Preventing and Minimizing Arc Flash Risk

Following OSHA regulations and using good design can reduce the risk of damage to workers and equipment from arc flashes.

Arc flashes present a serious hazard involving electrical equipment that is more common than many would believe. Due to OSHA’s reporting requirements for arc flashes, they are under-reported or not reported at all. No one is certain how frequently they occur, but some sources estimate there are five to 10 electrical equipment explosions (aka arc flashes) each day in the U.S.

Most reports on electrical-related injuries focus on shock and electrocution, rather than arc flashes in which explosive forces, heat, and gasses cause the injuries and deaths, according to the National Fire Prevention Assoc. But research conducted across burn centers show arc flashes cause 34% to 55% of all the electrical burns received on the job.

It has been estimated that more than 2,000 workers are admitted to burn centers annually to be treated for severe arc-flash burns, and arc flash incidents kill one to two people every day. In addition to injuries and fatalities, arc flash also carries significant financial costs. Medical treatment for arc-flash injuries costs an average of $1.5 million per incident, which is borne by the factory owner. This makes arc-flash prevention and risk reduction a high priority when designing electrified equipment.

Labels indicate boundaries around electric enclosures and levels of personal protective equipment  for working inside it.

Arc Flashes vs. Arc Faults

An arc flash is the explosion caused by a phase-to-phase or phase-to-ground short circuit. Arc flashes emit extreme heat, intense light, and violent pressure blasts. In comparison, an arc fault is the high-power discharge that causes the short and triggers an arc flash. Arc faults can be caused by several different conditions, including a faulty wire, a loose fuse, a tool dropped into a live cabinet, or even personal contact with live components.

Arc flashes pose a significant risk for bodily harm from the force of the explosion, heat of the blast, and the corrosiveness of the gasses. Physically, the pressure of the explosion can be as much as 10,000 psi, which compares to the force of a high-speed collision.

In addition to its explosive force, arc flashes carry high temperatures and can reach up to 35,000°F, which is hotter than the surface of the sun. Arc events also create noxious and corrosive gasses that, if inhaled, increase the chances of catastrophic injury or death.

Arc-Flash Regulations and Standards

The Occupation Safety & Health Administration (OSHA) is the governing body that regulates workplace safety, including arc flash prevention, equipment labeling, and use of personal protection equipment (PPE). Specific standards related to arc flash include OSHA 1910.137 for electrical protective equipment and OSHA 1910.269 App E on protection from flames and electric arcs.

 The National Fire Prevention Association’s standard NFPA 70E covers safety-related work practices, maintenance requirements, and special equipment requirements. Companies that comply with NFPA 70E must conduct an Arc Flash Risk Asessment, sometimes called an Arc Flash Study or Arc Flash HazardAnalysis. The review determines safe work practices, arc-flash boundaries, and appropriate levels of PPE to be used.

Underwriters Laboratory also has a standard specifically for industrial control panels and switchgear (manufactured and modified). It covers control panels intended for general industrial use and operating at 600 V or less. Equipment meeting this standard is installed in “ordinary” locations in accordance with the National Electrical Code, ANSI/NFPA 70.

As the governing body for workplace safety, OSHA regs are the driving force for compliance in the U.S. Manufacturers that do not meet the regs can be fined by OSHA and lose their insurance. With OSHA issuing fines and penalties when workers are put at risk for arc flash injuries, a common misconception arose that the agency enforces NFPA 70E. Although companies are not specifically required to comply with NFPA 70E, it acts as an outline on how to ensure compliance with OSHA’s arc flash safety regulations.

A Closer Look at NFPA 70E

NFPA 70E sets arc flash boundaries for organizations, including keeping 3 ft away from cabinets with electrical circuits running at less than 750 V and keeping 19 feet away from cabinets holding circuits running at 15,000 to 36,000 V. Boundaries are delineated by tape or a chain and show the safe distance from cabinets for workers without PPE.

Arc flash boundaries vary with the risk level and the voltage of the equipment. For instance, a “limited” range is for minimal shock hazards from electrical overarcs; a “restricted” range is for increased shock risks; and a “prohibited” range entails significant risks of direct contact with electrified components. Ranges for these boundaries are outlined in NFPA 70E table 2-1.3.4. and OSHA 29 CFR,1910.269 table R6.

