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 https://www.osha.gov.

February 28, 2000

Ms. Gretchen R. Busch
Project Manager
The Resource Effectiveness Development Group
P.O. Box 247
Reynoldsburg, OH 43068

Dear Ms. Busch:

Thank you for your July 10, 1999 letter to the Occupational Safety and Health Administration's (OSHA's) Directorate of Compliance Programs regarding 29 CFR §1910.147 The Control of Hazardous Energy (lockout/tagout). Your scenario, question, and our reply follow.

Scenario: Recently, one of my customers requested a written lockout/tagout program and I ran across some interpretations that I found both insightful and helpful. However, there is one interpretation that has raised some questions. The interpretation that I am referring to is dated July 28, 1995 from John B. Miles to Ms. Vicki Chouinard of Honeywell, Inc.

The specific question is in regard to using a master key on a lock when an authorized employee is not on site. The interpretation states that a master key is not acceptable and a bolt cutter [or equivalent means resulting in the destruction of the lock] must be used to remove the lock. After reviewing the 29 CFR 1910.147(e)(3) reference, I do not see any mention of the use of a master key as being unacceptable, nor conversely, the use of bolt cutters acceptable.

What I have found is that the regulation clearly states that the employer of the authorized employee may remove a lockout device as long as a documented procedure is followed. This procedure, at a minimum, must include: (1) verification by the employer that the [authorized] employee [who applied the device] is not on site; (2) [all] reasonable efforts to contact the authorized employee to inform him or her that the lock has been removed; and (3) the employee is definitely informed of the removal of the lock upon his or her return to work.

Question: Based on the above information and a very specific written procedure, isn't it possible that an employer does have an alternative to bolt cutters as a way to remove lockout devices?

Reply: Bolt cutters, or other device-destructive methods, are not the only permissible means by which to remove a lockout device, if the employer can demonstrate that the specific alternative procedure, which the employer follows prior to removing the device, provides a degree of safety that is equivalent to the removal of the device by the authorized employee who first affixed it.(1) The use of a master key to remove a lockout device would be deemed equivalent (to the removal of the lock by the person who applied it) only if it is performed under the employer's direction and in accordance with the requirements established in 1910.147(e)(3).

Obviously, the "one person, one lock, one key" practice is the preferred means and is accepted across industry lines, but it is not the only method to meet the language of the standard. However, prior to the use of the master key method, specific procedures and training, meeting the §1910.147(e)(3) exception, must be developed, documented, and incorporated into your energy control program. Among the features essential to a compliant master key procedure is a reliable method to ensure that access to the master key will be carefully controlled by the employer such that only those persons authorized and trained to use the master key in accordance with the employer's program can gain access.

Safety is ensured not through the use of a specific removal device, be it a master key or bolt-cutter; rather, it lies in effective procedures, careful training, and procedures designed to ensure accountability. The success of any employer's energy control program, including lockout or tagout device removal actions, depends upon ensuring that its employees follow established, effective procedures, thereby respecting the sanctity of another employee's lockout or tagout device.

Thank you for your interest in occupational safety and health. We hope this provides the clarification you were seeking and apologize for any confusion the earlier document may have caused. The interpretation in this letter supersedes the July 28, 1995 Honeywell, Inc. letter, which is hereby rescinded. As this letter demonstrates, OSHA's re-examination of an issue may result in the clarification or correction of previously stated enforcement guidance. In the future, should you wish to verify that the guidance herein remains current or access the referenced information, you may consult OSHA's website at http://www.osha.gov. If you have any further questions, please feel free to contact the Office of General Industry Compliance Assistance at (202) 693-1850.


Richard E. Fairfax, Director
Directorate of Compliance Programs


FOOTNOTE (1) While your question does not specifically address tagout devices, please be aware that the destructive removal of the tagout device is required by the standard, and there is no equivalent "master key" concept for tagout devices. Tagout device attachment means must be of the non-reusable and non-releasable type. [See subsection 1910.147(c)(5)(ii)(C)(2).] The standard mandates non-reusable tagout devices in order to adequately protect the authorized employee who affixes the tagout device and to prevent other employees from removing the tagout device in a way that is not permitted. (Back to text)