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Standard Interpretations - Table of Contents
• Standard Number: 1910.147; 1910.147(c)(4)(i)

This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any situation not delineated within the original correspondence.

May 9, 2006

Mr. Kevin Donaghue
Vice President
Aon Risk Services, Inc. of Illinois
200 East Randolph Street
Chicago, IL 60601

Dear Mr. Donaghue:

Thank you for your March 15, 2006, letter to the Occupational Safety and Health Administration's (OSHA) Correspondence Control Unit. You had questions regarding OSHA's Control of hazardous energy (lockout/tagout), 29 CFR §1910.147, standard. Your question and our reply follow.

Question: In regard to exception number 5 — i.e., a single lockout device will achieve a lock-out condition — outlined in 1910.147(c)(4)(i), does the exception still apply if an additional lock is required to isolate an adjoining piece of equipment (i.e., conveyor feeding a hopper of a baler that is being locked out)?

Reply: No, since the addition of another lock on a conveyor and baler system would exceed one lockout device.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. 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 If you have any further questions, please feel free to contact the Office of General Industry Enforcement at 202-693-1850.


Richard E. Fairfax, Director
Directorate of Enforcement Programs

Standard Interpretations - Table of Contents

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