Why are Arcing Faults Dangerous?

The energy that results from an arcing fault manifests as an arc flash, an arc blast or a combination of the two.


Arc flash is exposure to the tremendous thermal energy released by an arc fault, which results in a variety of serious injuries and in some cases death.

The temperature at the center of an arc fault can reach nearly 35,000 °F. At these temperatures, typical conductors, like copper, are converted from a solid, to molten metal, to a vapor in less than a thousandth (<1/10000) of a second. As a comparison, the surface of the sun is about 9,940 ºF.

As a result, the vapor can expand to nearly 67,000 times the volume of the solid, superheating the surrounding air almost immediately. The expansion of this vapor, along with the rapid vaporization of conductors, results in an explosion of concussive forces. Additional injury may occur from falls if the person affected is working at elevation, on a platform, walkway or ladder.

If unprotected, this heat is capable of producing incurable third degree burns instantaneously. Electrical burns are typically slow to heal and frequently result in amputation.

In addition, this heat can ignite clothing at distances of ten feet or more, presenting an additional hazard as a result workers have been injured even though they were ten feet or more away from the arc center.


Arc blast is exposure to the pressure blast released by an arc fault. This blast can also cause shrapnel to be hurled at high velocity, which can cause serious injuries or death.


Between all of this, an arcing fault has the potential to damage a person's sight, hearing, lungs, skeletal system, respiratory system, muscular system and nervous system in addition to burn injuries.

  • What do you see
    • Very bright flash of light
  • What do you hear
    • Loud arcing or boom
  • What do you smell
    • Heavy ozone odor

View Video 1 to see an actual arc flash/blast demonstration from Westex® by Milliken®.

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Video 1: Electrical Arc Flash Demonstration

Courtesy of Westex® by Milliken®



Figure 1: The Sun's Surface Temperature is About 10,000 Degrees Fahrenheit

Credit: NASA/SDO