A Flash, a fireball and a boom…


What is it?  Where does it come from?  What causes it to happen?  Is it dangerous?  What’s it called?

ARC FLASH – Some of you may have heard the term “Arc Flash”, but what is it?  Arc Flash is the result of a rapid release of energy due to an arcing fault between a phase bus bar and another phase bus bar, neutral or a ground. During an arc fault the air is the conductor.

OSHA (Occupational Safety and Health Administration) put into effect a regulation in 2014 that requires companies that have the electrical capacity to produce an arc flash, to provide their employees and contractors with information that explains the amount of incident energy (the arc) and the proper PPE (Personal Protection Equipment) to wear and the required boundaries (to keep employees safe from entering).

Facts about Arc Flash:

  • Electrical arcs produce some of the highest temperatures known to occur on earth, up to 35,000°F. This is 4 times the temperature of the surface of the sun which is about 9000°F.
  • Fatal burns can occur when the victim is several feet from the arc. Serious burns are common at a distance of 10 feet.  Staged tests have shown temperatures greater than 437°F on the neck and hands of a person standing close to an arc blast.
  • Arcs spray droplets of molten metal at a high speed. Molten metal from an arc can be propelled for distances up to 10 feet. Blast shrapnel can penetrate the body.
  • Blast pressure waves have thrown workers across rooms and knocked them off ladders. Pressure on the chest can be higher than 2000 lbs./sq. ft.

Thompson Specialty Services provides Arc Flash Risk Assessments for our existing clients and also for new clients.  To have a better understanding of what an arc flash is, please click on the link below and see the Thompson Specialty Services video on arc flash.