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 http://www.osha.gov.

January 31, 2013

Ms. Michele Mihelic
American Wind Energy Association
1501 M St. NW, Suite 1000
Washington, D.C. 20005

Dear Ms. Mihelic:

Thank you for your October 26, 2011, letter to the Occupational Safety and Health Administration (OSHA). Your letter included a number of recommendations regarding a request that OSHA had received for a letter of interpretation (LOI) concerning compliance with 29 CFR §1910.27, Fixed ladders, as it applies to fixed ladders inside power-generating wind turbine towers. These ladders, which can be as tall as 300 feet, provide access for workers to service equipment in the nacelle and other "uptower" portions of the turbine. However, it was brought to our attention that because the wind turbine towers have flanges protruding into the climbing space of the fixed ladder, the climbing-side clearance is in some cases reduced to 18 inches. This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any questions not delineated within your original correspondence. We apologize for the delay in our response.

29 CFR §1910.27(c)(1) states:

Climbing side. On fixed ladders, the perpendicular distance from the centerline of the rungs to the nearest permanent object on the climbing side of the ladder shall be 36 inches for a pitch of 76 degrees, and 30 inches for a pitch of 90 degrees (fig. D-2 of this section), with minimum clearances for intermediate pitches varying between these two limits in proportion to the slope, except as provided in subparagraphs (3) and (5) of this paragraph.

29 CFR §1910.27(c)(7) partially states:

There shall be not [sic] protruding potential hazards within 24 inches of the centerline of rungs or cleats; any such hazards within 30 inches of the centerline of the rungs or cleats shall be fitted with deflector plates placed at an angle of 60 degrees from the horizontal...

You note in your letter that flanges in wind turbine towers may reduce clearance on the climbing side of a fixed ladder to less than 30 inches, and may create a protruding hazard (to workers who are ascending or descending) between 24 to 30 inches on the climbing side of the fixed ladder. However, pursuant to 29 CFR § 1910.27(c)(7), use of deflector plates, placed at an angle of 60 degrees from the horizontal will achieve compliance with the standard. An illustration of the proper placement of deflector plates can be found at 29 CFR § 1910.27 figure D-5.

It has also been brought to our attention that a letter dated October 23, 2003, from John Miles (former Regional Administrator of OSHA's Region VI office) to Mr. Patrick K. Murphy of LEI Lee Engineering, Incorporated, exempted from compliance ladders such as those found in wind turbines. The letter referenced ANSI A-14.3, 1992, and stated that "paragraph 1-5.1 would exempt compliance for this type of structure." The letter also stated, "As OSHA standard 1910.27 does not address the application and scope of the standard, we defer to ANSI A-14.3 to justify our decision."

To clarify our position, ladders found in wind turbine generators installed in the United States must be designed and constructed to comply with 29 CFR §1910.27, as well as any other applicable OSHA standards. 29 CFR §1910.269(h), which also applies to wind power generating facilities, specifically requires that the ladders used at power generation facilities such as wind turbines comply with OSHA Subpart D requirements. Please note LOIs issued by the Regional Offices are superseded by the National Office LOIs. The Directorate of Enforcement Programs at OSHA's National Office normally issues LOIs, and such interpretations are generally posted on OSHA's web site to reflect OSHA's current policy on a given topic. We ask that you clarify with your members that Subpart D, including fixed ladder requirements, applies to wind power generating facilities.

If a wind energy employer does not meet a particular OSHA standard and implements alternative methods that provide equivalent employee protection, the employer may request a variance from that standard, or a portion of that standard, as authorized by section 6(b)(6)(A) of the OSH Act. The employer would need to file with OSHA a written variance application containing the information specified in paragraph 1905.10(b). The completed and signed variance application should be addressed to the Assistant Secretary for Occupational Safety and Health, U.S. Department of Labor, but sent under cover addressed as follows:

U.S. Department of Labor/OSHA
Office of Technical Programs and Coordination Activities
Room N3655
200 Constitution Avenue, NW
Washington, D.C. 20210

The variance application can also be faxed to (202) 693-1644 or sent electronically to VarianceProgram@dol.gov.

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
Directorate of Enforcement Programs