An arc flash is an electrical explosion that can occur in 3 phase systems under certain conditions. Arc flashes, also called arc blasts, can be powerful, violent, and deadly. One explosion on May 26, 2003 was captured on a security camera and can be viewed at YouTube – Arc Flash Accident – live cam. One of the maintenance workers in this video, nicknamed “Tiny,” is almost 300 pounds – you can see that he was hurled 12 feet by the blast. He then discovers that he is on fire – he was wearing clothing with polyester – and frantically works to strip off the burning clothing. Tiny was lucky – he survived.
It was less than 30 years ago that we understood the physics of arc flashes. Interested readers can download the paper by retired DuPont engineer Ralph Lee, “The Other Electrical Hazard: Electric Arc Blast Burns.” This paper is the original published work documenting describing the physics, equations, the impact on human tissue and clothing, and recommended protective equipment.
Within the past few years, OSHA has mandated that all workplaces adopt safety practices to protect workers from these accidents. See Selection and use of work practices – 1910.333 for the specific OSHA regulations.