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Home » Lockout Resources » OSHA Documentation » Letters of Interpretation

Letters of Interpretation

The following are select letters of interpretation pertinant to the 29 CFR 1910.147 Explained, Lockout/Tagout Hot Topics and Interactive Case Studies sections available on this site.

NOTE: OSHA requirements are set by statute, standards and regulations. OSHA's interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. The letters constitute OSHA's interpretation of the requirements discussed. Note that OSHA's enforcement guidance may be affected by changes to OSHA rules. Also, from time to time OSHA updates the guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

1997, June 23 - Clarification of the electric power generation, transmission, and distribution standard.

Standard: 29 CFR 1910.269

Relevance: Energy control procedures 29 CFR 1910.147(c)(4)(i); periodic inspection 29 CFR 1910.147(c)(6)(i).

June 23, 1997

Mr. Gregory C. Bird
Clean Harbors Environmental Services, Inc.
32 Bask Road
Glenmont, NY 12077

Dear Mr. Bird:

This is in response to your September 18, 1996 letter requesting a clarification of the electric power generation, transmission, and distribution standard, 29 CFR 1910.269. Please accept our apology for the delay in responding. Specifically, you asked whether paragraph 1910.269(a)(1)(i)(D) applies to hazardous waste cleanup and/or industrial cleanup activities performed by a Contractor at electric power generation, transmission and distribution facilities.

Cleanup operations at electric power generation, transmission, and distribution facilities are not covered by 1910.269, unless one of the following conditions is met:

  • The operation involves a fuel or ash handling installation, a water or steam installation, or a chlorine or hydrogen installation; or
  • The operation is performed in rooms or spaces that contain exposed energized parts or electric power generation, transmission, or distribution equipment.

Electric power generating stations and transmission and distribution substations typically have areas containing Energized electric lines and equipment. Unless the energized lines or equipment are guarded sufficiently, it is unsafe for unqualified persons to enter these spaces.

With exceptions, electric power generating stations and transmission and distribution substations are restricted to entry by qualified persons. Paragraphs 1910.269(u)(4)(i)(A) through (C) and 1910.269(v)(4)(i)(A) through (C) set forth the conditions for spaces within substations and generating stations, respectively, under which unqualified persons may not enter.

Employers may train employees as qualified employees for the purpose of entering and working within restricted areas of generating stations and transmission and distribution substations. While the training for these employees must meet paragraph 1910.269(a)(2)(ii), such training need not be as comprehensive as the training provided normally to a qualified electrical worker. These "qualified" (non-electrical) employees must have the following training:

  • They must know what is safe to touch and what is not safe to touch in the specific areas they will be entering (paragraph 1910.269(a)(2)(ii)(A));
  • They must know what the maximum voltage of the area is (paragraph 1910.269(a)(2)(ii)(B));
  • They must know the minimum approach distances for the maximum voltage within the area (paragraph .269(a)(2)(ii)(c)); and
  • They must be trained in the recognition and proper use of electrical protective equipment that will be used to provide protection for them and in the work practices necessary for performing their specific work assignments within the area. Only fully qualified electrical employees may install electrical insulating equipment on energized parts. (See the definition of "qualified employee (qualified person)" under paragraph 1910.269(x)).

Until these "qualified employees" have demonstrated proficiency in the work practices involved, they are considered to be employees undergoing on-the-job training and must be under the direct supervision of a qualified employee (qualified person) at all times. According to the definition of "qualified employee (qualified person)," the employee also must have demonstrated an ability to perform the work safely at his or her level of training. It is expected that an orientation familiarizing the employee with the safety fundamentals given here will be conducted before an employee undergoing training is allowed to enter a restricted area.

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

1996, October 29 - Consultants performing Lockout/Tagout periodic inspections.

Standard: 29 CFR 1910.147

Relevance: Performing periodic inspections by an Authorized Employee 29 CFR 1910.147(c)(6)(i)(A).

October 29, 1996

Mr. Stephen M. Mabley, MS, CIH
Director of Safety and Health
11933 Tech Road
Silver Spring, MD 20904

Dear Mr. Mabley:

This is in response to your letter of November 21, 1995, addressed to Ms. Patricia Clark, former Director of this Directorate. In your letter, you requested clarification with regard to the applicability of the Lockout/Tagout Standard, 29 CFR 1910.147, to inspections conducted by authorized employees. Please accept our apologies for the delay in responding to you.

