- Standard Number:
OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.
May 03, 2021
Shannon E. Watts
Transmission, Safety & Skills Training Entergy Services, Inc.
1000 Springridge Road
Clinton, Mississippi 39056
Dear Mr. Watts:
Thank you for your letter to the Occupational Safety and Health Administration (OSHA) regarding an interpretation of the minimum approach distance (MAD) requirements at 29 CFR § 1910.269, Electric Power Generation, Transmission, and Distribution, that may apply when installing protective grounding equipment. This constitutes OSHA’s interpretation only of the requirements discussed and may not be applicable to any question not delineated within your original correspondence. Your question is paraphrased below, and our response follows.
Paragraph (n)(3) of §1910.269 requires “temporary protective grounds” to be placed at such locations and arranged in such a manner as to prevent each employee from being exposed to hazardous differences in electrical potential. OSHA has stated the following, with respect to this requirement:
The word “temporary” in this requirement refers to the fact that the grounds are applied temporarily, while employees are working. Temporary protective grounds may include fixed as well as portable grounds, provided the fixed grounds meet the following conditions:
- Enclosed switches that apply the grounds have a visible indicator to show when the ground has been applied; and
- The grounds are inspected and maintained to ensure that they are fully operational.
Question: If a utility intends to use a combination of fixed and portable grounds to comply with the temporary protective grounds requirement in § 1910.269(n)(3), do employees have to maintain the minimum approach distance (MAD) when installing the portable grounds, after the fixed ground switches have been closed?
Response: In accordance with §1910.269(l)(1)(iii), electric lines and equipment must be considered and treated as energized unless they have been deenergized in accordance with §1910.269(d) or (m). Because of the nature of your question, we assume that the lines or equipment involved are part of a transmission or distribution installation and paragraph (m) applies. According to paragraph (m)(3)(viii), the lines and equipment may be considered as deenergized after the applicable requirements of paragraphs (m)(3)(i) through (m)(3)(vii) have been followed. Paragraph (m)(3)(vii) requires the employer to ensure the installation of protective grounds as required by paragraph (n). As a result of these requirements, the employer must consider the lines and equipment as energized, and must adhere to the MAD requirements in §1910.269(l)(3), until the lines and equipment have been deenergized in accordance with paragraph (m) and grounded in accordance with paragraph (n).1
OSHA’s minimum approach distance provision at §1910.269(l)(3)(i) requires the employer to establish minimum approach distances no less than the distances computed by Table R-3 for ac systems.2 For voltages of 72.5 kilovolts and less, the formulas in Table R-3 require the employer to use the phase-to-phase system voltage. For voltages of more than 72.5 kilovolts, the formulas in Table R-3 require the employer to use the phase-to-ground root mean square (rms) voltage, in kilovolts. If the system voltages exceeds 72.5 kilovolts, the employer may calculate MAD on the basis of either: (1) the system phase-to-ground rms voltage or (2) the maximum phase-to-ground rms voltage that can appear at the worksite if the circuit becomes reenergized after the fixed ground switches have been closed, but before installing any portable grounds that are required to comply with the temporary protective grounds requirement in § 1910.269(n)(3).3
Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA requirements are set by statute, standards, and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov. If you have further questions, please feel free to contact the Directorate of Enforcement Programs at (202) 693-2100.
Patrick J. Kapust, Acting Director
Directorate of Enforcement Programs
 The preamble to the final rule revising §1910.269 notes that:
Sometimes, deenergized lines and equipment become energized. Such energization can happen in several ways, for example, by contact with another energized circuit, voltage backfeed from a customer’s cogeneration installation, lightning contact, or failure of the clearance system outlined in final §1926.961 [the construction counterpart to §1910.269(m)].
(See 79 FR 20510, April 11, 2014.) Thus, until all of the requirements of §1910.269(n) are met, lines and equipment can become, and must be treated as, energized.
 OSHA assumes that the question relates to ac systems only. For dc systems, the employer must use the minimum approach distances specified in Table R-8, based on the maximum line-to-ground voltage of the system.
 See footnotes 1 and 2 in Table R-3 for alternatives that are permitted to be used in lieu of using the formulas in that Table.