Arc Flash Accident - Causes and Preventions

By R.W. Hurst, The Electricity Forum

Arc Flash Accident

An arc flash accident is a dangerous electrical event that occurs when an electric current jumps across the gap between two conductors, creating an electrical arc. This can happen when an electrical system is overloaded, damaged, or improperly installed or maintained.

An explosion can release an enormous amount of energy in a fraction of a second, generating extreme temperatures that can cause serious physical harm or death to anyone in the vicinity. The intense heat and light produced by an arc flash can cause severe burns, vision damage, and hearing loss and even trigger explosions and fires.

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An arc flash occurs in a variety of settings, including industrial and commercial facilities, power generation and distribution sites, and even residential homes. To prevent an arc flash accident, it's important to follow proper electrical safety procedures, wear appropriate personal protective equipment, and have electrical systems regularly inspected and maintained by qualified professionals.


Fatal Work-Related Electrical Losses, 1992-2019

Data on fatal electrical accidents is available from the Census of Fatal Occupational Injuries (CFOI), introduced by the Bureau of Labor Statistics to create a comprehensive count of fatal occupational hazards in the United States through the use of multiple source documents. CFOI collects information on fatal workplace events in each state from multiple source documents, including death certificates, workers’ compensation records, data from federal agencies, and newspaper reports, and uses them to assemble a comprehensive fatality profile of workers.

The use of multiple information sources is credited with the creation of a more comprehensive injury database than would be available through a single data source, and CFOI, for this reason, has been endorsed by both the National Safety Council and the National Center for Health Statistics as the data source for fatal worker losses. (U.S. Bureau of Labor Statistics) Between 1992 and 2019, CFOI recorded 5587 fatal electrical events, an average of 254 fatal electrical occurrences each year. Of these, 5527 (99% of the total) were reported to be electrocutions, while less than one percent of the fatalities, 12 were due to burns.

The sum of electrocutions and burns is slightly less than the total number of electrical accidents because some information for some events may not be reported or because the data do not meet publication criteria. It should be noted that the data for 2019 is preliminary data, and the total number of ocurrences could increase if additional fatalities are reported before the data is finalized.



How Is an arc flash accident caused?

Arc flash accidents are caused by an electric current passing through the air between two conductors, resulting in an arc of electricity. This can happen when electrical equipment or systems are overloaded, damaged, or improperly installed or maintained.

Some specific causes of arc flash accidents include:

  1. Overloading: Too much electrical current flows through a circuit can cause an explosion. This can happen when equipment is overloaded, circuits are improperly designed or installed, and an arching fault occurs.

  2. Aging or faulty equipment: Electrical equipment, such as switches, circuit breakers, and transformers, can deteriorate over time or become faulty, increasing the risk of an explosion.

  3. Human error: Accidentally touching a live conductor, dropping a tool onto exposed electrical parts, or improperly maintaining electrical equipment can cause accidents.

  4. Environmental factors: Environmental factors such as dust, moisture, and corrosion can also increase the risk of an explosion by creating a conductive path between live conductors or components.

To prevent arc flash accidents, it's important to design and install electrical systems properly, provide regular maintenance and inspections, and ensure that workers are trained in electrical safety procedures and wear appropriate personal protective equipment.


What losses are caused by an arc flash?

An arc flash is a dangerous electrical explosion that can occur when an electrical current is accidentally or intentionally disrupted, causing a release of energy in the form of an arc. Arc flashes can cause serious physical harm, including:

  1. Burns: Arc flashes can produce extreme temperatures that can cause severe burns to the skin and eyes. The heat can be so intense that it can cause clothing to catch fire, leading to even more severe burns.

  2. Hearing Loss: The sound of an explosion can be as loud as a gunshot, which can cause hearing damage, including tinnitus or permanent hearing loss.

  3. Vision Loss: An explosion's intense light and heat can cause temporary or permanent vision loss. Even if the flash is brief, it can cause "flash burns" on the cornea, which can be painful and cause temporary blindness.

  4. Shrapnel: An explosion can create a powerful blast that can create shrapnel damages from flying debris, resulting in cuts, bruises, and fractures.

  5. Cardiac Arrest: The electrical shock from an arc flash can cause cardiac arrest, which can be fatal.

  6. Psychological Trauma: Arc flashes can be traumatic experiences, and they can cause emotional and psychological trauma, such as anxiety, depression, and post-traumatic stress disorder (PTSD).

It is important to prevent accidents by taking proper precautions when working around electricity to minimize the risk of explosion and other electrical accidents.


How can an arc flash accident be prevented?

Arc flash accidents can be prevented by implementing proper safety measures and following established best practices when working with electrical equipment. Here are some steps that can help prevent arc flash accidents:

  1. Conduct a hazard analysis: Before beginning work on electrical equipment, conduct a thorough hazard analysis to identify potential risks and take steps to mitigate them.

  2. Use proper personal protective equipment (PPE): Employees working with electrical equipment should wear appropriate PPE, including flame-resistant clothing, insulated gloves, and eye and hearing protection.

  3. Use proper tools and equipment: Use proper tools and equipment designed for the task at hand and specifically rated for the voltage and current levels.

  4. Follow proper lockout/tagout procedures: Lockout/tagout procedures should be followed when working on electrical equipment to ensure that the equipment is de-energized and cannot be accidentally or inadvertently turned on.

  5. Provide proper training: Employees should be properly trained in electrical safety, including the hazards of explosions and how to prevent them.

  6. Follow established best practices: Follow established industry best practices and standards for electrical safety, including the National Fire Protection Association (NFPA) 70E and Occupational Safety and Health Administration (OSHA) regulations.

  7. Regular maintenance and testing: Regular maintenance and testing of electrical equipment can help identify potential issues before they lead to an incident.

By following these steps and implementing other best practices for electrical safety, the risk of accidents can be minimized.


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