Arc Flash – Are You in Compliance?
Some utility personnel have resisted arc-flash compliance with the presumption that arc flashes and blasts are not a major issue for the utility industry. Organizations and standards committees such as IEEE (Institute of Electrical and Electronics Engineers), NFPA70E (National Fire Protection Association), EPRI (Electric Power Research Institute), CRN (Cooperative Research Network) and others confirm this as a false statement. An IEEE study concluded, “To decrease the number and severity of non-fatal electrical burn injuries, direct worker exposure to electrical arc energy must be reduced.”
Arc-flash and blast conditions occur in some utilities where operational personnel assert that the arc phenomenon “just happens as a way of doing business.” Utilities can no longer afford to disregard possible arc hazards or post arc events.
Proactive utilities evaluate electrical systems and equipment and develop processes to minimize and/or eliminate arc hazards before an incident occurs. Processes include, at a minimum, engineering controls, development of safe work practices and PPE (personal protective equipment).
Last line of defense
Although PPE does provide some level of personal protection, it should be the last line of defense for employee safety. Utility engineering staff should ensure existing equipment and new equipment has been evaluated to reduce arc-hazard exposures. Operational personnel should develop work procedures and processes to eliminate exposures that cannot be reduced. Reducing and eliminating arc exposures must be completed before developing a PPE compliance program.
Utilities without aggressive maintenance and system improvement programs may find themselves in positions with high levels of incident energy with extreme arc-rated clothing requirements. Employee resistance to wearing arc-rated clothing can be an issue when utilities focus only on PPE compliance without reducing and eliminating exposures.
Arc-hazard regulatory compliance is difficult since many standards are performance based and do not give clear, concise requirements. Current OSHA regulations, which have been the standard since the early ’90s, require employers to train employees who are exposed to arc hazards and to ensure clothing worn by employees does not increase the extent of the injury if an arc occurs. Does this mean employees must wear arc-rated clothing? If so, who is responsible for clothing payment? Does all clothing have to be arc rated?
Difficult answers
These are all good questions with very difficult compliance answers. OSHA acknowledges they could cite an employer for failure to provide necessary PPE for employee hazards and for general requirements if employees are not provided protection from electric arc and shock hazards. In order to enforce the requirements, OSHA acknowledges they will utilize industry practices, such as the NFPA 70E and NESC, to provide guidance about what types of protection are required and under what conditions protection should be provided.
Still, this does not give employers clear guidance to follow. Employers may not know exactly how OSHA will interpret the present law until a specific situation, such as a serious accident or fatality, requires the application of the law.
Future changes in OSHA standards will possibly outline better methodology for arc-hazard compliance. OSHA is presently urging standards development committees, such as IEEE, to continue researching arc hazards and developing new standards to address arc issues. IEEE and the NFPA have recently joined forces in an initiative to fund and support research and testing to increase the understanding of arc flash. The results of their collaborative project will provide information that will be used to improve electrical safety standards, predict the hazards associated with arching faults and accompanying arc blasts, and provide practical safeguards for employees in the workplace.
January 1, 2009 deadline
Arc-hazard compliance is a requirement of the NESC-2007. The NESC-2007 is a voluntary IEEE standard that many state agencies, typically public service commissions, have adopted as state law. NESC 2007 requires employers to perform an assessment to determine potential electric arc exposures. If the assessment determines employee exposures with incident energy levels greater than 2 cal/cm2, employees are required to wear clothing/clothing systems with an effective arc rating not less than the anticipated exposure. Utilities located in states where the code has been adopted will be required to complete the assessments by January 1, 2009 unless the state agency grants an extension.
The NESC does allow utilities to utilize tables 410-1 and 410-2 to determine the effective arc rating of clothing/clothing systems. Table 410-1 is based on open air phase to ground arcs and was not intended to address phase to phase or enclosed arcs. Although these tables are limited in their design, they can be a good option to get started. The intent of the tables was to provide a limited mechanism for small utilities to comply with the rules.
Some utilities are waiting to complete arc-hazard analysis because some current calculation methods have been challenged. EPRI, CRN and other member research networks have conducted or are in the process of conducting studies to help their members understand how to comply with the arc-flash provisions of the NESC.
Presently, NESC-2007 only requires arc-hazard assessments to be completed on voltages 1 kV or greater. This means that secondary systems are excluded if the utility can employ work rules and engineering controls to limit arc exposures. NESC-Subcommittee 8 has been addressing arc hazards for secondary systems for NESC-2012.
Major changes
The utility industry will possibly see major changes to the secondary exemption for arc-hazard assessments. Many utilities are changing work rules to require employees to de-energize a range of three phase pad-mounted equipment prior to performing secondary work. Serious arc-flash/blast conditions can occur when performing work on the secondary side of some pad-mounted equipment.
Many utilities have identified arc hazards through arc-hazard assessments and made a management commitment to address arc-flash/blast issues. There are still many questions to be answered concerning arc flash/blast.
Utilities cannot afford to wait and see what happens as issues addressed today in regulations and codes will be the foundation for future programs. Utilities should keep in mind programs, such as PPE, will change as arc knowledge increases. This process will be a long evolution of studies, theories and developed processes, which hopefully will result in a safer work place for all electric utility employees. iP
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