The Dangers of Arc Flash to Unqualified Personnel
Training and culture change are the solutions.
Training and culture change are the solutions.
By Ed McConnell
Allowing unqualified plant personnel to stand or work near exposed energized electrical conductors is an accident waiting to happen. Every year some 2,000 workers are admitted to burn centers because of arc flash injuries. While injuries to qualified personnel have decreased since 2005, many unqualified people are still suffering severe injuries or death. Some improved safety is because of better electrical system and equipment design, but much is because of increased personal protective equipment (PPE) use and making safe, informed decisions.
The arc flash/arc blast is the uncontrolled release of energy produced when a short circuit electrical current occurs in electrical systems. This flash includes extreme heat, molten metals, shrapnel, bright light, loud sound and percussive force. During arc flash, components fail and become heated to some 35,000F, then vaporize and expand. An arc blast is the ejection of the failed component's molten metal. Arc blast splatters this material on surrounding equipment and personnel. Equipment can be damaged, and people can be injured or killed by contact with the molten material and the accompanying effects.
Arc flash has been a recognized hazard in electrical systems long before safety measures were implemented for personnel protection. In 2000, National Fire Protection Association (NFPA) 70E made a move in identifying personal protective equipment (PPE) for individual work tasks. In 2002, the National Electric Code (NEC) included a statement requiring warning labels to be applied to all equipment at risk for arc flash: "Equipment that is likely to require examination, adjustment, servicing or maintenance while energized shall be field marked to warn qualified persons of potential electric arc flash hazards." The risk of arc flash has been further evaluated since 2000 and NFPA 70E has evolved with three more editions. This has led to new information being added to equipment labeling and refined PPE requirements. In 2009, the NFPA 70E gave significantly more direction, addressing conditions where personnel may need to work on energized electrical equipment and providing guidelines for selecting appropriate PPE components to reduce or prevent injury from arc flash. The latest 2012 version has further refined this information.
NFPA 70E defines a qualified person as "one who has skills and knowledge related to the construction and operation of the electrical equipment and installations, and has received safety training to recognize and avoid the hazards involved." An unqualified person is not skilled in these areas.
Despite the increased protection of electrically qualified personnel, a serious risk remains for unqualified employees who work nearby. Arc flash training is crucial. To avoid possible safety violations and fines, potential litigation, lost workdays and even employee death, company owners should offer thorough, up-to-date training even to employees who aren't consistently working around exposed energized electrical parts. To be effective, the training must focus on real-life examples, materials and labeling, and should be supported by a culture change that affirms an ongoing commitment to reducing arc flash injury.
Training: Personalization and Communication
Eliminating the risk of arc flash injury means greater productivity, and only training that leads to making the right decisions can eliminate this risk. By increasing arc flash safety, the company's overall success can be strengthened. Guided by a knowledgeable consultant experienced in arc flash evaluation and regulations, an owner can choose among various training techniques. A personal approach to the danger of arc flash is the most convincing way to reach personnel.
Using videos of real-life arc flash accidents, trainers can itemize the risk factors to watch for. One video shows how long it takes from the blast until a worker removes his burning clothes and walks away. In this same video, two workers are standing at the door of the electrical equipment while a third worker maintains the equipment. When a blast occurs, the video shows how the two onlookers are affected along with the one maintaining the equipment. The example demonstrates the responsibility of the qualified worker toward the personnel adjacent to the work area. In addition, there is a risk posed by observers who might inadvertently cause an accident.
Training should also expand the worker's awareness of associated risks such as any materials that are susceptible to arc flashes, whether they are worn by workers or present in the area. A polyester shirt is like a plastic bag that can painfully melt into the skin in the heat of an arc flash. Metal chains, watchbands and rings can become branding irons when exposed to that heat. Materials within range of a potential arc must also be assessed. Copper elements are highly expandable in high temperatures. More than the heat of an arc flash, the resulting projectiles can be lethal. The plasticized material surrounding a molded case circuit breaker might not melt, but it can fall apart and be hurled as shrapnel. Although protective clothing may be fire resistant, it is not body armor. The shrapnel-like plastic will still penetrate the fabric and skin. Heat from the blast also can ignite flammable materials within the arc flash boundary, so it's mandatory that the area be free of greasy rags, rolls of paper and other items that might catch fire.
Training should ensure trainees understand the arc flash information being provided for them. A factor in this communication is the arc flash labels on electrical equipment in their environment. These labels identify the level of the arc flash, the system voltage at this point and, new to the 2012 NFPA 70E, the arc flash boundary. From this communicated information, the qualified and unqualified personnel must be able to discern that they have to take special protection measures and know where to go to determine what they must do to protect themselves.
Trainees must be assured they are learning the most current requirements. The standards have changed through the years and will continue to change. The owner should establish methods to assure they stay abreast of changing standards. Failure to follow current standards can result in injury claims and litigation.
Positive Reinforcement for Culture Change
In addition to conducting arc flash safety training, facility owners need to build a culture that constantly stresses electrical safety and keeps their supervisors and their future replacements up to date on changing regulations. Culture change is more effective when positive reinforcement is used to build the employee's awareness of the arc flash hazard. A strong safety culture can only be established with well-trained supervisors and managers.
Culture change takes time and diligence. An organization will demonstrate it is embracing the necessary changes if it:
• Keeps up to date on changing regulations and their cycles;
• Holds safety meetings before starting an equipment task, which evaluates the task and creates a safe work plan;
• Encourages ongoing, additional training;
• Positively reinforces as demonstrated by supervisors;
• Evaluates on a system basis that proper PPE equipment is provided; and
• Works with all employees to individually assure the PPE is in proper condition.
Just as seat belts and airbags provide protection that might never be needed, putting an arc flash safety training program in place prepares employees and helps build a culture that may never be tested by an arc flash event. Fortunately, injuries of qualified personnel are declining. To ensure this decline continues, however, a fuller awareness of arc flash safety must be extended through training of unqualified personnel. Employees who know their supervisors have their safety at the top of their agendas will respond with higher productivity and a higher commitment to their organization.
About the author: Ed McConnell, PE, is a master engineer at SSOE Group, a global engineering, procurement and construction management firm. With 35 years of experience, McConnell specializes in facility electrical power distribution, large motor starting, lighting, electrical systems grounding, building grounding, building utilities electrical power and control, substations, security systems, communication systems, and fire detection and alarm systems. His experience includes electrical power system design in hazardous areas such as Class I and Class II environments. He can be reached at Ed.McConnell@ssoe.com.