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What is Arc Flash?

The National Fire Protection Association (NFPA) describes an Arc Flash as “a dangerous condition associated with the release of energy caused by an electric arc.”

An Arc Flash is a phase-to-phase or phase to ground electrical fault, and the energy produced melts components, flooding the air with conductive particles. The temperature of an Arc Flash can reach up to 35,000 degrees F.

Copper expands to 67,000 times its original volume when vaporized. The flash occurs instantaneously, releasing a huge amount of energy in a very short period of time.

3rd degree burns form when skin is exposed to 200º F for less than 1/8th of a second.

Three main causes of an Arc Flash:

  • Mechanical

  • Environmental

  • Human Error

An arc flash is caused by a reduction of the insulation or isolation distance between energized components. This could be caused by a tool being inserted or dropped into a breaker or service area, or other elements that may be accidentally left behind that could compromise the distance between energized components. Often, incidents occur when a worker mistakenly fails to ensure that the equipment has been properly de-energized.

The most common cause of Arc Flash accidents is Human Error.

Arc flash incidents typically occur in applications above 120V and can occur when electrical equipment is being serviced or inspected. An arc flash can cause serious equipment damage and render the equipment no longer usable, causing a disruption of a facility’s operation for hours or days, depending on the equipment, its age and how quickly service can be restored. The explosion also can completely destroy the equipment, leaving it unsuitable for service.

Arc Flash causes over 2,000 severe injuries every year to workers, and can kill at distances of 10 ft. The cost of treatment can exceed $1,000,000/case does not include litigation fees or process loss, and treatment can require years of rehabilitation. The victim may never return to work or retain quality of life.

In some industries it is possible to protect the worker from the arc flash but the arc blast will kill you.


  • An arc blast is a high pressure wave.
  • Copper expands 67,000 times as it vaporizes.
  • Sound pressure > 160 dB
  • Debris accelerated to 700 mph
  • People can be killed with no external sign of injury. A blast can breaks bones, and rupture ear drums.

More than sufficient time should be spent designing and evaluating high amperage circuit breakers and other products to limit the arc flash incident energy and provide the highest protection to workers exposed to arc flash hazards.

Additionally, companies should provide proper Arc Flash electrical safety training and personal protective equipment (PPE), preventative maintenance services, and other options that can help companies reduce the threat from electrical or arc flash incidents within their facilities.

The things we expect to happen don’t cause injuries. It’s always the things we don’t expect or anticipate happening that injure people and cause fatalities.”

OSHA Mandate:    The Law

The Occupational Safety and Health Administration, OSHA, has some minimum requirements that are invoked whenever employees are going to perform installation, maintenance, or repair on equipment.

There are three major sections that apply when this occurs:

  • CFR 1910.147, which applies for General Industry applications
  • CFR 1926.147, applicable to Construction
  • CFR 1910.133 Subpart S, which directly involves electrical hazards

NFPA 70E:    Industry Best Practice

The NFPA 70E standard is produced by the National Fire Protection Association, they are one of the major players when it comes to producing standards that are used for various applications in the modern world. One of their standards that is used worldwide is NFPA 70, or the National Electrical Code, more commonly referred to as the NEC.

There is also NFPA 70B, which applies to maintenance standards for electrical equipment that are also interwoven into the NFPA 70E standard. The final piece is NFPA 70E, which is the commonly used standard in the United States for electrical safety, as well as being applied worldwide within certain industries. These include oil and gas production as well as paper production.

Protecting your employees from the dangerous hazards of Arc Flash:
  • Establish a facility electrical safety program with clearly defined responsibilities.
  • Appoint an electrical safety program manager.
  • Provide proper Arc Flash/Electrical Safety Training for any workers exposed to 50V or more.
  • Conduct a facility Arc Flash Risk Assessment (Hazard Analysis) to determine what degree of arc flash hazard is present.
  • Up to date labeling of equipment to warn of potential arc flash hazards.
  • Ensure you have an adequate supply of properly rated arc flash protective clothing and equipment on hand, and that workers are using and testing, as required.
  • Ensure that you have the proper tools on hand for employees to safely perform electrical work.
  • Properly maintain all electrical distribution system components.
  • Update and maintain all electrical distribution documentation.
  • Stay up to date with the latest NFPA 70E Standard for Electrical Safety in the Workplace requirements (the code is updated every 3 years).

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