Energized panels or boards must be marked with a danger or warning label that indicates the potential hazard and the level of PPE required (from 0 to 4). Category 0 PPE requires cotton, untreated fiber shirts and pants, safety glasses, and hearing protection. It warns against wearing polyester or synthetic fabrics near the equipment that could melt This category is for areas with the lowest potential for an arc flash event, but the standard warns against wearing polyester or synthetic fabrics that could melt near the equipment. At the other end of the spectrum, Category 4 protection includes an arc-rated suit, along with protection for face and head, hands, eyes, and hearing, as well as a hard hat and appropriate footwear.

Reducing the Risks

To minimize the possibility risk of an arc flash, follow OSHA’s lockout/tagout procedures. When followed closely, they can protect workers from hazardous energy release and from the unexpected energization or startup of machinery and equipment.

Lockout/tagout requires that machinery be turned off and disconnected from its energy source before anyone performs maintenance on it. It mandates that authorized individuals either lock or tag the energy isolating device(s) to prevent the release of hazardous energy. An authorized person must also take the required steps to verify energy has been isolated effectively. Lockout devices hold energy-isolation equipment in a safe or off position. They prevent equipment from being energized and can only be unlocked with a key. Tagout devices feature prominent warnings that are fastened to energy-isolating equipment to warn workers not to reenergize the equipment while it is being serviced. Details for using tagout devices are listed in the OSHA standard, The Control of Hazardous Energy (Lockout/Tagout), Title 29 Code of Federal Regulations Part 1910.147.

 The safest way to work on any panel is when the panel is turned off. If lockout/tagout is done correctly, maintenance staff can safely work on electric panels without risking exposure to arc flash.

An arc flash assessment, another required safety measure, determines both the potential and intensity of an arc flash. Calculations done in these assessments (found in IEEE 1584, Guide for Performing Arc-Flash Hazard Calculations) helps in creating appropriate training and procedures for anyone working with energized electrical parts, switches, breakers, or other equipment.

To minimize arc flash risks, it is critical to understand that NFPA 70E standards make it easier to comply with OSHA regulations. NFPA 70E outlines proper training and  procedures and PPE standards for manufacturers and their maintenance staff. In addition, engineers can design arc-flash prevention into enclosures so that they serve as the first line of defense. Using the isolated box approach, customized with appropriate accessories, manufacturers can prevent unsafe access inside enclosures. As manufacturers look to improve efficiency and safety of their operations, developing and executing proper arc flash prevention standards will ensure the health of their staff and their bottom line.

 

Click here to read the entire article from Machine Design.

Electrical burst kills Amtrak worker in the Bronx, article from NY Daily News

An electrical explosion killed an Amtrak worker in a Bronx power substation Thursday morning, officials said.

The explosion erupted about 11:30 a.m. in Con Ed’s Van Nest Yard, which the company shares with Amtrak, on Unionport Road near White Plains Road in Parkchester.

The Amtrak worker was electrocuted, according to police. Two other people suffered minor injuries, officials said.

Authorities cut the power and were on scene investigating.

Ron Seabrook, 76, who’s lived near yard for 30 years, said the workers should have been better protected from harm.

“Something had to be exposed for him touch something or do something for him to lose his life,” he said. “It makes me feel bad for that individual, whoever it was. I’m quite sure they felt they were safe.”

Click here for the full article from NY Daily News

OSHA fines Waukegan plant after explosion kills 4, including 3 from Kenosha Count

OSHA fines Waukegan plant after explosion kills 4, including 3 from Kenosha Count

Investigators continue to search for one missing person in the rubble of the former factory.

WAUKEGAN, Ill. — The Occupational Safety and Health Administration (OSHA) has fined an Illinois plant following an explosion that killed four workers.

The Waukegan-based company, AB Specialty Silicones, is facing $1.59 million in fines for 12 federal safety violations after four employees were killed in an explosion on May 3, 2019. Three of the four killed were from Kenosha County.

OSHA investigators determined that “AB Specialty Silicones failed to ensure that electrical equipment and installations in the production area of the plant complied with OSHA electrical standards, and were approved for hazardous locations.”

The Principal Deputy Assistant Secretary of Labor for Occupational Safety and Health Loren Sweatt said, “By ignoring safety and health requirements, this employer created an unsafe work environment with deadly consequences.”