In your letter, you inquired whether it is the intent of OSHA by stating that "an Authorized Employee" shall conduct periodic inspections in the Lockout/Tagout Standard, to preclude consultants and other third parties from conducting required periodic inspections and audits of a company's Energy Control Program. Pursuant to 1910.147(c)(6)(i)(A), a periodic inspection must be performed by an authorized employee. For the purpose of complying with the intent of this standard, authorized employee means a qualified person whom the authority and responsibility to perform a specific Lockout or Tagout inspection has been given by the employer. A qualified person is a person who has been trained and has demonstrated proficiency, in Compliance with 1910.147(c)(7), to perform Servicing and Maintenance on the machine or equipment to be inspected.

Therefore, please note that the function of conducting periodic inspections by consultants would meet the above criteria for the purpose of complying with the Lockout/Tagout Standard requirement.

Thank you for your inquiry. If you need further assistance, please contact the Office of General Industry Compliance Assistance at (202) 693-1850.


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

1996, October 2 - Food Inspectors Lockout/Tagout Procedures.

Standard: 29 CFR 1910.147

Relevance: Group Lockout/Tagout 29 CFR 1910.147(f)(3).

October 2, 1996

Mr. William J. Hudnall
Deputy Administrator for Administrative Management
U.S. Department of Agriculture
Food Safety Inspection Service Administrative
Management Room 347E
J.L. Whitten Federal Building
1400 Independence Avenue, S.W.
Washington, D.C. 20250

Dear Mr. Hudnall:

This is in response to your September 11 letter requesting that the Occupational Safety and Health Administration (OSHA) review four documents the U.S. Department of Agriculture/Food Safety Inspection Service (FSIS) believes will bring their agency into Compliance with the OSHA Standard, 29 CFR 1910.147, The control of Hazardous Energy (Lockout/Tagout). These documents are:

  • the June 19, 1996, FSIS Directive 4791.11, entitled, "Lockout/Tagout Safety Awareness Assessment Procedures,"
  • the booklet entitled, "Lockout/Tagout Lesson Plan for Inspectors,"
  • the training video, "U.S.D.A. Lockout/Tagout" dated 5/96, and
  • the booklet, "Lockout Tagout Pocket Guide" published and distributed by Genium Publishing Corporation, Schenectady, NY.

OSHA does not accept FSIS's use of the aforementioned documents to delegate its responsibility for the safety and health to its employees or to on-site employers (and their employees) at facilities undergoing FSIS required inspections. Under the Lockout/Tagout Standard, FSIS, as an employer, must provide for the safety and health of its employees when performing inspections (which are considered Servicing and Maintenance activities) at worksites. Also, when FSIS employees are engaged in inspection activities covered by the Lockout/Tagout Standard, the on-site employer must comply with paragraph 1910.147(f)(2).

OSHA believes that FSIS and the onsite employer can meet their responsibilities under the standard by establishing a joint Energy Control Program that incorporates the group Lockout or Tagout provisions under paragraph 1910.147(f)(3). Supplemental group Lockout/Tagout guidelines are the subject of Appendix C, OSHA Instruction STD 1-7.3 (copy enclosed). Appendix C identifies group lockout or tagout scenarios. In each of these scenarios, Servicing and Maintenance personnel use an Energy Control Procedure that affords employees a level of protection equivalent to that provided by the implementation of a personal lock or tag. Each employee, considered an Authorized Employee as defined under paragraph 1910.147(b), has exclusive control of energy isolating devices during servicing and maintenance of machines or equipment.

Enclosed are our specific review comments on each document provided to us. We recommend that FSIS revisit their belief that on-site employers should be responsible for the safety of FSIS inspectors while they are preforming pre-operational sanitation inspections. We request that FSIS immediately discontinue the implementation of their FSIS Directive 4791.11 and their training package. This program has created undue concern to your customers, confusion to FSIS inspectors, and increased complaints to OSHA.

We request that the agency prepare an abatement action plan for those locations (see enclosed list) that have received OSHA Notices of Unsafe or Unhealthful Working Conditions and/or OSHA Notices of Failure-to-Abate Alleged Violations of the Lockout/Tagout Standard. This plan should be submitted to OSHA by October 25, 1996. Please contact my office at [(202) 693-2122] should you have any questions.


John E. Plummer, Director
Office of Federal Agency Programs

1995, May 24 - Clarification concerning the Electric Power Generation, Transmission, and Distribution standard.

Standard: 29 CFR 1910.147

Relevance: Provides clarification of the Electric Power Generation standard 29 CFR 1910.269; Tagout devices and their means of attachment 29 CFR 1910.147(c)(5)(ii)(C)(2) and 1910.269(d)(3)(ii)(D); requirements for Lockout and tagout devices (c)(5)(ii)(D) and 1910.269(d)(3)(ii)(E).

