Standard Interpretations - Table of Contents|
| Standard Number:||1910.269|
November 21, 2012
Mr. Lee Hicks
Dear Mr. Hicks:
Thank you for your October 20, 2011, letter to the Occupational Safety and Health Administration (OSHA). You requested clarifications regarding 29 CFR 1910.269, OSHA's standard for the operation and maintenance of electric power generation, transmission, and distribution facilities. This constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any question not delineated within your original correspondence. We apologize for the delay in responding.
Your paraphrased scenarios and questions, and our replies, follow.
Scenario 1: Your utility has established, as a written rule, a minimum approach distance of 4 feet, 0 inches for employee exposure to energized parts on a 25 kV system, regardless of whether that exposure is phase to ground or phase to phase. This distance is greater than the minimum approach distances required by §1910.269, Table R-6. Under Table R-6, the minimum approach distance for a 25 kV system is 2 feet, 4 inches for phase-to-ground exposures, and 2 feet, 7 inches for phase-to-phase exposures. A qualified employee is working on a fixed conductive object, and a portion of the object breaches (is within) your company's established 4-foot, 0-inch minimum approach distance.
Question 1A: Is it a violation of § 1910.269 if a qualified employee who is not wearing rubber gloves and sleeves contacts a grounded, fixed (permanently installed), noncurrent-carrying metal part, such as an equipment bracket or a transformer case, that is located partially within your utility's established minimum approach distance from exposed energized conductors (that is, within 4 feet, 0 inches for 25-kV installations) but outside the electrical component of the minimum approach distances specified in Table R-6?
Response: Paragraph (1)(2) of §1910.269 generally requires the employer to "ensure that no employee approaches or takes any conductive object closer to exposed energized parts than set forth in Table R-6."1 In your scenario, however, because the fixed object is not moving, OSHA does not consider it an object that can be "taken" within a minimum approach distance. Therefore, it is not a violation of §1910.269(l)(2) for the employee to touch the grounded, fixed object, even if it is within (inside) the Table-R-6 minimum approach distance for exposed energized conductors. However, under §1910.269(l)(9), the employer call treat the fixed object as grounded only if the employer first inspects the installation and determines that the part is grounded.2 If the employer does not verify that the fixed object is grounded, the employee must treat it as energized and maintain the Table R-6 minimum approach distance from it (or comply with one of the exceptions to the minimum approach distance requirements in 29 1910.269(l)(2)(i), §1910.269(l)(2)(ii), and §1910.269(l)(2)(iii)).
Question 1B: What if the fixed conductive object, such as a switch bracket, is ungrounded?
Response: As explained in response to Question 1A, if the fixed object is ungrounded, §1910.269(l)(9) requires that it be treated as energized at the highest voltage to which it is exposed. Therefore, under §1910.269(l)(2), employees would need to maintain the Table R-6 minimum approach distance from the ungrounded, fixed object (as well as from the exposed energized conductors) or comply with one of the exceptions to the minimum approach distance requirements in §1910.269(l)(2)(i), §1910.269(l)(2)(ii), and §1910.269(l)(2)(iii)).
Scenario 2: A qualified employee is working on the primary or secondary conductors, or both, of a single-phase transformer that has been isolated from all energy sources by established open points and there is no potential for induced voltage.
Question 2A: Paragraph (n)(2) of §1910.269 provides that before employees call work lines or equipment as deenergized, the lines or equipment must be deenergized and grounded. There is an exception to the grounding requirement for circumstances in which the employer can demonstrate that installation of protective pounds is impracticable. What does OSHA consider to be impracticable such that protective grounding may be omitted for purposes of §1910.269(n)(2)?
Response: Under §1910.269(n)(2), employers generally must ground lines and equipment before employees can work the lines or equipment as deenergized.3 Grounds can be omitted only if the employer can demonstrate either that the installation of a ground is impracticable or that the conditions resulting from the installation of a ground would present greater hazards than work without grounds.
