An "arc flash" is an electrical short circuit that originates from an exposed live conductor and then travels through the air until it reaches another conductor or the ground. Arc flash happens when there is a breakdown of electrical resistance (or impedance) in the air surrounding a conductor. If there’s enough voltage present in the conductor while air resistance is low, the voltage can make its own low-impedance path that arcs through the air and straight to the ground — or to another conductor nearby.
ARE ARC FLASH AND ARC BLAST THE SAME THING?
It's easy to use the terms interchangeably, but arc flash and arc blast are two different things. You can think of them as the cause (arc flash) and effect (arc blast). When a short circuit (or arc flash) occurs, it can often cause arc blast, a type of highly dangerous electrical explosion.
WHAT DOES ARC BLAST DO?
There are plenty of possibilities with arc blast and none of them are good. To begin with, it gives no warning, so there's no time escape. Pressure waves generated by an arc flash explosion can carry a force up to thousands of pounds per square inch, which is powerful enough to knock down or throw nearby workers, causing damage to the eardrums, lungs, the brain and other organs. Other effects of arc blast include:
- • Searingly high temperatures. The heat and flames generated by an arc blast can reach temperatures of up to 20,000° Kelvin, or 35,000°F. This is enough to vaporize metal components, as well as cause life-threatening (or even deadly) burns to personnel in the immediate vicinity.
- • Shrapnel from exploded equipment. The explosive force of an arc blast can turn metal objects into high-speed shrapnel, which threaten to seriously injure or kill workers in the general area of the explosion.
- • Damage to eyesight. Arc blasts often create high-intensity light flashes capable of causing both temporary and long-term vision problems in personnel whose eyes aren't properly protected.
IS IT POSSIBLE TO RECOVER FROM AN ARC FLASH OR ARC BLAST INCIDENT?
While it's entirely possible for a person to recover from the effects of an arc flash or arc blast, it's likely that the process will be a long one. It's not unusual for arc blast burn victims to require months — and even years — of ongoing medical treatment (including skin-graft surgeries). Arc blast victims face extended work absences during the recovery process; and are sometimes unable to return to work altogether. In many cases, quality of life does not return to what it was before the arc blast incident.