Implementing Enclosure Solutions to Minimize Arc Flash Exposure

Industries continue to become more technology driven, with a heightened need for electronic components on the plant floor. Those working around energized equipment must be prepared for increased arc flash dangers.

• By Garrett Potvin
• May 01, 2012

In today's demanding industrial environments, electrical enclosures protect critical equipment and components from particle and moisture ingress. However, protecting equipment from failure due to foreign contaminants should not be the only consideration when selecting an electrical enclosure solution. The equipment housed within these enclosures is energized, which can pose a serious arc flash risk -- a potentially fatal hazard that occurs as a short circuit between electrified conductors, resulting in an explosive blast of flame, debris, sound, and heat that can reach 35,000 degrees Fahrenheit in less than one second. Currently, 80 percent of all electrical injuries are burns that result from an arc flash, with more than 2,000 employees suffering arc flash-related injuries each year, according to the National Fire Protection Association.

For operators working with or around energized equipment, they must understand the serious arc flash risks they are challenged with and must learn the safety solutions available to reduce the risk of arc flash injuries. To guide employers in selecting proper protective equipment, organizations such as OSHA and NFPA explain common risk factors and outline proper safety measures for arc flash hazards. Facility managers can improve the safety of their employees while accessing equipment and components housed within electrical enclosures when they have the proper equipment installed and follow the correct safety procedures.

Selecting electrical enclosures that can protect both workers and equipment simultaneously is a cost-effective and proactive safety measure against arc flash. Innovations in electrical enclosure technology provide solutions that not only prevent equipment contamination, minimize unnecessary exposure to arc flash conditions, and increase productivity, but also ultimately improve company profitability and efficiency.

Safety Standards
Before implementing any electrical enclosure safety solution, facility managers must be knowledgeable on the current standards regulating electrical hazards in the workplace.

OSHA was created to ensure the safety and health of workers by setting and enforcing standards. OSHA provides training, outreach, and education to encourage continual improvement in workplace safety and health. In accordance with its mission to be a comprehensive workplace safety resource, OSHA also created electrical safety guidelines. For instance, OSHA mandates that electrical work should only be administered on de-energized equipment to minimize the likelihood of igniting arc flash, and it requires that the appropriate lockout/tagout procedures be followed to ensure the equipment is not accidentally re-energized.

Further, OSHA states that access to potentially energized equipment capable of generating arc flash must be limited to qualified personnel with extensive protective clothing and equipment. A qualified person is one who has skills and knowledge related to the construction and operation of the electrical equipment and systems and has received safety training on the hazards involved.

NFPA 70E was originally developed to address electrical hazards in the workplace, and it contains detailed instructions on achieving electrical safety there. NFPA 70E also provides safety guidelines for employees who are working directly with equipment housed in enclosures. The standard states that electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are housed within other dwelling units and are likely to require examination, adjustment, servicing, or maintenance while energized must include a warning label. The label must clearly warn employees that an arc flash hazard exists and must indicate the risk level.

Additionally, NFPA 70E requires employers to provide protective equipment and clothing if an operator intends to open an electrical enclosure containing voltage greater than 50 volts alternating current (VAC). The standard provides detailed guidelines outlining the type and amount of protective clothing necessary. Flame-resistant clothing requirements are based on each application's calories per centimeter and ranges from flame-resistant pants, shirts, and coveralls to arc flash suits, with accessories such as boots, gloves, and masks also included. NFPA 70E provides a chart to guide facility managers through selecting the proper protective gear that corresponds with their risk level. Further, when working with electrical enclosures, it states that no arc flash hazards exist while the unit remains closed. While that is clearly the safer option, not all systems can accommodate that level of security without impacting productivity.

Implementing Equipment to Minimize Exposure
To meet the converging industry demands requiring increased safety and unimpeded productivity, enclosures now offer design features and accessories that provide reduced exposure to arc flash hazards. Enclosure safety systems are engineered to provide access to the enclosure components without requiring the operator to open the enclosure to obtain data. With options including windows, external data pockets, data interference ports, power isolation enclosures and additional accessories, these safety systems enhance employee protection while improving overall efficiency.

• Windows allow electrical enclosure operators to monitor components visually. They provide superior accessibility and safety. Models are available in rugged materials, such as stainless steel, for enhanced durability, and equipped with oil-resistant gaskets to provide a watertight seal around the perimeter of the frame. Windows are available in a range of sizes, accommodating enclosures in virtually any size in diverse applications.
• External data pockets are used to house important manuals, documents, worksheets, and printouts. They enable operators to access these resources without opening themselves up to risk of serious burns or more fatal consequences. Mounted on the outside of electrical enclosures, data pockets provide quick, easy, safe access to necessary data and records, ensuring constant availability and reduced arc flash exposure. External data pockets are engineered to maintain the integrity of the enclosure, while the cover and plate gasket ensures electrical enclosures uphold the Type 4/12 rating. To suit any existing or new enclosure solutions, external data pockets complement new designs or can be retrofitted for existing equipment.
• Data interface ports provide external plug-ins to equipment inside the electrical enclosure. Operators are often required to open the enclosure to obtain data, modify settings, or perform routine maintenance, increasing the likelihood of a possible arc flash ignition. Data interface ports allow users to interact with the equipment without requiring them to have direct contact. By implementing specifically designed panels that are wired to designated equipment inside the electrical enclosure, these ports ensure reliable yet safe access to equipment. By utilizing data interface ports, operators have an external pass-through port that allows them to monitor performance, change settings and extract data while the enclosure door remains closed. This ensures that while the devices are powered on, workers can manage programming parameters without needing to manually manipulate the equipment.
• Power isolation enclosures, or external disconnect enclosures, provide safe disconnect capabilities and overcome a significant challenge. Traditionally, disconnect switches were located inside the electrical enclosure, where live power is still being fed to the switch -- presenting serious arc flash risks when operators required access. As a smaller enclosure interlocked to the main enclosure, power isolation enclosures house only the disconnect switch or circuit breaker, removing it from within the enclosure. This enables them to sequester the disconnect switch or circuit breaker from the main control panel. External disconnect enclosures pass power from the disconnect enclosure to the main enclosure through a terminal block mounted on the shared enclosure wall. The live-line side is isolated in the external disconnect enclosure, and when the disconnect switch is off, there is no power being fed into the main control enclosure. By segregating the switch or circuit breaker, technicians are able to effectively work inside the main enclosure without requiring personal protective equipment. This minimizes exposure risk while still maintaining the highest level of productivity.
• Accessories such as folding shelves enhance enclosure safety systems. Folding shelves increase productivity by establishing an on-site workstation, enabling workers to set laptops or other equipment on the shelf to provide a workspace where they can view equipment and record data simultaneously.

Moving Forward
Industries continue to become more technology driven, with a heightened need for electronic components on the plant floor. Individuals working directly with or around energized equipment must be prepared for the increased prevalence of arc flash dangers. Facility managers can increase safety without impeding productivity by understanding the advancements in enclosure technology and the innovative safety features and accessories available to minimize arc flash hazards. Visit www.hoffmanonline.com for information.