Importance of Arc Flash Hazard Analysis – Is Arc Flash Study Crucial in Power Systems Industries?

Do Arc flash studies really matter? Or the fact about how Power Systems Engineers can reduce the risk of Arc flash hazards in commercial facilities and industries?

This guide will provide a detailed overview on the importance of Arc flash hazard analysis.

We will also take a look at some of the most recent Arc Flash incidents their causes and how we can reduce the risk of Arc Flashover?  

Importance of Arc Flash Study in Electrical Facilities

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An Arc flash is an electric arc or arcing fault in which an electric current passes through the air in an electrical power system's equipment from one live conductor to another or to the ground.

Arc flash hazard is the danger of a serious burn injury due to this arcing fault. Most of the employers are not familiar with the consequences of Arc flash hazards and the penalties imposed by OSHA (Occupational Safety & Health Act).

Treatment costs for burn (2nd and 3rd degree), victims can approach $500,000/mo. A workplace fatality can cost an estimated $8.5 million plus penalties also.

The NFPA70E (National Fire Protection Association) recommends to perform arc flash study every 3 years to reduce the risk of electrical hazards and make the workplace safe to perform any electrical analysis.

The labeling of panels and electrical equipment is also required by the National Electric Code (NEC). OSHA, in cooperation with the NFPA, requires that employers determine and document arc flash information for protection of working personnel.

Aftermath of Arc Flash – What Happens Exactly When Arc Flash Occurs?

When an arc fault occurs, it is followed by an arc flash and arc blast immediately. These are hazardous explosions that can damage the surrounding materials as well as cause injuries and even death. The enormous temperature levels of the arc ionize the nearby air and heats surrounding metals.

For instance, copper metal is expanded by 67,000 times while being converted from solid to gas. Due to extreme temperatures and thus expansion, the pressure rises significantly and leads to dangers like increased light, heat and sound intensity, and shrapnel.

Arc flash is the emission of light and heat and arc blast is the intense pressure upsurge that occurs.

The arc flash temperatures can rise up to 35,000 degrees Fahrenheit. The temperature of the surface of the Sun is 9,941 degrees Fahrenheit. By comparing these two temperatures, we can contemplate just how deadly an arc flash event can be.

These temperatures can cause burns to the human body and even the clothing can catch fire. Flammable and combustible materials can be ignited and would worsen the situation.

The harmful light intensity can damage the eyes and can even cause blindness. The excessive sounds also cause damage to hearing and listening abilities.

The arc blast pressures can knock off personnel working nearby. The equipment present in the vicinity of the arc flash can burst and the shrapnel and debris are blown on higher speeds and pressures.

Together, the arc flash and arc blast can damage human organs like lungs and other soft tissues.

Now, we will review some of the major arc flash incidents in the recent years and analyze the cause of those incidents cited by OSHA (Occupational Safety and Health Administration) and other organizations.

1: Employee, Shocked By Electric Arc, Falls From Roof And Is Killed.

Around 11:00 a.m. on March 12, 2020 at C & T Building Technologies, LIC, Employee #1, employed by a construction company, was working at the renovation of a two-story commercial building. He was on the roof and using a steel tape measure in preparation for installing a piece of sheet metal roofing.

The wind blew the extended part of the tape measure into an overhead power line that was transmitting 19,920 volts of electricity. An electric arc occurred, which burned and shocked Employee #1 and caused him to fall from the roof, a fall height of 25 feet. The impact of the fall resulted in blunt force traumatic injuries to his head and torso. Employee #1 was killed.

You can further read the complete details of this arc flash incident on the given link. Click here !

2: Employee Sustains Multiple Burns When Caught By Electric Arc

At 10:00 a.m. on March 31, 2019, an employee was assisting a coworker with troubleshooting an electrical issue with one of the process machines at Cartel Electronics Inc.

The employee inserted a wire brush into an exposed electrical panel to clean the contacts of a breaker and caused an arc flash explosion, sustaining severe second and third degree burns on his hands, arms, face, neck, and head. The employee was hospitalized.

You can further read the complete details of this arc flash incident on the given link. Click here !

3: Arc Flash Incident On Electrical Distribution Panel – Electrician Burned with 3rd Degree Burn

This arc flash incident occurred on March 15, 2018 at Nations Electric, Inc. where an Electrician was given a work to install Circuit Breakers on a live 480 volts distribution panel in a switchgear area.

The panel cover was open and an employee with a screwdriver in hand made direct contact with the bus bars, when suddenly the screw driver slipped from his hands and fell inside the electrical panel, due to which an arc flashover occurred, and he suffered 2^nd and 3^rd degree burns to his arm and face.

The employee was immediately transferred to the hospital for intensive care.

You can further read the complete details of this arc flash incident on the given link. Click here !

4: Arc Flash Incident on Nuclear Power Plant site – Two Employees Suffered Burns

This Arc flash incident occurred at the Tennessee Valley Authority Nuclear Power Plant owned by Day & Zimmerman Inc.

The incident took place when two of their employees were busy pulling a live electrical cable from the bus duct of the distribution panel, during which the cable end made accidental contact with the live bus bar resulting in the employees suffering severe burns from the subsequent arc flash.

Although, after comprehensive analysis of the incident, it was found that these serious injuries could have been prevented if the company had implemented effective work practices and urged the employees to wear the minimum arc rated PPEs (Personal Protective Equipment);

OSHA cited the Chattanooga-based company for failing to fulfill the requirement of employees wearing the recommended PPEs, conducting pre-job briefings with employees on energy source controls; removal of a ground and test device; and allowing potential for residual electrical energy to accumulate.

As a result of the Arc flash incident, the company faced $71,599 in proposed penalties.

You can further read the complete details of this arc flash incident on the given link. Click here !

5: Arc Flash Incident at an Integrity Windows Plant– Electrician Injured with Severe Burns

This arc flash incident occurred at the Integrity Windows plant located in North Dakota state of the United States.

The arc flash occurred when an electrician was installing and testing circuit breakers at the plant on a three phase system (400 volts).

After further investigation, it was found that he was wearing insulating gloves with leather protectors and using an arc flash face shield, but without any balaclava or arc flash suit.

The unfortunate thing over here is that the incident could have been prevented and his life could have been saved had the electrician worn an arc flash suit and hood matching the incident energy rating of that system.

The above incidents highlight the importance of NFPA 70E and OSHA training and emphasize their role in developing a safe workplace and qualified personnel.

IMPORTANT NOTES:

Under the Occupational Safety and Health Act (OSHA) of 1970, employers are responsible for providing safe and healthful workplaces for their employees.

OSHA's role is to help ensure these conditions for America's working men and women by setting and enforcing standards, and providing training, education, and assistance.

For more detailed information, you can visit their official website here !

Also, the National Fire Protection Agency (NFPA) standard for electrical workplace safety, NFPA 70E recommends to perform Arc Flash study every three years in an effort to keep employers, electricians, technicians, workers etc. safely in compliance with OSHA 1910 Subpart S and OSHA 1926 Subpart K.

The standard aims to reduce on-the-job exposure to shock, arc flash and arc blast.