An electric arc flash is a high-amp current that jumps through the air. It occurs when the path of the electric current is interrupted; the current then flows through the air to a new conductor or to ground, causing an explosion.
When arc flash occurs, there’s a brilliant flash of light followed by a burst of super-heated gas and droplets of molten metal explode outward from the equipment. There can be one or more explosions within milliseconds which generate extremely high temperatures.
Arc blast usually accompanies arc flash. It’s a tremendous shock wave of pressure. The blast can knock a person to the ground and disintegrate everything within a specific area, cause eardrums to rupture, and propel shrapnel with a force equal to a small hand grenade.
An arc flash/blast event can begin and end in less than a second; bystanders usually see a flash then hear a loud boom. When recorded by a camera, the footage reveals the massive amount of damage that occurs.