What Is It
As defined by the Occupational Safety and Health Administration (OSHA), an arc flash is a phenomenon where a flashover of electric current leaves its intended path and travels through the air from one conductor to another, or to ground. The results are often violent and when a human is in close proximity to the arc flash, serious injury and even death can occur. Causes of arc flash vary and include corrosion, condensation, dust, dropping tools, and faulty installation.
Within the United States, the National Fire Protection Agency (NFPA) Standard 70E, Handbook for Electrical Safety in the Workplace is the standard that drives the requirement for arc flash risk assessment, equipment labeling, and PPE application. However, NFPA 70E is a voluntary compliance standard and because it is not a government entity, it has no power to enforce compliance with any of its standards.
To learn more, check out this blog on what is really required and how you can become compliant.