The Formation and Hazards of Arc Flash

 The cause of Arc Flash can be attributed to accidental contact, protective devices with insufficient short-circuit current ratings, contaminated insulating surfaces, deteriorated or corroded equipment or parts, and other reasons.

Arc Flash is a phenomenon that occurs when a large amount of lethal energy is discharged due to a short-circuit of an exposed conductor, causing the air to ionize. During the period of air ionization, a large amount of arc fault current generates tremendous heat, with temperatures that can reach up to 35,000 degrees Fahrenheit, higher than the temperature on the surface of the sun. This can cause serious burns on human skin and even ignite clothing. It can also liquefy or vaporize nearby metal objects, such as copper, aluminum wires or iron components. At this time, the volume of metal rapidly expands due to its change in state from solid to vapor, causing explosive pressure and sound waves. The strong sound wave impact may cause deafness, and the accompanying bright light can cause temporary or permanent blindness. Solid metal fragments and other loose items such as tools may become lethal flying projectiles, causing serious harm to human beings. The phenomena that may occur during Arc Flash are shown in Figure 1.

Figure 1 The phenomena during Arc Flash