Standard Interpretations - Table of Contents
• Standard Number: 1910.66(e)(2)(i); 1910.66(e)(2)(iii)

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

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 m