May 24, 1995

Mr. Blair M. Brewster
Box 25
West Port Bay Road
Wolcott, NY 14590-0025

Dear Mr. Brewster:

This is in response to your July 30, 1994, letter requesting information and clarification concerning the Electric Power Generation, Transmission, and Distribution standard, 29 CFR 1910.269. Please accept our apology for the delay in responding.

As you requested in your letter, a copy of the stay on the enforcement of some of the requirements contained in the aforementioned electric power generation standard published in the Federal Register (FR), Volume 59, Number 125, on Thursday, June 30, 1994, is enclosed for your use. Please note that the stay was in effect until November 1, 1994. As of November 1, the electric power generation standard has been and continues to be fully in effect except that paragraph (a)(2) on training became effective January 31, 1995, and paragraph (v)(11)(xii) of the 1910.269 standard concerning coal-handling operations which may produce a combustible or flammable atmosphere was stayed until February 1, 1996.

Under 1910.147(c)(5)(ii)(C)(2) and 1910.269(d)(3)(ii)(D), a Tagout device and its means of attachment must be substantial enough to prevent inadvertent or accidental removal. Also under these paragraphs, the means of attachment, not the Tagout device itself, must be of a non-reusable type, attachable by hand, self-locking, and non-releasable with a breaking strength of no less than 50 pounds (22.68 kg) and must have the general design and basic characteristics of being at least equivalent to a one-piece, all environment-tolerant nylon cable tie.

Under 1910.147(c)(5)(ii)(D) and 1910.269(d)(3)(ii)(E), a Lockout and a Tagout device must be identifiable, that is, indicate the identity of the employee applying the device. The "lockout tag" described in your letter could be read as an informational tag accompanying a Lockout Device, for example, as required by the lock and tag provisions of 1910.333(b)(1)(iii). Such informational tags are not required specifically by 1910.269(d).

We appreciate your interest in employee safety and health. If we can be of further assistance, please contact Mr. Ronald Davies of my staff, telephone 202-219-0831, extension 110.


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

1994, August 12 - Label Tagging Devices.

Standard: 29 CFR 1910.1030(a); 29 CFR 1910.1030(b); 29 CFR 1910.1030(c)(2)

Relevance: Discusses Energy Control Procedure 29 CFR 1910.147(c)(4); work on cord and plug (a)(2)(iii)(A); normal production operation (a)(2)(ii) Exception; when service and Maintenance work is covered during normal production (c)(4); specific procedures required for the control of Hazardous Energy (c)(4)(ii); and electrical safety-related work practices 1910.333(b)(2).

August 12, 1994

SUBJECT: Label Tagging Devices

This is in response to your memo of January 24, requesting an interpretation of the applicability of the bloodborne pathogens standard to employees in the garment industry and to the frequent needlestick-like occurrences when using tag attachment guns. We apologize for the delay in this response.

The bloodborne pathogens standard addresses the broad issue of occupational exposure to blood and other potentially infectious materials and is not meant solely for employees in health care settings. Since there is no population that is risk free for human immunodeficiency virus or hepatitis B virus infectivity, any employee who has occupational exposure to blood or other potentially infectious material is included within the scope of this standard. While employees in the garment industry may not be generally considered to have occupational exposure, it is the employer's responsibility to determined which job classifications of specific tasks and procedures involve occupational exposure. The definition of occupational exposure means "reasonably anticipated skin, eye, mucous membrane, or parenteral contact with blood or other potentially infectious materials that may result from the performance of an employee's duties."

The situation which is brought to OSHA's attention involves certain employees in the garment industry who use tag attachment guns (a device which puts the price tags onto garments); there are numerous manufacturers of these devices. The procedure used with these guns is common in the industry and occurs across the country, and employees are being stuck on a regular basis; it appears to be a recognized hazard in the industry. In other words, not only is there a potential for the employees to be stuck, there is actual exposure on an anticipated level. The issue of concern relating the bloodborne pathogen standard is that these needle guns can retain blood in the hollow needle and on the tool. The needle itself, which actually penetrates the skin, would be reasonably anticipated to involve the presence of blood or other potentially infectious material. When guns are exchanged between employees, e.g., during shift changes, the result is a potential transmission of bloodborne pathogens.

Corrected 01/07/2009

1993, June 14 - Applicability of the Machine Guarding and Lockout/Tagout standards to printing presses.

Standard: 29 CFR 1910.1030(a); 29 CFR 1910.1030(b); 29 CFR 1910.1030(c)(2)

Relevance: Applies to 29 CFR 1910.147; 29 CFR 1910.212; and 29 CFR 1910.219 in normal production operations of printing presses and discusses 29 CFR 1910.147(a)(2)(ii), an exception.

