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.

October 3, 2023

Melissa A. Bailey
Ogletree, Deakins, Nash, Smoak & Stewart, P.C.
1909 K Street NW, Suite 1000
Washington, D.C. 20006

Dear Ms. Bailey:

Thank you for your letter, on behalf of the Utility Line Clearance Safety Partnership (ULCSP), to the Occupational Safety and Health Administration (OSHA) regarding the enforcement of the Electric Power Generation, Transmission and Distribution standard, § 1910.269. Your inquiry concerns § 1910.269(r)(7)(i), which contains specifications for climbing ropes used by employees performing line-clearance tree trimming covered by § 1910.269. This letter constitutes OSHA's enforcement position pertaining only to the requirements discussed and may not be applicable to any requests not delineated within your original correspondence. Your inquiry is paraphrased below, and OSHA's response follows.

Inquiry:

Section 1910.269(r)(7)(i) requires that climbing ropes used by employees working aloft in trees have a minimum diameter of 12 mm (0.5 inch) with a minimum breaking strength (MBS) of 10.2 kilonewtons (2,300 pounds) and that synthetic rope have elasticity of not more than 7 percent. If the following conditions are met, would noncompliance with the ½-inch diameter climbing rope requirement in § 1910.269(r)(7)(i) constitute a de minimis condition:

  1. The rope has a 11.1125 mm (7/16-inch) minimum diameter;
  2. The rope has an MBS of at least 2,300 pounds (or 5,000 pounds if OSHA would prefer);
  3. If synthetic, the rope has an elasticity of no more than 7 percent;
  4. The rope is identified by the manufacturer as suitable for tree climbing;
  5. The rope is used in accordance with the manufacturer's recommendations; and
  6. The employee has been trained in its use?

In support of ULCSP's inquiry, you provided OSHA with a spreadsheet produced by an equipment vendor for the tree care industry that lists examples of 7/16-inch and ½-inch diameter climbing ropes produced by different manufacturers, along with data depicting their MBS and elasticity at a 540-pound load. You also asserted that the existing requirement was based on a prior version of American National Standards Institute (ANSI) Z133 - Safety Requirements for Arboricultural Operations, which adopted the then-industry standard of ½ inch diameter climbing rope.

Response:

De minimis conditions are those where an employer has implemented a measure different from one specified in a standard, that has no direct or immediate relationship to safety or health. One of the factors OSHA considers in determining whether a condition is a de minimis condition is whether an employer complies with a proposed OSHA standard or amendment or a consensus standard rather than with the standard in effect at the time of the inspection, and the employer's action clearly provides equal or greater employee protection. (FOM Chapter 4 -Violations, Sec. VIII. - De Minimis Conditions). This factor is relevant to OSHA's determination here.

ANSI Z133-2017, § 8.2.4, specifies that arborist climbing lines used for moving rope systems (which the ANSI standard defines as a climbing system in which the rope adjustment device advances along a moving climbing line) have a minimum diameter of ½-inch (12.7 mm) and be constructed from synthetic fiber, with an MBS of 5,400 pounds. The consensus standard provides further that the maximum working elongation does not exceed 7 percent at a 540-pound load and that arborist climbing lines be identified by the manufacturer as suitable for climbing.

ANSI Z133-2017, § 8.2.4, also contains an exception to the ½-inch diameter specification. Under that exception, a line of not less than 7/16-inch (11 mm) diameter may be used if the employer establishes such use does not create a safety hazard and the arborist has been instructed in the line's use. Furthermore, the line would need to meet or exceed the specifications for 1/2-inch lines in § 8.2.4 (i.e., the line is made of synthetic fiber with a 5,400-pound MBS and maximum working elongation not exceeding 7 percent at a 540-pound load) and be identified by the manufacturer as suitable for tree climbing.

The conclusion that a de minimis condition exists is fact specific for each case. Based on the information ULCSP provided in this inquiry, and OSHA's review of both ANSI Z133-2017 and prior versions thereof, OSHA considers noncompliance with the ½-inch diameter climbing rope requirement in § 1910.269(r)(7)(i) a de minimis condition if all the following conditions are met:

  1. The rope must have a 11.1125 mm (7/16-inch) minimum diameter;
  2. The rope must be constructed from a synthetic fiber;
  3. The rope must have an MBS of at least 5,000 pounds (24.02 kilonewtons [kN]);1
  4. The rope's maximum working elongation must not exceed 7 percent at a load of 540 pounds (2.402 kN);
  5. The rope must be identified by the manufacturer as suitable for tree climbing;
  6. The rope and other components used in the climbing system must be used in accordance with the manufacturer's instructions;
  7. The employee(s) using the rope must have been trained on and comprehend how to safely use the rope.

This de minimis policy relates to the current versions of § 1910.269(r)(7)(i) and ANSI Z133. OSHA notes that it is considering whether it should promulgate a new Tree Care Operations standard for both general industry and construction work. The proposed rule, if issued, could contain new proposed specifications for climbing ropes (see, e.g., https://www.osha.gov/tree-care/rulemaking, accessed Sept. 21, 2023; https://www.osha.gov/sites/default/files/PIRFA_OSHA_Small_Business_Advocacy_Review_Panel_March_13_2020.pdf, accessed Sept. 21, 2023). This enforcement policy is therefore conditioned on OSHA's full evaluation of the evidence supporting the ANSI Z133 exception to the ½-inch diameter specification in that rulemaking (assuming it goes forward), including input from the public on the exception, after notice and an opportunity to comment. In addition, OSHA notes that the continued validity of this enforcement policy may be affected by a new version of ANSI Z133, which may be finalized in the near future. To this end, the ANSI Z133 committee has released a proposed draft revision of ANSI Z133-2017 for public review and comment (see https://www.isa-arbor.com/Portals/0/Assets/PDF/research/Z133_2024_Clean1.pdf?ver=2023-07-18-110702-663, accessed Sept. 21, 2023).

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 https://www.osha.gov. If you have any questions, please feel free to contact the Directorate of Enforcement Programs at (202) 693-2100.

Sincerely,

Kimberly Stille, Director
Directorate of Enforcement Programs

1Although ANSI Z133-2017 specifies a minimum breaking strength of 5,400 pounds for arborist climbing lines, OSHA’s standard for Personal Fall Protection Systems, § 1910.140(c)(4) requires that vertical lifelines used in personal fall protection systems must have a minimum breaking strength of 5,000 pounds.