In theory, lockout/tagout (LOTO) is a simple concept. Basically, you disconnect equipment or circuits from their energy source and put a lock or tag in place, so no one can connect the equipment while you work. This should control any hazardous energy to which employees will be exposed. From here, it’s hard to determine whether the details of the operation make it a complex issue, or the guidance offered by regulations and consensus standards confuses matters. Lost in the details and regulations are procedures for dealing with energy sources other than electrical, such as mechanical, hydraulic, etc., and the operational factors, such number of crews involved and transfer of LOTO from one shift to another.
Regardless, one must take proper steps to control the hazardous energy. The best way to accomplish this is by following existing guidelines. The LOTO procedures found in NFPA 70E Standard for Electrical Safety in the Workplace are vital. NFPA 70E is the consensus standard most commonly referred to for electrical safety-related work practices. The Occupational Safety and Health Administration (OSHA) regulations dealing with LOTO also are important, but one’s ability to follow NFPA 70E guidelines should address OSHA compliance or at least provide a foundation for any other procedures offered for controlling hazardous energy.
NFPA 70E was conceived in 1979. It applies to all installations covered by the National Electrical Code (NEC). The committee that created the standard consisted of competent individuals representing all interests.
The NFPA 70E requirements for controlling hazardous energy are in Article 120 Establishing an Electrically Safe Work Condition. It is divided into three sections:
Section 120.1 Process of Achieving An Electrically Safe Work Condition: This section offers six basic criteria for ensuring an electrically safe work condition. 1.) Determine all possible sources of electrical supply, using up-to-date information and including drawings, diagrams and identification tags. 2.) Properly interrupt the load and open disconnecting devices. 3.) Verify that circuits are open visually if possible. 4.) Apply locks and/or tags. 5.) Test for the absence of voltage phase-to-phase and phase-to-ground. 6.) If there is the potential for induced or stored voltage, apply grounds rated for the available fault duty.
Section 120.2 Working On or Near De-energized Electrical Conductors or Circuit Parts That Have Lockout/Tagout Devices Applied: This section addresses the details of the LOTO procedure. It stipulates that all electrical circuits, conductors and parts must be considered energized until the LOTO procedure is complete. Any employees directly or indirectly exposed to the electrical energy must be involved in the process. Training must be provided in accordance with their involvement. A plan and procedures must be in place for execution of all elements of LOTO. This includes the training required, unique identification of the LOTO devices, the forms of control used, elements of control, coordination with LOTO procedures for other energy sources, and annual audit procedures.
LOTO devices must be clearly identified as that type of device and may not be used for another purpose. Locks must be associated with and operable by only the individual that installed it. Tags shall be suitable for the purpose and contain a statement prohibiting operation of the disconnecting device and removal of the tag.
The forms of control are related to the complexity of the energy control. A qualified person uses an individual LOTO when the disconnecting means remains visible to that person during the work, which does not extend beyond one shift. A simple LOTO is used when qualified people are working on one set of conductors or circuit parts. Each person must have control over his or her lockout. A complex LOTO is used when there are multiple elements involved, such as multiple crews, energy sources or locations. In a complex LOTO, a person is appointed responsibility for the procedure. He or she must account for all energy sources and all people working on the job. A written plan is necessary for execution of the LOTO.
In each procedure, the steps are very similar. Step 1 is to notify all personnel involved that a LOTO will be implemented and the reason for it. Step 2 is de-energize. Step 3 addresses the release of any stored energy. Step 4 is the application of the lockout and/or tagout devices. Step 5 is verification. An attempt to operate the equipment or circuits must be performed along with testing for the absence of voltage. It is critical that the operation of the voltage tester be verified before and after it is used to test the circuit or equipment. Step 6 is the application of grounds, as needed, to address the potential for induced voltage. Once completed, the circuit or equipment is considered locked out and in an electrically safe work condition. Work can now be performed.
Section 120.3 Temporary Protective Grounding Equipment: Grounds must be placed to prevent hazardous differences in electrical potential. They must be capable of conducting the maximum fault current and have impedance low enough to cause immediate operation of protective devices in the event of unintentional energizing of the conductors or parts. All grounds must meet the criteria established by the American Society for Testing and Materials (ASTM) F 855 Standard for the Specification of Temporary Protective Grounds to be Used on De-energized Electric Power Lines and Equipment.
Applicable OSHA standards
There are other types of energy besides electrical, which must be considered in LOTO. There also are a number of different operations in which these hazards can be presented. To ensure all hazardous energy is effectively controlled, OSHA has established a number of regulations governing the procedures of LOTO.
The General Industry Standard 1910.147 The Control of Hazardous Energy applies to the control of energy during servicing and/or maintenance of machines and equipment. This includes mechanical, pneumatic, electrical and any other energy sources. It does not cover construction activity, installations for the purpose of power generation, transmission and distribution, and electrical energy for “electric utilization installations.”
Construction LOTO for controlling electrical energy is addressed in 1926.417 Lockout and Tagging of Circuits. This standard offers a brief statement, requiring that circuits be de-energized, made inoperative and have tags attached. LOTO rules for power transmission and distribution can be found in 1910.269 Electric Power Generation, Transmission, and Distribution for General Industry and Subpart V Power Transmission and Distribution 1926.950 General Requirements for Construction. Other electrical installations are governed by the general industry standards in Subpart S Electrical. LOTO from this Subpart is specifically addressed in 1910.333 Selection and Use of Work Practices.
Each of these standards has basic requirements in common. In fact, OSHA finds an electrical LOTO program using the procedures in 1910.147 compliant with 1910.333 so long as the procedures include the following:
1. A qualified person ensures tests are performed to verify the circuit is de-energized and will not be re-energized by induced voltage or backfeed.
2. If a tag alone is used, an additional safety measure must be present that includes the removal of an isolating circuit element, blocking of a controlling switch or opening of an extra disconnecting device.
Although the regulations have similarities, compliance often mandates that one navigate these standards to address requirements applicable to the unique steps for tasks in given operation. For example, in power transmission and distribution, OSHA authorizes the system operator to place and remove LOTO devices that are in a central location and inaccessible to the authorized employees. However, the employer’s hazardous energy control procedures must still provide employees the same level of personal control they would have in personal LOTO.
Electrically safe work condition
In the example cited above, the employer must decide how to meet the level of protection required. This is common in OSHA standards. They are written in performance-based language, leaving the employer to determine procedures. When a compliance inspection is conducted, OSHA may defer to consensus standards to compare the effectiveness of the employers’ procedures with industry-accepted practice.
This brings us back to the problem of deciphering LOTO. As discussed, NFPA 70E provides the best guide for electrical contractors. It applies to all NEC installations. It calls for live parts to be placed in an “electrically safe work condition” before employees can work on or near them. The standard defines such a work condition as a “state in which the conductor or circuit part to be worked on or near has been disconnected from the energized parts, locked/tagged in accordance with established standards, tested to ensure the absence of voltage and grounded if determined necessary.”
To help contractors achieve compliance and better manage their LOTO operations, the National Electrical Contractors Association offers a manual entitled Guide to NFPA 70E Lockout/Tagout (LOTO). It is available as a field manual with graphic step-by-step instructions. An interactive software version for supervisors and owners provides the same instructions with additional links to the references on which the instructions are based. The software also contains templates for implementing a LOTO program, including a LOTO device checklist, complex LOTO written plan, LOTO audit form and more.
All electrical contractors should become familiar with NFPA 70E and the applicable OSHA regulations to ensure the safety of their employees.
O’CONNOR is with Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. Based in Waverly, Pa., he can be reached at 607.624.7159 or firstname.lastname@example.org.