June 14, 1993

SUBJECT: Applicability of the Machine Guarding andLockout/Tagout standards to printing presses.

The attached letter of September 16, 1992 to Mr. John Runyan of the Printing Industries of America, Inc. (included below) provides interpretations and clarifications of 29 CFR 1910.147, 1910.212 and 1910.217 as they apply to printing presses only. This letter has been misinterpreted to cover binding and finishing equipment in addition to printing presses. Apparently, this misinterpretation was caused by referencing the use of controls described in ANSI B65.1 for printing press drives and also described in ANSI B65.2 for binding and finishing systems. Similar interpretations and clarifications with respect to binding and finishing systems will be addressed when requested. This request is anticipated in the near future.

Please send a copy of this letter to State Plan States. A copy of this memorandum and the attached letter will be incorporated in OSHA's Computerized Information System (OCIS).

Attachment [-- September 16, 1992 letter to Mr. John Runyan of the Printing Industries of America, Inc. (included below)]

May 3, 1993

Mr. Brian J. Bobal
Director of Safety and Health
Graphic Communication International Union
1900 L Street N.W.
Washington, D.C. 20036

Dear Mr. Bobal:

This is in response to your March 23 letter requesting clarification on the scope of workplace coverage intended by our September 16, 1992 letter to Mr. John Runyan of the Printing Industries of America, Inc. In that letter, OSHA explained its interpretation of the applicability of the Lockout-Tagout standard, to printing presses. (Copy enclosed)

As clearly indicated in the first paragraph, the aforementioned letter interprets and clarifies 29 CFR 1910.147, 1910.212 and 1910.219 as those OSHA standards apply to printing presses. Apparently, confusion was caused by the reference (in our letter to Mr. Runyan) to OSHA and ANSI standards relating to the design of printing presses, and of binding and finishing systems and their respective control equipment (ANSI B65.1 and B65.2) on pages 1 and 3 of the enclosed letter.

We will provide our field office with copies of this letter to inform them of this potential problem. Thank you for your interest in occupational safety and health. If we can be of further assistance, please contact us.


Raymond E. Donnelly, Director
[Office of General Industry Enforcement]

Corrected 4/27/2004

1992, September 16 - Printing Presses: requirements for normal production and servicing operations.

Standard: 29 CFR 1910.147); 29 CFR 1910.212; 29 CFR 1910.219

Note: Additional clarification of this issue is contained in the June 14,1993 Regional Administrator's Memorandum (included above).

September 16, 1992

Mr. John Runyan
Director of Political Affairs
Printing Industries of America, Inc.
100 Dangerfield Road
Alexandria, Virginia 22314

Dear Mr. Runyan:

This is in further response to your letters of August 13, 1991 and January 3, 1992, requesting interpretation and clarification of Occupational Safety and Health Administration (OSHA) standards at 29 CFR 1910.147, 1910.212, and 1910.219 as they apply to printing presses which function under two separate modes of operation. One operational mode occurs when the equipment is used in normal production operations and the OSHA standards on machine guarding apply. The other mode occurs when the equipment is being serviced and maintained and the OSHA standard on the control of Hazardous Energy (Lockout/Tagout) at 1910.147 applies.

From the time of your meeting in December 1991 with former Assistant Secretary Scannell, members of my staff have conducted a more in-depth review of the issues you raised, including points on which apparent conflicts existed, especially those involving the performance of press tasks requiring main drive motion, i.e., cleaning plates and lubricating cylinders, replacing blankets and plates, etc. During the meeting, several ANSI and OSHA standards which cover essential aspects of safe printing press and binding equipment operation were discussed. These standards relate to the design of printing presses, binding and finishing systems and their respective control equipment (ANSI B65.1 and B65.2), guarding during normal production operations (OSHA 1910 Standards, Subpart O), as well as Lockout/Tagout (29 CFR 1910.147). During that meeting, the specific standards of Subpart O, also applicable to printing presses, were likewise discussed. These related to general machine guarding requirements (29 CFR 1910.212) and to mechanical power-transmission apparatus (29 CFR 1910.219).

Since these discussions were intended to help clarify the interpretation of these OSHA standards with respect to their application to printing presses, a summary of the salient points is presented in the following paragraphs. Also, in the enclosure to this letter, the applicability of the OSHA standards 29 CFR 1910.147, 1910.212, and 1910.219, is discussed further.

The variety of printing presses into which different technologies, spanning many years, are incorporated requires that each machine or piece of equipment be analyzed to determine the type of operational modes being conducted, the type of safeguarding used to protect employees during those operational modes and the need for additional safety measures to ensure Compliance with OSHA safety standards at 29 CFR 1910.147, 19190.212, and 1910.219.

