The National Fire Protection Association (NFPA) was first appointed a technical committee on Electrical Safety Requirements for Employee Workplaces in 1976.
This committee was tasked with assisting the Occupational Safety and Health Administration (OSHA) in preparing electrical safety standards that could be promulgated through the Occupational Safety and Health Act, enacted by Congress in 1970. The first edition of NFPA 70E, Standard for Electrical Safety Requirements for Employee Workplaces, was issued in 1979, and it has been regularly revised and updated in the years since.
NFPA 70E was the first nationally recognized standard for electrical safety-related work practices in the United States, and it served as the reference document for OSHA in its Electrical Safety-Related Work Practices regulation, promulgated in 1990. The electrical safety-related work requirements outlined in NFPA 70E provide crucial guidance for employers in complying with OSHA standards in the area of electrical safety and for employers as well as employees in identifying essential electrical safetyrelated work practices. For assistance in determining the appropriate safeguards and required levels of personal protective equipment (PPE) for different tasks on energized equipment, the 2015 edition of NFPA 70E now includes an arc flash hazard identification and PPE requirement table. For various tasks and equipment conditions, this table identifies when arc flash PPE is or is not required. If arc flash PPE is required, additional tables identify various arc flash PPE categories (e.g. 1 through 4) based on the type of equipment and electrical ratings involved. Another table then specifies the required level and type of PPE to be used, such as the minimum arc rating for clothing, for the specific PPE category involved. In general, the judgments regarding risk reduction that inform the tables are based upon the collective experiences of members of the NFPA 70E Technical Committee. However, the 70E Committee is always interested in increasing its knowledge base of experience by drawing upon new empirical incident data or better delineation of the actual hazards associated with adverse electrical events.
Another area of recent technical committee discussion has been promoting recognition of the need for greater protection of non-electrical workers who may be exposed to electrical hazards while performing their non-electrical job functions. Historically, the scope of NFPA 70E has been more focused on the needs of qualified electrical workers who routinely work on energized electrical conductors and circuit parts during the course of their work. Because workers in non-electrical jobs may not have extensive electrical safety training and their work may not be guided by electrical safety work practices, the NFPA 70E technical committee added the following informational note to the Scope statement of the 2015 edition of NFPA 70E: This standard addresses safety of workers whose job responsibilities entail interaction with electrical equipment and systems with potential exposure to energized electrical equipment and circuit parts. Concepts in this standard are often adapted to other workers whose exposure to electrical hazards is vii unintentional or not recognized as part of their job responsibilities. The highest risk for injury from electrical hazards for other workers involve unintentional contact with overhead power lines and electric shock from machines, tools, and appliances. (National Fire Protection Association, 2014) Better information on the electrical hazard injuries to non-electrical workers is needed to assess the guidance needed in NFPA 70E to these workers in future editions of the standard. To this end, this special project, “Review of Occupational Injuries from Electrical Shock and Arc Flash Accidents,” was requested by the NFPA 70E Technical Committee in order to generate a more rigorous foundation for assessing risk in relation to electrical hazards, including quantitative data on electrical injuries, in-depth assessment of select adverse electrical events, and a review of literature on electrical hazards. Such information is essential for assessing the effectiveness of current safety practices, potential barriers to implementation, and prospective areas for future safety initiatives. Through the sponsorship of the Fire Protection Research Foundation, the project was able to move forward, and this report presents the findings of the research. Some clarification about terminology may be useful in introducing this review of electrical injuries to workers.
It is not uncommon in discussions of workplace electrical hazards to see reference to “electrical workers: and “non-electrical workers” in order to distinguish between workers who routinely work with energized conductors or other circuit parts and those who do not. In fact, those who work with electrical energy sources can be found in a range of occupational groups, as elaborated in the Standard Occupational Classification (SOC) System used by U.S. federal government agencies. For instance, the SOC places electricians and electrician helpers under “Construction and Extraction Occupations,” while line (power -line and telecommunications) installers and repairers and electrical and electronic equipment mechanics, installers, and repairers are found under “Installation, Maintenance, and Repair Occupations,” and electrical and electronics engineers and technicians are found under “Architecture and Engineering Occupations.” Accordingly, the “electrical worker” distinction is, in some respects, more a reference to the type of work activity performed than to occupation. NFPA 70E does not itself refer to electrical workers, but instead refers to a “qualified person” as someone who has demonstrated skills and knowledge related to the construction and operation of electrical equipment and installations and has received safety training to identify and avoid any accompanying hazards. Background NFPA 70E is a national consensus safety standard that identifies safe work practices to protect workers from the hazards of electricity, including electric shock and electrocution, arc flash, and arc blast. NFPA 70E states “This standard addresses safety of workers whose job responsibilities entail interaction with electrical equipment and systems with potential exposure to energized electrical equipment and circuit parts. Concepts in this standard are often adapted to other workers whose exposure to viii electrical hazards is unintentional or not recognized as part of their job responsibilities. The highest risk for injury from electrical hazards for other workers involve unintentional contact with overhead power lines and electric shock from machines, tools, and appliances.”(National Fire Protection Association, 2014) In addition, the standard identifies safety procedures for other activities that may entail exposure to electrical hazards, such as installing conductors or equipment that connect to the supply of electricity.
