The Danger of Arc Flash

By ELIZABETH FORD BURKHART

The following is an excerpt from a summary report of a National Institute for Occupational Safety and Health (NIOSH) Illinois firefighter fatality investigation:

“On June 11, 1999, a call came into central dispatch at 1300 hours reporting smoke coming from the electrical closet on the second floor of a large department store. After checking the store, the chief was informed there was no fire; however, the store lighting was not operable.

“The chief engineer of the department store had called an electrician to evaluate the situation. The electrician, an assistant chief with the Fire Prevention Bureau, and the assistant building engineer of the store entered the engineering room to check the problem. After checking the emergency power system, the electrician moved to the circuit breaker compartment (480 volts, 200 amps), removed the cover panel, and proceeded to test the circuits. Initial testing showed power on all terminals.

“When the electrician started to test the circuits again, a fault occurred, resulting in the formation of a fireball, seriously injuring the assistant building engineer and fatally injuring the assistant chief and the electrician.”

TWO DEATHS PER DAY

An arc flash is an electrical release of energy hotter than the surface of the sun and capable of exploding with the strength of eight sticks of dynamite. It kills two workers a day, every day, year in and year out; arc flash injuries occur 1,000 times more often than a shark attack. A shark attack receives front page coverage in the newspaper; an arc flash fatality doesn’t make the news at all.

An arc flash results from the sudden release of electrical energy through the air and usually occurs during routine maintenance. It can result from the following:

  • Coming too close to a high-amp source with a conductive object.
  • Dropping a tool or otherwise creating a spark.
  • Equipment failure from using substandard parts, improper installation, or even normal wear and tear.
  • Insulation breaks and gaps.
  • Dust, corrosion, and other impurities on the conductor’s surface.

Arc flash injuries result in severe skin burns. Additional injury may come from droplets of vaporized metal hitting the worker and those near the flash. Severe burns from ignited clothing may occur, and eyesight damage from high-intensity flashes is not uncommon. Hot gases can injure lung tissue, which can take weeks or months to heal. The psychological damage from these incidents can result in depression and job apprehension.

Typical arc flashes can occur when an employee mitigates a power outage and attempts to start a backup generator. They can result from spontaneous equipment failure during normal operations or from accidentally bridging two live electrical contacts with a conducting object, like a metal screwdriver or wrench. Other causes may include improper multimeter use, poor housekeeping that allows conductive dust buildup, and severe corrosion that allows connections to break. Since these incidents may occur when you perform routine maintenance, emergency responders and firefighters must understand the safe approach distances to exposed electrical conductors.

ARC BLASTS

Produced by a high-energy arcing fault, an arc blast is a wave and sound blast carrying considerable pressure. Pressure on the chest can be so great as to cause lung collapse. In some cases, the pressure wave has the energy to snap 3⁄8-inch steel bolt heads and knock over construction walls. It can also send metal parts flying at speeds of more than 700 miles per hour. Arc blasts can cause the following injuries:

  • Loss of memory or brain function from concussion.
  • Hearing loss.
  • Shrapnel wounds from metal parts.
  • Physical injuries, such as being blown off ladders, into walls, and so on.

Arc flash safety cannot be ignored, especially when one incident can cost as much as $15 million. Add to this the incalculable physical and emotional cost to the worker and his family. An often neglected victim is the witness to the effects on a coworker from an arc flash injury.

The magnitude of this problem is far reaching, and the following statistics are staggering:

  • 44,363 electricity-related injuries occurred between 1992 and 2001.
  • 27,262 nonfatal electrical shock injuries.
  • 17,101 burn injuries.
  • 2,000 workers admitted annually to burn centers for extended arc flash injury treatment.

WHO’S RESPONSIBLE?

An arc flash accident usually results from a combination of factors. Employers carry a responsibility to provide thorough, continuing education promoting personal safety and awareness for their supervisory personnel and workers. NIOSH states that employers have the ability to provide workplace safety analysis and to develop engineering controls to eliminate hazards.

Once an employee is made aware of the training provided by the employer, responsibility falls to the employee to protect himself from the potential consequences of not following approved practices. The employee must recognize that he is as responsible as the employer for lowering the number of incidences, fatalities, and severe injuries and lost production.

NFPA 70E AND NFPA 1500

The National Fire Protection Association (NFPA) created NFPA 70E, Standard for Electrical Safety in the Workplace, in 1979 as a sister code to NFPA 70, National Electric Code. NFPA 70 primarily deals with issues relating to the installation of equipment and systems to ensure safe operation; NFPA 70E deals with safe worker practices for performing maintenance on these systems. The 2004 edition deals specifically with arc flash and contains a developed and systematic approach to dealing with arc flash hazards. This includes methods of determining the stored potential energy of electrical equipment and providing a means of accurately labeling these hazards in the field.

NFPA 1500, Standard on Fire Department Occupational Safety and Health, prepares firefighters to safely control the hazards they face, including arc flash. Firefighters entering areas with arc flash potential must be aware of the danger and the protocol that must be followed. Exposure to shock hazards and electrocution risks are common and real. Personal protective equipment for arc flashes and arc blasts are similar to firefighter bunker gear.

Inspections of potential areas which could result in arc flash are vital. NFPA 70E, article 130.3 states: “A flash hazard analysis shall be done in order to protect personnel from the possibility of being injured by an arc flash. The analysis shall determine the flash protection boundary and the personal protective equipment that people within the flash protection boundary shall use.”

An inspection must include an arc flash study handled by a competent professional to ensure NFPA 70E compliance. Local firefighters must be aware of the need for these inspections and mandate them.

With training provided by a competent, trained professional, you can reduce arc flash hazards in severity and frequency. Extending arc flash hazard training to firefighters can prevent additional injuries.

REFERENCES

1. CapSchell, Arc Flash and Electrical Safety News, May 27, 2008.

2. National Institute for Safety and Health, “Arc Flash Awareness—Information and Discussion Topics for Electrical Workers,” National Electrical Manufacturers Association, September 2007.

3. Industry Applications Conference (IAS), 2005. Fourtieth Annual IAS Meeting. Volume 3, Issue 2-6, Oct. 2005, 1919-1923.

4. National Institute of Occupational Safety Hazards summary report. http://www.nfpa.org/assets/files//PDF/Member%20Sections/BFSS_3.pdf.

ELIZABETH FORD BURKHART is a former consultant for Sargent Safety, a Pittsburgh-based organization that specializes in training to prevent fire-related tragedies. She is currently a freelance writer producing articles for special interest groups. She has a master’s degree in corporate communication from Duquesne University and a B.S. in leadership and administrative development from La Roche College.

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