Our Clients 
Lockouts Explained 
Lockout Samples 
Terms & Definitions 
Request For Information 

 Products & Services 
Arc Flash  
Evacuation Plans 
Preventive Maintenance 
Military Documentation 
Technical Writing 
Technical Training 
Visual Aids & Illustrations 
Software & Multimedia 
Industrial Signage 

 Other Options 
Contact Us 
EHS Insider 


[ Tutorial ] [ Hot Topics ] [ Case Studies ]
[ LOTO standard ] [ LOTO preamble ] [ Compliance directive ]
[ Selected case law ] [ Selected letters of interpretation ]

Selected Letters of Interpretation

OSHA Standards Interpretation and Compliance Letters

Control of Hazardous Energy Sources (Lockout/Tagout).

  • Record Type: Interpretation
  • Standard Number: 1910.147;1910.333
  • Subject: Control of Hazardous Energy Sources (Lockout/Tagout).
  • Information Date:1991

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


Call Toll Free 888.741.8252 | Español | Français | Deutsch | Português ©2021 St. Claire, inc.