Our firm has had the experience of representing an individual who was injured in an Arc-Flash Explosion. In fact, he was burned over 97% of his body with 3rd degree burns…and lived! The event was quite horrifying in that it occurred in an electrical distribution center that was 6 feet wide by 25 feet long. It is not known for sure how the event occurred but it is speculated that a “tool” of some sort fell from above, lodging between two buss bars, causing the electrical arc to occur between the buss bars, resulting in the electrical arc igniting between the bars through the tool and connecting with the other buss bar. One of our experts surmised that temperatures during the “Arc-Flash” approached or exceeded 35,000 degrees Fahrenheit. The mere fact that my client survived was nothing short of a miracle.
Arc-Flash is the light and heat produced from an electric arc supplied with sufficient electrical energy to cause substantial damage, harm, fire or injury. Electrical arcs experience negative incremental resistance, which causes the electrical resistance to decrease as the temperature increases. Therefore, as the arc develops and gets hotter, the resistance drops, drawing more and more current (runaway) until some part of the system melts, trips or evaporates, providing enough distance to break the current and extinguish the arc. When an uncontrolled arc forms at high voltages, and especially where large supply wires or high-current conductors are used, arc-flashes can produce deafening noises, super-sonic concussive-forces, super heated shrapnel, temperatures far greater than the sun’s surface and intense, high energy radiation capable of vaporizing nearby materials. The result of the violent event can cause destruction of equipment involved, fire, and injury, not only to the electrical worker but also to bystanders. During the arc-flash, electrical energy vaporizes the metal, which changes from a solid state to gas vapor, expanding it with explosive force. For example, when cooper vaporizes it suddenly expands by a factor of 67,000 in volume. Destruction also arises from the intense radiant heat produced by the arc. The metal plasma arc produces tremendous amounts of light energy from far infrared to ultraviolet. Surfaces of nearby objects, including people, absorb this energy and are instantly heated to vaporizing temperatures.
Three key facts determine the intensity of an arc-flash on the surroundings. These factors are the quantity of fault current available in a system, the time until an arc-flash is cleared, and the distance an individual is from a fault arc. Various designs and equipment configuration choices can be made to effect these factors and in turn, reduce the arc-flash hazard. After making allowances for these factors, a design can be created to provide for a much safer environment. In our case, we were able to determine that defendants were provided with several solutions that would have prevented the arc-flash, however, management failed to see the safety default. Experts in this field were able to present several courses of conduct on the part of the company that would have prevented the accident. The company failed to perceive the hazard consequently with no adequate design to prevent the injury.
If you are the victim of an Arc-Flash, do not assume that nothing could have been done. There are many excellent safety electrical engineers and their expertise is necessary to properly analyze the event. And as always, time is critical. The sooner the event is investigated, the better.