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.

July 15, 1997

Mr. George C. Marrs, Jr.
Tyik, Gustafson and Associates, Inc.
407 S. Dearborn
Suite 900
Chicago, IL 60605

Dear Mr. Marrs:

This is in response to your May 6 letter requesting clarification of 1910.66 Powered platforms (permanently dedicated) for building maintenance standard. Please accept our apology for the delay in responding. In your letter, you specifically referenced paragraph 1910.66(f)(5)(ii)(M). With the following exception, this paragraph requires that a fall arrest (vertical lifeline) system be used for employee fall protection if the failure of one of the wire rope or suspension attachment will cause the platform to upset. If a secondary wire rope suspension (for the platform) is used (to prevent the platform from upsetting if one of the wire ropes or attachments of the primary suspension fails), a vertical lifeline is not required provided that each employee is attached to a horizontal lifeline anchored to the platform. Your question and our reply follow.


The safety concern of paragraph 1910.66(f)(5)(ii)(M) is the fall protection of an employee working on an elevated work platform that will upset if one of the wire ropes or suspension attachments fails. Does this preclude the case in which the platform becomes upset and the occupants are tipped out without a suspension rope breaking? In this case the load on the horizontal lifeline would be much greater.


No. Employees on working platforms must be protected by a personal fall arrest system which meet the requirements of Appendix C, Section I and as otherwise provided by 1910.66. Under paragraph (9) of Section I in Appendix C, horizontal lifelines, where used, must be designed, and installed as part of a complete personal fall arrest system, which maintains a safety factor of at least two, under the supervision of a qualified person. A qualified person means one with a recognized degree or professional certificate and extensive knowledge and experience in the subject field who is capable of design, analysis, evaluation, and specification in the subject work, project, or product.

We appreciate your interest in occupational safety and health. If we can be of further assistance, please contact the Office of Safety Compliance Assistance, Mr. Ronald J. Davies, telephone (202) 219-8031, extension 110.


John B. Miles, Jr., Director
Directorate of Compliance Programs