The machine guarding standards in Subpart O of the general industry standards apply to the safeguarding of all machines, including printing presses. Specifically, 29 CFR 1910.212 applies to the safeguarding of all machines, and 29 CFR 19190.219 deals with the safeguarding of power transmission apparatus. These standards require safeguarding of machines and equipment to preclude employee injury during normal production operations, that is, when a machine or piece of equipment is being used to perform its intended production function. (See the definition of normal production operation in 1910.147(b)).

On the other hand, the OSHA standard for the control of Hazardous Energy (Lockout/Tagout) requires the safeguarding of machines and equipment whenever Servicing or Maintenance is being performed. This safeguarding normally consists of stopping the machine or equipment, isolating it from its Energy Source(s), locking or tagging out the energy isolating devices, relieving or releasing any stored or residual energy and then verifying that the machine or piece of equipment is safe to work on. All safeguarding activities must be conducted in accordance with procedures developed and documented by the employer for the purpose.

At times, however, OSHA recognizes that some minor Servicing, that is, servicing which must be conducted frequently, may have to be performed during normal production operations, and a Lockout/Tagout exception is allowed. In a note following paragraph 29 CFR 1910.147(a)(2)(ii), this exception is stated:

"Minor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations, are not covered by this standard if they are routine, repetitive, and integral to the use of the equipment for production, provided that the work is performed using alternative measures which provide effective protection (See Subpart O of this Part)."

In the printing industry, we understand that the term "minor Servicing" includes, among others, tasks such as clearing of certain types of paper jams; minor cleaning, lubricating and adjusting operations; certain plate and blanket changing tasks; and, in some cases, paper webbing and paper roll changing. Generally speaking, "minor servicing" is considered to include those tasks involving operations which can be safely accomplished by employees and where extensive disassembly of equipment is not required. Such tasks will be identified through the hazard analysis required by the Lockout/Tagout Standard.

In order to perform Maintenance or Servicing, in which an employee bypasses guards which are required by either 1910.212 or 1910.219, or otherwise becomes exposed to the hazards of machine start-up or to the unexpected release of Hazardous Energy, the OSHA Lockout/Tagout Standards apply. If no such exposure occurs (either because of the methods in which the minor servicing is performed or because special tools, techniques, or other protection is used), Lockout/Tagout is not required, provided the employer uses alternative measures which enable an employee to perform minor servicing without being exposed to a hazard. Under no circumstances is an employee ever permitted to place any part of his or her body within a hazardous area, such as the point of operation, while the equipment is running or Energized (and alternative measures have not been taken), or around power transmission apparatus.

During minor Servicing, an employer is considered to have met the requirement for providing effective alternative protection by the use of special tools or techniques. Effective alternative protection may not include, by themselves, simple pushbuttons, selector switches, and other control circuit type devices which lack a control logic such as an interlocked arrangement which provides a single operator with exclusive control. One such method which does appear to offer effective alternative protection is the inch-safe-service technique used for the main drive control. This technique is consistent with the use of controls specified in the ANSI standards B65.1 and B65.2 for web and sheet-fed printing presses and binding and finishing equipment respectively for which, as a minimum, a stop/safe/ready function must be available at designated control stations. Limiting some control stations to the "inch" function only is not permitted. Also, the stop/safe/ready switch must not serve as the Lockout disconnect when lockout is performed. A brief summation of the essential elements of that procedure together with the observance of certain safe work practices is as follows:

  • Before any minor servicing is performed, the machine must be stopped, and its drive control must be on STOP/SAFE. Servicing and/or maintenance as defined in 29 CFR 1910.147(b) must not be conducted when the components of the machine are moving.
  • Consistent with the requirements contained in 29 CFR 1910.147(f)(1) for testing or positioning a machine during servicing, procedures to inch a machine require all employees be positioned so that they are not endangered by the re-energization or startup of the machine. In addition, all tools or other implements used during the servicing must be positioned so that no hazard is created for employees. On presses attended by more than one operator or when it is possible for another employee to enter the frame or be obscured from view of the operator, suitable safety alerting signals must be employed.
  • By use of the INCH control, the components of the machine are moved to their desired position. Immediately thereafter the drive control is placed on SAFE by each employee working in a hazardous area before beginning or resuming the minor servicing.
  • Steps (b) and (c) are repeated as necessary until the minor servicing is completed.

When minor Servicing is conducted and the use of the STOP/SAFE drive control is the method of safeguarding employees, the controls to make READY, to INCH, and to START the machine must be under the exclusive control of the authorized person(s) who is/are performing the servicing. If there is a likelihood that the START or INCH controls can be inadvertently activated by any employee, including the one performing the minor servicing, it is necessary that the permissive period be immediately canceled by depressing the STOP/SAFE push button, and not wait for the conclusion of the permissive period to conduct the minor servicing. The STOP/SAFE control used for the inch-safe-service procedure shall be designed and installed to preclude energization or startup of the equipment by any other control until all SAFE's are canceled.