Click here for the entire story from WTMJ-TV Milwaukee

Construction worker critically injured in electrical accident in Jacksonville

Jacksonville police say boom truck lifting traffic signal hit energized line

JACKSONVILLE, Fla. – A construction worker installing traffic signals Friday morning on North Kernan Boulevard in East Arlington was critically injured when a boom truck he was in hit a high power transmission line, according to the Jacksonville Sheriff’s Office.

The man operating the crane was doing electrical work for a subcontractor working on a Jacksonville Transportation Authority, tried to get off the truck but was shocked. Police said the victim was hospitalized in life-threatening condition.

Residents in the area heard what sounded like an explosion, smelled something burning and came outside to see what was happening.

“We got to the stop sign and there was a gentleman that had grabbed (the victim) and put him on the ground and started doing CPR,” Angela Ahern said. “(Paramedics) had to pull him away and when they did, he dropped to the ground and four guys got on the ground with him and held him. Every guy over there was crying.”

The JEA told News4Jax the utility has no record of a request from the subcontractor or the contractor, Superior Construction, to turn off power to the transmission lines in the area while the traffic lights were being installed.

According to the JTA, the man is an employee of James D. Hinson Electrical Contracting Co. Inc. The company told News4Jax it would not be making a comment.

JTA spokesman David Cawton II released a statement Friday afternoon:

“JTA’s main concern is the health and well-being of the subcontractor who was seriously injured today while working on the Kernan Blvd. improvement project, part of JTA’s MobiltyWorks program. We are fully cooperating with authorities as they investigate the cause of the accident.”

Police and the Occupational Safety and Health Administration were on the scene, investigating.

Click here for the story from WJXT News4Jax

2 dead, 2 others critically injured after a string of electrocutions in a single day

CBC News reports, Multiple electrocution incidents in Ontario prompt Electrical Safety Authority warning

Ontario’s Electrical Safety Authority is pleading with people to stay safe around power lines after two people were killed by electrocution and two others were critically injured in a single day in Ontario.

A worker was electrocuted and killed in Vaughan on Sept. 19 when a drill boom on a truck made contact with overhead power lines.

The authority said in a news release that the injuries stem from three incidents where workers on job sites came into contact with overhead electrical wires.

“This was a cluster of events that we haven’t seen before, and we don’t understand at this point in time if this was just an aberration,” said Joel Moody, chief public safety officer with the Electrical Safety Authority (ESA).

“What we do know is that these instances happened, and unfortunately there were two deaths and two critical injuries … and ESA wants to extend our condolences to those families who were affected by these incidents.”

The provincial Ministry of Labour has confirmed that one of the deaths happened just before 9 p.m. Thursday, when a worker died in Vaughan.

“A worker sustained fatal injuries due to an electrical contact when [a] drill boom made contact with overhead power lines,” said spokesperson Charlene Millett in a statement.

She said the worker was employed by Pontil Drilling Services, which, according to the business’s website, does work ranging from geotechnical and environmental drilling to utility locating.

The company declined a request for comment.

The ministry says it has issued six requirements to the drilling company and its investigation is still ongoing.

A second person died on Sept. 19 at a private residence in Kawartha Lakes, near Peterborough. The ministry says two self-employed workers were trimming a hedge in an elevated work platform when it made contact with a power line.

One person died, while the other sustained critical injuries, Millett said. Two ministry inspectors went to the scene, but no orders were issued.

The third electrocution happened on the same day in Scarborough, when a worker was injured when a tower crane hit an overhead power line.

The ministry says the employer in that case was construction company Darcon Inc. The company didn’t immediately respond to a request for comment.

“Our thoughts are with the family and colleagues of the workers who passed away,” Millett said. “Our investigation is ongoing.”

Minister of Labour Monte McNaughton said his “thoughts and prayers” are with the families and friends of the workers who died and were injured.

“Ministry officials are currently investigating these incidents,” McNaughton said in a statement. “We take them very seriously and are ensuring any concerns will be adequately addressed.”

According to the ESA, there are usually only two electrical deaths a year in Ontario on average, which makes two in a 24-hour period all the more unusual.

“Those two deaths are two deaths too many,” Moody said.

In the last 10 years, 19 people have died from electrocution in the province, he said.

All electrical incidents are preventable, he added.

The ESA recommends a number of tips when working around electrical wires, including watching for hidden power lines that can be hidden by foliage, being aware while driving dump trucks, and keeping equipment away from power lines.

 

Click here for the article directly from CBC News.