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.



June 10, 1998

Mr. Al Parro
Pro-Bel Enterprises Limited
1885 Clements Road
Unit 5
Pickering, Ontario L1W 3V4

Dear Mr. Parro:

This is in response to your November 4, 1997, letter requesting clarification of 29 CFR 1910.66. Please accept our apology for the delay in responding. Your scenario and question and our reply follow.

Scenario: Paragraph 1910.66(e)(2)(iii) states: "Tie-in guides required in paragraph (e)(2)(i) of this section may be eliminated if one of the guide systems in paragraph (e)(2)(iii)(A), (e)(2)(iii)(B), or (e)(2)(iii)(C) of this section is provided, or equivalent." An equivalent guide system in which rigged lines are run from the upper roof to the lower roof of a building is intended to stabilize a powered platform permanently dedicated to building maintenance covered by §1910.66. These lines will be designed by a professional engineer licensed in the state of this project and will meet the design criteria of the mullion tracks or stabilization buttons.

Question: Is a request for variance required?

Reply: One acceptable method of demonstrating equivalency of a method of suspending or securing a powered platform, as required in paragraph 1910.66(e)(2)(iii), is to provide an engineering analysis by a registered professional engineer. The analysis should demonstrate that the proposed guide system will provide an equal or greater degree of safety for employees than any one of the other methods specified under paragraph 1910.66(e)(2)(i). This is covered in paragraph 11 of the Advisory Guidelines in Appendix A of 1910.66. Also, the design requirements for each installation should be based on the limitations (stresses, deflections etc.) established by nationally-recognized standards as promulgated by the organizations listed under paragraph 3 of the aforementioned Advisory Guidelines or to equivalent standards. Because 1910.66(e)(2)(iii) allows for an equivalent alternative, a variance is inappropriate in these circumstances (i.e., a variance is not required).

We appreciate your interest in worker safety and health. If we can be of further assistance, please contact [the Office of General Industry Enforcement at (202) 693-1850].


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

[Corrected 10/20/2006]