NFPA 70 (National Electrical Code) requires electrical equipment that may be serviced while energized to be labeled with potential arc flash hazards. Methods for performing and calculating arc flash hazard are defined in NFPA 70E - Standard for Electrical Safety in the Workplace and IEEE 1584 - Guide for Performing Arc-Flash Hazard Calculations. OSHA requires employers to perform workplace hazard assessments and provide appropriate PPE along with training on how to properly use it. The OSHA requirements generally apply to entities that own and service their own electrical equipment. Equipment owners are responsible for having a study completed and labeling equipment.
Arc flash hazard studies should be performed by experienced and qualified electrical engineers knowledgeable in power system engineering, IEEE 1584, NFPA 70E, short circuit, device coordination and arc flash studies.
NFPA 70E states that arc flash hazard calculations need to be reviewed every five years or whenever there is a significant change in the electrical system.
Bonus Content: What is an Arc Flash?
An arc flash is an electrical explosion resulting from a release of energy that travels through the air between one conductor to another, or to ground. The results are often violent and potentially dangerous to personnel nearby. An arc flash may produce extreme temperatures, intense light, sound waves, and in extreme circumstances, an arc blast. Personnel who experience an arc flash may suffer from burns, blindness, hearing loss, other bodily injuries and possibly death. An arc flash can be the result of several conditions, but some of the more common causes include:
Accidental contact with equipment
Worn or gaps in conductor insulation
Damaged equipment or equipment that is underrated for the available short circuit current
Dust, corrosion or other impurities on the surface of the conductor
Bonus Content: How is an Arc Flash prevented?
While it is impossible to completely prevent an arc flash, there are several ways to mitigate the risk. One way is to de-energize electrical equipment prior to performing work on it. This removes the arc flash risk while the equipment is in service and should always be the first choice of action. Another way is to perform an arc flash study on the system to determine the level of risk associated at each piece of equipment and identify the proper PPE needed to protect personnel in the case of an arc flash. Protective device coordination in conjunction with an arc flash study can identify additional steps to adjust upstream equipment and modify electrical systems to lower the risk at pieces of equipment.
Questions about Arc Flash Studies? Contact Nate Boland (319) 325-6171
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