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NFPA 70E – Electrical Safety in the Workplace

hazard warningAccording to the American Burn Association, about 325 workplace fatalities occur each year due to electrical incidents, many of which resulted from “arc flash” events. Electrical violations were among the top 10 most frequent citations given out by the Occupational Safety and Health Administration (OSHA) in 2011. It is important to review NFPA 70E - Electrical Safety in the Workplace with employees to promote personnel safety and prevent unnecessary and expensive OSHA fines.

The NFPA 70E standard was developed to provide a practical and safe working area for employees relative to the hazards arising from the use of electricity. The hazards of electricity include direct and indirect shock, electrocution, burns, arc flash/blast, fire and explosions. The standard requires the use of electrical safe work practices on any system operating at 50 volts and above. The NFPA 70E standard is recognized as the industry standard to properly determine Hazard Risk Categories for equipment and identify the appropriate Personal Protective Equipment (PPE) to protect workers. This article will provide a brief explanation of an “arc flash” and highlight the primary benefits of an arc flash hazard analysis study.

What is an arc flash?

An arc flash is the result of a rapid release of energy due to an arcing fault between an energized part and another energized or grounded part. An arc flash occurs when the electrical current leaves its intended path and travels through air, resulting in an arcing fault. Because air has high impedance, this arcing fault will create heat. The heat will vaporize the copper or aluminum conductors or bus bar resulting in fire, blast pressure (up to 2,000 pounds per square foot), heat (to up 35,000 degrees Fahrenheit), sound (up to 140 decibels), and shrapnel. This combination of events that resulted from the high energy arc fault is known as an “arc flash.” Arc flash can be caused by catastrophic electrical equipment failures, but they are primarily induced by human error.

What is the purpose of an arc flash hazard analysis?

The primary purpose of the arc flash hazard analysis is to promote the safety of personnel that will be interacting with the electrical equipment. An arc flash hazard analysis determines the incident energy that is theoretically available at a designated working distance from energized parts, and therefore allows for the identification of the requirements for personal protective equipment (PPE) that qualified employees should wear when working on energized parts. The identified PPE is the minimal level of protection recommended to prevent serious injury in the event of an arc flash event.

Performing an arc flash hazard analysis can be very complex. Variables such as system voltage, available fault current, working distance, arc duration, protective device trip times, etc., can have significant impacts on the study’s results, and the subsequent determination of proper PPE. An arc flash hazard analysis should only be performed by a qualified professional.

Who should consider an arc flash hazard analysis?

Although arc faults are generally limited to systems operating in excess of 120 volts (as lower voltage limits normally will not sustain an arc), any facilities with voltages over 50 volts may need an overall electrical safety program that directs activity appropriate for the electrical hazards, voltage, energy level, and circuit conditions. Although OSHA does not specifically require the completion of an arc flash hazard analysis, the agency does require the use of appropriate PPE when working with electrical systems. An arc flash hazard analysis is the tool necessary to ensure compliance with OSHA standards, and more importantly, to protect the safety of personnel.

Although a critical component, an arc flash hazard analysis is just one aspect of a comprehensive electrical safety program. For more information about NFPA 70E Electrical Safety in the Workplace, contact Damon Chmela in the Eagan AE2S office, Damon.Chmela@ae2s.com; Jayme Klecker in the Maple Grove AE2S office, Jayme.Klecker@ae2s.com; Charles Haupert in the Maple Grove AE2S office, Charles.Haupert@ae2s.com or Adam Wahler in the AE2S Fargo office, Adam.Wahler@ae2s.com.





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