January/February 2014
Arc flash and other electrical hazards can injure or kill in an instant when workers are testing, maintaining, or repairing electrical equipment. To keep everyone safe, ensure workers are qualified, follow recognized safe work practices, and use the right PPE.
By Lee Marchessault
Electrical hazards exist in every scrapyard—and they can be a matter of life and death.
At one location, an electrical employee was working on a 480-volt main switch panel when he dropped an uninsulated Allen wrench. It fell and hit a live electrical part, causing it to short and creating an arc flash between the part and the ground.
An arc flash is when electricity arcing between two electrodes—or, in this case, from an electrode to the ground—creates an energy release so extensive that it charges the surrounding air, creating an explosion with massive heat, light, and pressure. Temperatures can reach 35,000 degrees F, which is hotter than the surface of the sun. This is hot enough to melt hardened steel, burn through the clothing and skin of people some distance away from the incident, and even vaporize some metals. The pressure of an arc flash explosion can throw a worker across a room or rupture eardrums, and the light can cause blindness.
The arc flash instantaneously burned through all of the worker’s clothing except for his leather boots. A fellow worker who came to his aid said he had never heard a man scream like that and would never forget the smell of burning flesh. The injured employee was in the hospital for 18 months, and he never returned to work as an electrician.
At another yard, a worker was opening a 4,160-volt electrical fuse cabinet that had a loose wire. The wire caused a short circuit and an arc flash that literally burned his face off. He’s had 13 surgeries so far to restore function to his face.
At a third location, an employee was working on a generator transfer switch, something he had done many times over the years, when he tripped, got his head caught between two live electrical parts, and was killed. In his truck was a hard hat designed to prevent electrical shock. If he had been wearing it, it would have saved his life, and he most likely would have walked away from the incident.
The Occupational Safety and Health Administration’s (Washington, D.C.) interest in electrical safety—specifically arc flash hazards—has grown in recent years, as has its interest in scrapyard safety. Protect yourself from both OSHA scrutiny and accidents that could ruin lives by having an electrical safety program that trains workers in assessing electric shock and arc flash risk hazards and using safe procedures—including protective gear—for repairing and maintaining electrical equipment.
Rules of the Road
Not long ago, checking for electrical hazards was a primitive affair. The 1953 American Electricians’ Handbook said it is “safe” to test circuits for the presence of voltage (up to 250 volts) by touching the conductors with one’s fingers. “Some men can endure the electric shock that results without discomfort whereas others cannot,” it reads. For very low voltages (24 volts), the manual said it’s best to test for the presence of voltage by touching the conductor with one’s tongue. These were accepted practices even though electrical voltage testers were available.
That’s no longer the case. The National Fire Protection Association (Quincy, Mass.) codifies requirements for safe electrical installations in the National Electrical Code, which many state and local governments use as the basis of their laws and regulations. The NFPA further outlines how to prevent injury from electrical shock, electrocution, arc flash, and arc blasts in alternating-current electrical systems in its Standard for Electrical Safety in the Workplace, also known as NFPA 70E, published in 2000. Updated regularly, the 2012 edition also covers electric shock and arc flash hazards in direct-current systems.
OSHA responded to NFPA’s heightÂened interest in arc hazard prevention with a 2007 update of its electrical regulations, which are based on NFPA’s standards and outlined in Occupational Safety and Health Standards, Subpart S (1910.302-308). It also increased its compliance activities related to electrical safety. Its compliance checks continue to focus on employee protection—first, to see if a facility has eliminated hazards through proper lock-out/tag-out procedures and other administrative controls or barriers; second, to see if workers have and use the proper personal protective equipment.
Who Is Qualified?