When more than one employee performs a particular Servicing or Maintenance operation on a machine or equipment, the servicing or maintenance generally is not considered minor in nature, and the machine or equipment must be locked out or tagged out in accordance with 1910.147. However, if two or more employees perform separate servicing operations on a machine or equipment at the same time, the combined servicing operation may be considered minor servicing only when each separate servicing operation is routine, repetitive and integral to normal production operations, and when alternative effective protection is provided for the servicing employees. Alternative effective protection means:

  • Servicing is conducted when the machine or equipment is stopped, and
  • Each servicing employee has continuous, exclusive control of the means to start the machine or equipment, and
  • Safeguarding is provided to each servicing employee to prevent exposure from the release of harmful, stored, or residual energy.

The electrical standards at 29 CFR 1910 Subpart S contain requirements for employee safety relative to electrical hazards in the workplace. Paragraph 1910.332(a) requires that employees, who service machines or equipment and who face a risk of electrical shock or other electrical hazards that are not reduced to a safe level by the electrical installation requirements of sections 1910.303 through 1910.308, must be trained in electrical safety-related work practices, as required by sections 1910.331 through 1910.335.

OSHA will provide copies of this response to all OSHA field offices. Compliance Officers (CSHOs) will be instructed to use this response for reference when evaluating the safety of printing presses during workplace inspections.

Thank you for your patience and cooperation in this matter.


Patricia K. Clark, Director
[Directorate of Enforcement Programs]


Corrected 4/27/2004

The following is a general summation of the application of the OSHA standards, 29 CFR 1910.147, 1910.212, and 1910.219 for pressroom workers:

  • When maintaining or repairing equipment, always place the machine in SAFE condition and LOCK OUT the power to avoid the danger of serious injury to yourself and other workers.
  • Before maintaining or repairing any equipment, lock out the main electrical power disconnect, bleed off all hydraulic and pneumatic systems, secure all parts that can fall, and take any other specific precautions required for the particular equipment.
  • A warning tag or power box lock should be installed to prevent others from starting the equipment, before maintenance is completed and to alert them that maintenance or repair work is in progress. When not in use, turn the equipment OFF.

Thus, to be more explicit, it is consistent with the application of OSHA standards to printing presses that minor Servicing operations (such as clearing of certain types of paper jams; minor cleaning, lubricating, and adjusting operations; certain plate and blanket-changing tasks; and, in some cases, paper webbing and paper roll changing) can be accomplished using the inch-safe-service method, where the safety practices inherent under conditions of normal production operations will prevail.

However, when service and Maintenance operations are performed which lead to other workplace hazards, such as unexpected energization of machines or equipment or unexpected release of energy, the OSHA Lockout/Tagout requirements apply. Examples of such typical Servicing and maintenance activities requiring Lockout/Tagout Procedures are as follows:

  • Operations where auxiliary motors and pile motors are not disabled by the safe button and where the operator cannot maintain exclusive control of the machine or machine elements such as when cleaning frames and braces, cleaning the feeder, and delivery on sheet-fed presses, or when cleaning the reel stand and other parts of the infeed on web presses, or when cleaning or replacing air filters used to supply ventilation for toxic or flammable materials or heat generating electrical equipment.
  • Operations that require the machine operator to remove major parts of the equipment such as panels or other barriers that restrict access to moving mechanical parts or energized electrical equipment; or to perform extensive work without removal of such components; or to perform work requiring the operator to leave the immediate area containing the operating controls where exclusive control by the operator is required. Thus, for example, roller removal would require Lockout/Tagout when two people are required and/or there are no quick release sockets which would permit safe roller removal by one person.
1991, August 5 - Motor starter circuits and energy isolation devices.

Standard: 29 CFR 1910.147

Relevance: Discusses relationship of motor starter circuits and energy isolation devices (29 CFR 1910.399, 29 CFR 1910.305, 29 CFR 1910.147); definition of energy isolating device (b).

August 5, 1991

SUBJECT: Interpretation of "Energy Isolation Device" Application of 1910.147 to Conveyors

This is in response to your memorandum of February 12, requesting answers to three questions concerning the relationship of motor starter circuits and energy isolation devices as defined in the Lockout/Tagout Standard, 1910.147. Please accept our apologies for the delay in responding. Your questions and our answers are listed below.

Question 1: It is recognized that a motor starter is a control circuit device. Did the writers of these standards intend that assured control of the motor starter in the "off" condition be accepted as an energy isolation device?

