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NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.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

July 28, 1995

Ms. Vicki Chouinard
Honeywell, Inc.
Honeywell Plaza
P.O. Box 524
Minneapolis, MN 55440-0524

Dear Ms. Chouinard:

This is in response to your August 16 letter, requesting interpretation of the control of hazardous energy (lockout/tagout) standard, 29 CFR 1910.147. Specifically, you requested clarification on whether a master key could be used to open individually keyed padlocks provided to an authorized employee for use as his or her personal lockout device. Please accept our apology for the delay in responding.

The aforementioned request for clarification is the subject of the lockout or tagout devices removal requirement at 1910.147(e)(3), that is, "each lockout or tagout device shall be removed from each energy isolating device by the employee who applied the device." When an authorized employee cannot use his or her key either because the employee is not at the facility or because the employee does not have his or her key, a master key or a duplicate key is not an acceptable means for removal of a padlock affixed to an energy isolating device by an authorized employee. When the authorized employee is not available to remove his or her personal padlock, it may be removed using bolt cutters or other equivalent means resulting in destruction of the lock under the direction of the employer as required in the following 1910.147(e)(3) exception.

"When the authorized employee who applied the lockout or tagout device is not available to remove it, that device may be removed under the direction of the employer, provided that specific procedures and training for such removal have been developed, documented and incorporated into the employer's energy control program. The employer shall demonstrate that the specific procedure provides equivalent safety to the removal of the device by the authorized employee who applied it. The specific procedure shall include at least the following elements:

(i) Verification by the employer that the authorized employee who applied the device is not at the facility; (ii) Making all reasonable efforts to contact the authorized employee to inform him/her that his/her lockout or tagout device has been removed; and (iii) Ensuring that the authorized employee has this knowledge before he/she resumes work at that facility".

The employer must be prepared to demonstrate to the Occupational Safety and Health Administration (OSHA), that is, the Compliance Safety and Health Officer (CSHO) during an inspection of the facility, that the aforementioned specific procedures provide equivalent safety to removal of the padlock by the employee who applied it.

Additional requirements governing the use of padlocks and their keys used for 1910.147 applications are as follow. An authorized employee must not perform servicing and maintenance on a machine or equipment after the key to a padlock affixed to an energy isolating device for that machine or equipment is determined to be lost. The lost-key padlock must be removed (in accordance with section 1910.147(e)(3) as discussed above) from the energy isolating device and replaced by another padlock and key. Also, an authorized employee must not affix a lock to an energy isolating device for a machine or equipment and perform servicing and maintenance on that machine or equipment after the key is determined to be lost. These precautions must be taken to ensure that a lost key or another key, that is, a master key or duplicate key, is not used inappropriately. As such, keys and padlocks must be under the exclusive control of the authorized employee to ensure that the safety provided by padlocks when affixed to energy isolating devices is maintained when the authorized employee is performing servicing and maintenance on machines and equipment covered by the 1910.147 standard.

We appreciate your interest in occupational safety and health. If we can be of further assistance, please contact Mr. Ronald J. Davies of my staff, telephone 202-219-8031, extension 110.


John B. Miles, Jr., Director
Directorate of Compliance Programs