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NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.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

October 24, 2000

Ms. Vernette Francis
P.O. Box 2743
Port Arthur, TX 77643

Dear Ms. Francis:

Thank you for your June 28, 2000 letter to the Occupational Safety and Health Administrations's (OSHA's) [Directorate of Enforcement Programs (DEP)]. You had a specific question regarding group lockout procedures.

Question: "...must a member of other work groups (maintenance, servicing and contractors) be present to verify the effectiveness of the lockout while the primary authorized employee is performing the steps necessary for energy isolation and control?"

Reply: 29 CFR 1910.147(f)(3), Group lockout or tagout, does not require that a member from each work group be present to verify the effectiveness of the lockout/tagout (LO/TO) procedures if the employer has designated a primary authorized employee , with the primary responsibility for a set number of employees working under the group LO/TO device(s). The primary authorized employee must implement and coordinate the LO/TO of hazardous energy sources and verify that the steps taken, in accordance with the specific energy control procedure, have in fact isolated the machine or equipment effectively from the hazardous energy sources. This should be accomplished before the authorized employees participating in the group LO/TO, affix their personal lockout or tagout device to the group LO/TO box and before they perform servicing/maintenance activities.

If the employer elects to assign a primary authorized employee to verify effective energy isolation, each authorized employee participating in the group LO/TO must be informed of their right to verify the effectiveness of the lockout measures and each authorized employee must be allowed to personally verify that hazardous energy sources have been effectively isolated, if they so choose. An authorized employee, who opts to verify the effectiveness of the isolation measures, must perform this verification after affixing his or her personal lockout or tagout device and before performing servicing/maintenance activities.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. Please be aware that the enforcement guidance contained in this response represents the views of OSHA at the time the letter was written based on the facts of an individual case, question, or scenario and is subject to periodic review and clarification, amplification, or correction. It could also be affected by subsequent rule making; past interpretations may no longer be applicable. In the future, should you wish to verify that the guidance provided herein remains current, you may 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]

[Corrected 6/2/2005]