized, the employer must ensure that the lines or equipment are deenergized under the provisions of 437-002-2312 and must ensure proper grounding of the lines or equipment as specified in paragraphs (3) through (8) below. 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: (a) The employer ensures that the lines and equipment are deenergized under the provisions of 437-002-2312 Deenergizing lines and equipment for employee protection, Division 2/RR. (b) There is no possibility of contact with another energized source. (c) The hazard of induced voltage is not present. (3) Equipotential zone. Temporary protective grounds must be placed at such locations and arranged to will prevent each employee from being exposed to hazardous differences in electric potential. NOTE to paragraph (3): Appendix C to Division 2/RR contains guidelines for establishing the equipotential zone required by this paragraph. Oregon OSHA will deem grounding practices meeting these guidelines as complying with paragraph (3) of this rule. (4) Protective grounding equipment. (a) Protective grounding equipment must be capable of conducting the maximum fault current that could flow at the point of grounding for the time necessary to clear the fault. (b) Protective grounding equipment must have an ampacity greater than or equal to that of No. 2 AWG copper. (c) Protective grounds must 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. (d) While working on circuits deenergized under clearance conditions with multi-phase lines, shorts and grounds must be established at the lowest impedance available. Employees may perform work on one phase of a multi-phase line after establishing an equipotential zone that includes the phase being directly worked on. The phases outside the equipotential zone are to be treated as energized with minimum approach distance observed, unless they become part of the equipotential zone. NOTE to paragraph (4): American Society for Testing and Materials Standard Specifications for Temporary Protective Grounds to Be Used on De-Energized Electric Power Lines and Equipment, ASTM F855-09, contains guidelines for protective grounding equipment. The Institute of Electrical Engineers Guide for Protective Grounding of Power Lines, IEEE Std 1048-2003, contains guidelines for selecting and installing protective grounding equipment. (5) Testing. The employer must ensure that, unless a previously installed ground is present, employees test lines and equipment and verify the absence of nominal voltage before employees install any ground on those lines or that equipment. (6) Grounding must be verified if an employee requests it. (7) Connecting and removing grounds. (a) The employer must 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. For lines or equipment operating at 600 volts or less, the employer may permit the employee to use insulating equipment other than a live-line tool if the employer ensures that the line or equipment is not energized at the time the ground is connected or if the employer can demonstrate that each employee is protected from hazards that may develop if the line or equipment is energized. (b) The employer must 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 they remove the ground-end connection. For lines or equipment operating at 600 volts or less, the employer may permit the employee to use insulating equipment other than a live-line tool if the employer ensures that the line or equipment is not energized at the time the ground is disconnected or if the employer can demonstrate that each employee is protected from hazards that may develop if the line or equipment is energized. (8) Additional precautions. The employer must 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. (9) Removal of grounds for test. The employer may permit employees to remove grounds temporarily during tests. During the test procedure, the employer must ensure that each employee uses insulating equipment, must isolate each employee from any hazards involved, and must implement any additional measures necessary to protect each exposed employee in case the previously grounded lines and equipment become energized. Statutory/Other Authority: ORS 654.025(2) & 656.726(4) Statutes/Other Implemented: ORS 654.001 - 654.295 History: OSHA 3-2015, f. 10-9-15, cert. ef. 1-1-16