What is Arc Flash?

BY: Christina Hansen


arc-flash protectionWhat is Arc Flash?
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 actually 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, and cause damage to the eardrums, lungs, 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 that are 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 isn't able to return to what it was before the arc blast incident.


How do Arc Flash incidents affect businesses?
In addition to financial and legal consequences like steep OSHA fines, personal injury lawsuits, costly repairs and temporary facility shutdowns, arc flash incidents can also rob companies of employees on a temporary or permanent basis, depending upon whether or not victims survive, and can (or wish to) return to work post-recovery. The morale of other employees also suffers greatly, as it can be extremely traumatic for individuals to witness an arc flash incident resulting in the injury or death of a coworker.


How can Arc Flash injuries be prevented?
There are several steps that employers can take to reduce the risk of arc flash/arc blast injury to employees.

  • Training. Ensure that employees are thoroughly trained in safe work practices and procedures, in accordance with OSHA guidelines and NFPA 70E (Electrical Safety Requirements for Employee Workplaces).

  • Proper Signage and Labeling. One of the most important elements in battling arc flash is letting employees know exactly where risks exist. Warning labels and signage on power panels, high-voltage machinery and power lines are extremely important, and can help to ensure that employees take the proper preventive measures before beginning working on or near potentially dangerous components.

  • De-Energizing. Whenever possible, de-energize high-voltage equipment before beginning maintenance and repair work.

  • Personal Protective Equipment. Equip employees with a level of Personal Protective Equipment (PPE) that is appropriate to the tasks they perform. This can include, but isn’t limited to, flame retardant over-clothing, arc flash hoods, face shields, arc flash gloves, and arc suppression blankets.