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 1, 1998

Mr. Thomas J. O'Shea PE
Entek Engineering, LLP
200 Broadway
Troy, New York 12180

Dear Mr. O'Shea:

This is in response to your letter of July 7, requesting compliance assistance from the Occupational Safety and Health Administration (OSHA) regarding the Powered platforms for building maintenance standard 29 CFR 1910.66. We regret the delay in responding to your inquiry.

Your letter indicated that a building owner desires to clean the windows of a multistory building by using powered platforms in accordance with 1910.66. The design of the building precludes the launching of the powered platform from the uppermost level. Therefore, it is necessary to ground rig the platform from lower levels to structural outriggers at the top. The building has some facades that will have to be rigged at heights up to 346 feet.

As you are aware, 1910.66(f)(3)(ii)(A) sets suspension height limits for transportable outriggers at 300 feet above a safe surface, and references the tie-in guides in 1910.66(e)(2) of the standard. However, OSHA would consider it a de minimis violation if the building and equipment installation is designed by a registered professional engineer demonstrating that the proposed method of suspension and securing of the powered platform will provide an equal or greater degree of safety for employees than one of the methods specified in the standard; the employer provides some mechanical means, such as mechanical winches, to raise and lower cable, lifelines, and wire rope during rigging installations; powered platforms are not rigged or operated in winds in excess of 25 miles per hour; the facade is provided with curtain wall mullion tracks for platform engagement and stabilization; and all other applicable 1910.66 provisions are met. De minimis violations are violations of standards which have no direct or immediate relationship to safety or health and are not included in citations. When an employer complies with the clear intent of the standard but deviates from its particular requirements in a manner that has no direct or immediate relationship to employee safety and health. These deviations may involve distance specifications.

Thank you for your interest in occupational safety and health. If we can be of further assistance, please contact Wil Epps of my staff at (202) 219-8041.


Richard Fairfax, Acting Director
Directorate of Compliance Programs