OSHA expects that conditions warranting the absence of protective grounds will be rare. In the preamble to the final rule for the §1910.269 standard, OSHA identified, as an example of conditions in which the use of grounds might be impracticable, the conditions that exist during the beginning stages of work on underground cables where the conductor ends are not yet exposed. 59 FR 4320, 4394 (January 31, 1994). Please note that in any circumstances where grounds are not required under §1910.269(n)(2), the employer still must deenergize the lines and equipment under §1910.269(m), ensure there is no possibility of contact with another energized source, and determine that there is no hazard of induced voltage. If these conditions are not met, the employees must work the lines or equipment energized, following all applicable standards regarding energized work.
Additionally, please note that the "impracticable" exception to the protective grounding requirement relates to feasibility of installing grounding equipment, not to the employer's ability to use a particular grounding method. And, although it might be impracticable to use one type of protective grounds at a particular location, the employer might be able to relocate the grounds or use another method of grounding. For example, bracket grounding4 might be used instead of single-point grounding to provide an equipotential zone for employees.
Question 2B: If the placing of a ground is not impracticable for purposes of §1910.269(n)(2), can employees still work the lines as deenergized if the conditions of §1910.269(n)(2)(i), §1910.269(n)(2)(ii), and §1910.269(n)(2)(iii) are met; that is, if the lines and equipment have been deenergized under §1910.269(m), there is no possibility of contact with another energized source, and the hazard of induced voltage is not present?
Response: Generally, no, unless the employer can demonstrate that the conditions resulting from the installation of a ground would present greater hazards than working without grounds. If the employer cannot show either that placing a protective ground is impracticable or that the conditions resulting from the installation of a ground would pose greater hazards than working without grounds, the employees must work the lines as energized, following all applicable standards regarding energized work, or install protective grounds.
Question 2C: For purposes of §1910.269(n)(2), is there a voltage threshold (for example, under 600 volts) below which the installation of a protective ground is considered inherently impracticable or is otherwise not required?
Response: No, although in some cases it will be impracticable to use certain types of protective grounding equipment on some conductors and equipment below 600 volts. See OSHA CPL 02-01-038, Enforcement of the Electric Power Generation, Transmission, and Distribution Standard (June 18, 2003), Appendix B, Issue 11. Also, please note that employers can deenergize any line or equipment without grounding that line or equipment as long as the employer treats the line or equipment as energized, following all applicable standards regarding energized work.
Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA's requirements are set by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA's interpretation of the requirements discussed. From time to time, letters are affected when the Agency updates a standard, a legal decision impacts a standard, or changes in technology affect the interpretation. To assure that you are using the correct information and guidance, please consult OSHA's website at http://www.osha.gov. If you have further questions, please feel free to contact the Directorate of Enforcement Programs at (202) 693-2100.
Thomas Galassi, Director
1 29 CFR 1910.269(l)(2), Minimum approach distances, states:
The employer shall ensure that no employee approaches or takes any conductive object closer to exposed energized parts than set forth in Table R-6 through Table R-10, unless:
2 29 CFR 1910.269(l)(9), Noncurrent-carrying metal parts, states:
Noncurrent-carrying metal parts of equipment or devices, such as transformer cases 2nd circuit breaker housings, shall be treated as energized at the highest voltage to which they are exposed, unless the employer inspects the installation and determines that these parts are grounded before work is performed. [Return to Text]
3 29 CFR 1910.269(n)(2), General, states:
For the employee to work lines or equipment as deenergized, the lines or equipment shall be deenergized under the provisions of paragraph (m) of [§ 1910.269] and shall be grounded as specified in paragraphs (n)(3) through (n)(9) of [§ 1910.269]. 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 than working without grounds, the lines and equipment may be treated as deenergized provided all of the following conditions are met:
4 "Bracket grounding" is a term for grounding on both sides of the work area. This can be done, for example, to protect employees in insulated aerial lifts working midspan between two conductor-supporting structures. [Return to Text]
Standard Interpretations - Table of Contents|