The focus of NFPA 70E is on the hazards associated with electrical wiring and components within a building or related structure. Electrical safety practices in relation to work performed by electric utilities on the equipment and installations under their exclusive control fall outside the scope of NFPA 70E, but the standard does apply to installations used by an electric utility (such as office buildings, machine shops, etc.) that are not an integral part of a generating plant, substation, or control center. NFPA 70E identifies and elaborates upon essential components of workplace electrical safety work practices through its requirements around electrical safety training, the use and selection of personal protective equipment, electrical safety practices and procedures, equipment maintenance, and electrical hazard warning labeling. Requirements around safety training apply not only to employees who perform work on electrical equipment, but also those who work in the area of equipment that is energized. NFPA 70E establishes strict training requirements for qualified persons who are authorized to work on energized equipment. Other workers who may also be exposed to an electrical hazard must be trained in the safety-related work practices necessary for their safety. Employees who are subject to training requirements must undergo retraining at least every three years, and safety training programs must also be audited at least every three years to ensure compliance with requirements of the standard. When work has to be performed on electrical equipment, the preferred protection for employees set forth by NFPA 70E is to deenergize the equipment through a prescribed set of steps necessary to create an electrically safe work condition. NFPA 70E calls for normally energized conductors and circuit parts to be put in this electrically safe work condition if employees are within a limited approach boundary or arc flash boundary or if an employee interacts with equipment where energized conductors or circuit parts are not exposed, but there is an increased likelihood of injury from exposure to arc flash.
Only a qualified person can establish an electrically safe work procedure, and the first step in this process entails identifying all possible sources of electrical supply, if necessary by consulting plans, diagrams, or other documentation. For equipment to be considered electrically safe, all electrical conductors or parts to which employees might be exposed must be disconnected from energized parts and be locked and tagged out. Additional procedures to complete the process require the testing of all conductors and circuit parts to which employees may be exposed with a test instrument in order to confirm that they are not energized, and any equipment with induced voltages or stored electrical energy must be grounded. ix Except for certain tasks, such as testing and troubleshooting, when live parts or equipment are not made electrically safe for work as defined by NFPA 70E, a written energized work permit is required before work can proceed if the work takes place within a restricted approach boundary or the employee interacts with the equipment when conductors or circuit parts are not exposed, but there is an increased likelihood of injury from exposure to arc flash. The work permit must include: a description of the circuit and equipment that will be energized, a justification for work to take place in an energized condition, a description of safe work practices to address the additional hazard, the results of shock and arc flash risk assessments, designation of the voltage to which employees will be exposed, designation of the respective shock and flash protection boundaries, identification of the personal protective equipment that will be used to perform the work (based on the task and voltage/equipment, as specified by the standard), delineation of the methods for restricting access of unqualified persons into the work area, and evidence of a job briefing. The permit must be approved and signed by a responsible party who concurs with its contents and that deenergization is not feasible.
The shock and flash protection boundaries established by NFPA 70E specify the permissible distances that must be maintained between employees and energized electrical conductors or parts in order to enhance safety, and there are increasingly stringent requirements as the distance decreases. Only qualified persons or unqualified persons who are advised and escorted by a qualified person may enter a “limited boundary” approach, while a “restricted boundary” approach specifies the area which can only be entered by a qualified person with the proper level of personal protective equipment and appropriate tools. Approach boundaries are determined by the voltage of the energized object in the case of shock protection and by incident energy exposure level for flash protection. The standard spells out requirements for the level and type of personal protective equipment to be worn to protect against shock and arc flash within these boundaries, based on a determination of the hazard. There is a broad recognition that the electrical safety work practice requirements established by NFPA 70E have played a vital role in improving workplace safety for both electrical workers and non-electrical workers alike. However, although the incidence of fatal and non-fatal electrical injuries has decreased over the past 20 years, questions remain about how closely employers and employees follow NFPA 70E procedures in their everyday work practices and whether there are areas where NFPA 70E could provide additional improvement, either in its safety requirements or target populations.