OSHA Safety and Health Regulations for Construction (29 CFR Part 1926) 1926.962: 1926.962 Grounding for the protection of employees

Applies whenever transmission and distribution lines or equipment are grounded to protect employees, whether this subpart requires it or the employer chooses to; paragraph (d) also governs protective grounding of other equipment required elsewhere in the subpart. Before employees treat lines or equipment as deenergized for work, the employer ensures they are deenergized under 1926.961 and properly grounded under (c) to (h). If the employer can show a ground is impracticable, or that grounding would create greater hazards than working without, the lines may be treated as deenergized only when it establishes that they are deenergized under 1926.961, no contact with another energized source is possible, and induced voltage is not a hazard. Temporary protective grounds must be placed and arranged so that the employer can show no employee will face hazardous potential differences; OSHA deems grounding that follows the Appendix C guidelines to comply. Protective grounding equipment must carry the maximum fault current possible at the grounding point for the time needed to clear the fault, have ampacity at least equal to No. 2 AWG copper, and have low enough impedance that protective devices are not delayed if the lines are accidentally energized (ASTM F855-09 and IEEE Std 1048-2003 give guidance). Except where a ground is already installed, employees test and confirm that nominal voltage is absent before putting on any ground. Grounds are attached ground-end first, with the line end then connected by live-line tool; removal takes the line end off first by live-line tool, then the ground end. At 600 volts or less other insulating equipment may be used if the employer ensures the line is not energized at that moment or shows employees are protected if it becomes energized. For work on a cable at a point remote from its terminal, no terminal ground is applied if a fault could transfer hazardous potential. Grounds may be removed temporarily for tests, during which the employer ensures employees use insulating equipment, isolates them from hazards, and takes other measures needed if the previously grounded lines become energized.