Answer: The intent of the standard was not to include motor starter circuits within the scope of the definition of energy isolation devices.

For further clarification, the definitions of certain terms that have application to the 1910.147 (Lockout/Tagout) standard can be found in the complementary electrical OSHA standard, Subpart S of 1910. Three appropriate definitions are as follows:

  • 1910.399(a)(31) - Controller. A device or group of devices that serves to govern, in some predetermined manner, the electric power delivered to the apparatus to which it is connected.
  • 1910.399(a)(40) - Disconnecting Means. A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.
  • 1910.399(a)(124) - Isolating Switch. A switch intended for isolating an electric circuit from the source of power. It has no interrupting rating, and it is intended to be operated only after the circuit has been opened by some other means.

Question 2: It is our understanding that the electric motor, once it is stopped using the motor-controller "stop" button and is spun down to a full stop, cannot restart without being activated by the motor-controlled starter and its control circuit. It is further our belief that deactivation of the motor-starter device, using two independent keyed energy isolation devices properly wired and installed, can be effective in preventing the motor from starting and energization of its control circuit. Does the standard prohibit the use of this type of control circuit device as an energy isolation device for Lockout purposes?

Answer: The intent of the standard was not to accept motor-controlled stop buttons or motor-controlled starter circuits as energy isolation devices. Thus during the Servicing and/or Maintenance of equipment, such mechanisms will not be sufficient to provide the protection envisioned by the standard. On the other hand, for normal production operations, such as during routine, repetitive package clearing operations on conveyor belts, mechanisms that permit work to be performed by using alternative measures which provide effective protection would be acceptable. Further clarification on this issue is provided in OSHA Instruction [STD 01-05-019 (formerly STD 1-7.3)], Appendix C, Paragraphs A.1. through 4. Also, please see the note under Paragraph 1910.147(a)(2)(ii)(B) of the Lockout/Tagout Standard.

It has been claimed in one of the OSHA Region V Area Office letters (to ARA-Technical Support thru Michael G. Connors dated 12/10/90) that "...A diagram from the 1990 NEC Handbook, which tends to support the company's proposed application of control energy isolation, has been provided as Attachment B." We have not seen Attachment B. However, from our knowledge of the 1990 NEC Handbook, we are not familiar where this support is given. It might be that reference is being made to Article 430-111 of the NEC which states the conditions under which a switch or circuit breaker is permitted as both controller and disconnecting means. This requirement, taken from the 1990 NEC, is repeated here for convenience as follows:

  • 430-111. Switch or Circuit Breaker as Both Controller and Disconnecting Means. A switch or circuit breaker complying with Section 430-83 shall be permitted to serve as both controller and disconnecting means if it opens all ungrounded conductors to the motor, if it is protected by an overcurrent device (which shall be permitted to be the branch-circuit fuses) that opens all ungrounded conductors to the switch or circuit breaker, and if it is of one of the types specified in (a), (b), (c) below:
    • (a) Air-Break Switch. An air-break switch, operable directly by applying the hand to a lever or handle.
    • (b) Inverse Time Circuit Breaker. An inverse time circuit breaker operable directly by applying the hand to a lever or handle.
    • (c) Oil Switch. An oil switch used on a circuit whose rating does not exceed 600 volts or 100 amperes, or by special permission on a circuit exceeding this capacity where under expert supervision.
  • The oil switch or circuit breaker specified above shall be permitted to be both power and manually operable.
  • The overcurrent device protecting the controller shall be permitted to be part of the controller assembly or shall be permitted to be separate.
  • An autotransformer-type controller shall be provided with a separate disconnecting means.

If this is the NEC Article referenced by the Cincinnati Area Office as Attachment B, then it obviously can be seen that it is not applicable to the proposed UPS installation since neither the Air-Break Switch, the Inverse Time Circuit Breaker nor the Oil Switch, as specified in 430-111(a), (b) and (c), is used in the UPS design. It should be further noted that both the Air-Break Switch and the Circuit Breaker must be "operable directly by applying the hand to a lever or handle." And again the UPS method would not satisfy this requirement.

Question 3: It has been proposed, since the motor starter includes control circuit devices and is itself a control circuit device, that it would not be acceptable as an "Energy Isolation Device," per the 1910.147 standard. In the event of control circuit or motor starter failure it could cause the actual three- phase wires feeding power to the motor, coils, armature, and the motor starter circuit to become Energized. Do you agree?

Answer: We agree.

