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NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.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

June 23, 1997

Mr. Stanley G. Cothrin
Department of Safety and Hygiene
ASARCO Incorporated
3422 South 700 West
Salt Lake City, Utah 84119

Dear Mr. Cothrin:

This is in response to your May 1 letter request for interpretation of the control of hazardous energy (lockout/tagout) standard, 29 CFR 1910.147.

In your letter you stated: paragraph 1910.147(c)(4) requires that a procedure be developed and documented for each particular machine and piece of equipment when more than one hazardous energy source is present. Further you stated: [it] is understood that if only one hazardous energy source is present, and all exceptions of paragraph 1910.147(c)(4) are met, then a single procedure can be developed for all sources that meet this requirement.

This appears to be a misinterpretation of the energy control procedure requirements of paragraph 1910.147(c)(4). Under paragraph 1910.147(c)(4), an employer must develop and document procedures for control of potentially hazardous energy for use by authorized employees. This requirement applies whenever there is one or more hazardous energy sources to which an authorized employee could be potentially exposed when performing servicing and maintenance of machines or equipment. In other words, the requirements of paragraph 1910.147(c)(4) are not triggered by the distinction between a single and multiple sources of hazardous energy.

An employer need not document the required energy control procedure for a particular machine or equipment when all eight elements under the exception in the note following paragraph 1910.147(c)(4)(i) exist. Please note that the second element requires the machine or equipment to have a single energy source that can readily be identified and isolated.

In your letter you asked the following question. Our reply follows.


An employer subject to the requirements of paragraph 1910.147(c)(6) must conduct a periodic inspection of an energy control procedure at least annually. Many workplaces have numerous machines or equipment which require servicing and maintenance that is subject to the requirements of 1910.147. A review of every single procedure on an annual basis would be extremely time consuming. What does the Occupational Safety and Health Administration (OSHA) consider to constitute a satisfactory annual periodic inspection of energy control procedures?


Under the requirements of paragraph 1910.147(c)(6)(i), the employer is required to conduct a periodic inspection of the energy control procedure [required under paragraph 1910.147(c)(4)]. OSHA interprets this to mean that each energy control procedure must be separately inspected at least annually. Also, under the requirements of paragraph 1910.147(c)(6)(i), the periodic inspection must include a review of the employee's responsibilities under the energy control procedure being inspected. OSHA interprets this to mean that there must be a review between an authorized employee designated by the employer as the "inspector" and all other authorized employees (and all affected employees when tagout is used to control hazardous energy), of the employees' responsibilities under the specific energy control procedure being inspected.

See the enclosed copy of OSHA's September 19, 1995 letter to the Law Offices of Keller and Heckman (Mr. Lawrence P. Halprin) which provides further clarification of the periodic inspection requirements.

Please be advised that OSHA information references including lockout and tagout and other letters, clarifying and interpreting safety and health standards, are on the Internet World Wide Web and are accessible via the OSHA home page at OSHA information references, including the aforementioned letters of clarification and interpretation, are also available on CD-ROM which may be purchased from the U.S. Government Printing Office, telephone # (202) 283-3238, using GPO Order #: 729-013-00000-5.

We appreciate your interest in employee safety and health. If we can be of further assistance, please contact the Office of Safety Compliance Assistance, Mr. Ronald J. Davies, telephone # 202 219-8031, extension 110.


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