Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

January 29, 1991

Mr. Stephen C. Yohay
Jones, Day, Reavis and Pogue
Metropolitan Square
1450 G Street, N.W.
Washington, D.C. 20005-2088

Dear Mr. Yohay:

This is in response to your letter of November 30, 1990, to Mr. Thomas Seymour, Deputy Director of the Directorate of Safety Standards, regarding 29 CFR 1910.147, Control of Hazardous Energy Sources (Lockout/Tagout).

You expressed interest in a clarification of the Occupational Safety and Health Administration (OSHA) interpretation and met with appropriate representatives of OSHA on December 7, 1990, to discuss Union Carbide's approach to compliance with the standard. During the meeting you displayed a videotape of Union Carbide's group lockout policy and input was freely given to representatives of Union Carbide by our Safety Standards and Compliance Programs staffs in response to all of your questions.

You asked specifically in your letter whether, in a group lockout situation, an employee must himself be performing service or maintenance on de-energized equipment to be eligible to apply a lock or tag for his own protection and/or the protection of others. If only one person is required to perform the servicing or maintenance task, then that person must apply the lock or tag to the energy isolating device. If two or more persons are required for the maintenance or servicing, then group lockout procedures are applicable as described in 29 CFR 1910.147(f)(3) and STD 1-7.3, paragraph H.8.(a. through h.), with detailed discussion and acceptable examples given in Appendix C, paragraph B. The Type A example given on page C-5 of Appendix C calls for each employee performing service or maintenance to apply a personal lock or tag upon each energy isolation device. The Type B, C, and D examples given in pages C-5 and C-6 would allow employees who are not performing the individual servicing or maintenance tasks to place the locks or tags on the energy isolation devices; however, this allowance must be addressed in the employer's written procedures and the procedures must afford the employees a level of protection equivalent to that provided by the use of personal locks or tags. Each servicing/maintenance employee in all cases must be permitted to verify that all energy sources are isolated and to affix a personal lock or tag either on each energy isolation device or on the group lockout device, group lockbox, or comparable mechanism.

During our meeting with you on December 7, 1990, your concern about the interface of the Electrical Safety Related Work Practices standard with the Lockout/tagout was also briefly discussed. Our recommendation was that the written procedures being developed by your client for compliance with the Lockout/Tagout standard should incorporate requirements for compliance with the lockout and tagging portions of the Electrical Safety Related Work Practices standard. The latter standard was written to allow for such combining, and at 29 CFR 1910.333(b)(2) it specifies how this may be accomplished.

Thank you for your interest in improving employee safety and health. If we can provide further assistance, please do not hesitate to contact us.


Patricia K. Clark, Director
Directorate of Compliance Programs