The OSHA standard, 1910.147 (Lockout/Tagout), clearly stipulates that in order not to be covered by the standard while performing minor Servicing activities during normal production operations, the work must be performed using alternative measures which provide effective protection (emphasis provided). To provide effective protection, the isolation from the source of power must be positive. A dependency on automatically controlled circuits to provide this isolation, even where all ungrounded conductors to the motor are opened, is not positive.

With the proposed UPS method of conveyor stoppage, one scenario may occur as follows:

An UPS package jams on the conveyor and other packages quickly begin to pile up. The attendant immediately actuates the stop button at one of the keyed lockout (field station) devices. The conveyor comes to a stop and the attendant climbs aboard the conveyor to free the jammed packages. Lacking the direct control of a manually operated switch or breaker to remove power by disconnecting all power conductors, motor stoppage becomes dependent on the proper functioning of the control circuits. In this case, we assume that the automatic control circuitry in the motor control center malfunctions such that only one phase of the three phase source to the motor is opened (not an uncommon occurrence especially where the over-current protection device opens the third phase (L3) without disturbing the motor starter circuit). Because of the additional load placed on the belt by the jammed packages, the motor, now only operating on two phases, has insufficient torque and stalls, and the belt stops. The attendant, believing that the conveyor has been safely stopped because the maintained stop button on the keyed lockout device was actuated, climbs upon the belt in order to free the jammed parcels. However, as the jam is removed, the resulting load on the conveyor motor is reduced and the belt starts again with sufficient start-up torque from the two remaining phases which have not been disconnected. The attendant becomes unbalanced by the moving conveyor, slips and falls, and is injured.

Other scenarios can also be postulated as a result of the lack of effective (positive) energy isolation.

Wiring Considerations. In accordance with 29 CFR 1910, Subpart S, Electrical Standards, the UPS conveyor motor control installation must comply with the 1910.305(j)(4) requirements. The following table estimates UPS Compliance based on the UPS submitted schematic diagram:

OSHA Standard

UPS Compliance


A disconnecting means shall be located in sight from the controller location. (Refer to 1910.305(j)(4)(i) for definition of "In sight from.")



If a motor and the driven machinery are not in sight from the controller location, the installation shall comply with one of the following conditions:

  1. The controller disconnecting means shall be capable of being locked in the open position.
  2. A manually operable switch that will disconnect the motor from its source of supply shall be placed in sight from the motor location.
  1. Unknown
  2. No


This disconnecting means shall plainly indicate whether it is in the open (off) or closed (on) position.



The disconnecting means shall be readily accessible. If more than one disconnect is provided for the same equipment, only one need be readily accessible.


Refer to UPS Compliance with 1910.305(j)(4)(ii)(a)

Corrected 10/6/2004

1991, April 10 - Work permits in Lockout/Tagout Standard requirements

Standard: 29 CFR 1910.147

Relevance: Documents energy control procedures 29 CFR 1910.147(c)(4).

April 10, 1991

Mr. Duane Barns
DOW Chemical U.S.A.
2020 DOW Center
Midland, Michigan 48674

Dear Mr. Barns:

This is in response to your letter of January 31, to Joe Bode of my staff, concerning the use of work permits for Compliance with aspects of the Lockout/Tagout Standard requirements.

As you are aware, 29 CFR 1910.147(c)(4)(i) requires that employers document the procedure by which the Hazardous Energy of equipment is Isolated during Servicing/Maintenance operations.

During the meetings on the Lockout/Tagout regulations, discussions were conducted concerning the use of a "generic" procedure for the various types of energy which would be encountered at a facility. The generic procedure would have to be included as a component of the company's Lockout/Tagout procedure and would additionally require that the company procedure clearly enunciate the further specific requirements for Servicing and Maintenance "work authorization permits". The company procedure would have to specify that the work permit identify the equipment to be serviced, the types and unique energy characteristics to be encountered, methods for safe work, and the process or procedures to be used to accomplish the task.

It was recognized during the earlier discussions that the comprehensive use of a work permit system would be more efficient and relevant to the tasks than would be a "cookbook" type procedure which might not fully account for a specific situation as it had occurred. It was recognized that at the time of Servicing and Maintenance the operations engineers and personnel are in the logical position to identify the tasks and the energy related hazards which would be encountered during maintenance operations and could best document a safe procedure for the tasks. The company procedure must, however, specify that the employees are required to perform their work in accordance with the terms and limitations of the work permit.

It should be noted that the effective use of a work permit system is compatible primarily with an industrial operation where sufficient engineering and administrative support is available. A company procedure which mandates that "generic" procedures are to be augmented with specific operational procedures as part of a required work permit system provides for Compliance with the standard.

Thank you for your interest in workplace safety.


Patricia K. Clark, Director
Directorate of Compliance Programs

Source: www.osha.gov

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