Not everyone in a scrapyard should be maintaining or repairing electrical equipment. Keep in mind that any voltage can kill. A standard 120-volt toaster oven can cause an electric shock that can result in serious injury or death. There have been fatalities related to working with 48-volt controls. Most heavy equipment in a scrapyard falls into the low- or medium-voltage categories. According to the Institute of Electrical and Electronic Engineers (New York), low is 600 volts or less; medium is between 601 and 38,000 volts. Automobile shredders, for example, are typically medium-voltage equipment, as some models operate with 4,160 volts or more. While most other common scrapyard equipment—balers, conveyors, grinders—typically falls into the low-voltage category (480 volts, or in Canada, 575 volts), workers must handle it just as seriously.
OSHA’s regulations state that only qualified workers should maintain electrical equipment and respond to possible hazards, but there is often confusion surrounding what it defines as qualified and which employees must meet that standard. For example, many companies hire licensed electricians to fill their maintenance needs, assuming that if they’re licensed, they must be qualified. This might be true, but often it’s not. Conversely, a qualified electrical worker doesn’t need to hold an electrician’s license or similar certification to safely perform his or her job. What about employees who do routine tasks like clearing dust from around the equipment, checking for loose or frayed wires, or testing the equipment to see if it’s functioning properly? They should be qualified, too. There are many levels of qualified workers. One worker might be qualified to work in control cabinets but not main switchgear, for example. Each worker at a facility must be qualified to perform the electrical work he or she will be expected to do.
OSHA defines a qualified worker as “one who has received training and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved.” The two key parts of that definition are “received training” and “demonstrated skills and knowledge.”
For example, qualified workers must be able to distinguish exposed live electrical parts from other parts of electrical equipment, determine the nominal voltage of exposed live electrical parts, and know the clearance distances for various nominal voltages (what NFPA 70E calls the restricted approach boundary). They also must understand several special precautions related to capacitors, current transformers, lighting requirements, gradient potential (for medium and high voltage), PPE requirements, and emergency response for electrical contacts.
Employees who have demonstrated their skill at handling electrical equipment and received appropriate training in assessing and preventing electrical hazards can be designated qualified workers. But make sure to document a qualified worker’s skills, knowledge, and training because OSHA will check for this, especially if it has identified a deficiency in work practices or procedures at the facility.
Job Briefings
For each piece of electrical equipment, OSHA requires a facility to have a written general hazard assessment that includes the PPE required for operating that machine. Before they do any maintenance, repair, or troubleshooting work on that equipment, qualified workers also must conduct a pre-work personal hazard assessment, also called a job briefing, to identify existing conditions that pose actual or potential safety hazards and determine the appropriate level of PPE needed for the task, such as hard hats, safety shoes, safety glasses, gloves, and hearing protection. The most specific recommendations—and the recognized industry standard—are in NFPA 70E. OSHA’s rather broad rules regarding electrical PPE are in 29 CFR 1910.132; in Subpart S, 1910.335(a)(1); or in 1910.269 for work related to generation, transmission, or distribution of electricity, usually associated with medium- and high-voltage work. OSHA has also cited companies for noncompliance under its general-duty clause, which says companies must follow the industry standards, which in this case is NFPA 70E.
The qualified workers—who could be electricians, facilities maintenance workers, or line workers who are responsible for routine maintenance and troubleshooting—must do a job briefing prior to the start of each shift as well as when hazards are discovered while working. Briefings can be concise if the task is routine and the equipment is known to be in good working order; they can be more extensive if a job is complex or especially hazardous, or if the work is not done on a regular basis. Whether an employee is working alone or is supervising a crew, using a written checklist during the job briefing is considered a best practice to ensure proper procedures and precautions are taken.
The best rule to keep in mind when performing job briefings—and before beginning any work—is to stop, plant your feet for 30 seconds, and think about what it is you need to do. People often perform the same tasks over and over again, so they become routine and second nature. It’s when they do something different or don’t think a job through before they begin that they get hurt.
Preventing Electrical Shock
The two primary hazards associated with electrical equipment are electric shock and arc flash. The job briefing for a particular piece of equipment should identify its nominal voltage, which is the information needed to determine shock-prevention measures. The best shock-prevention measure is to completely de-energize the equipment or enclosure before opening doors or removing covers, though this is not always feasible. Other prevention measures include appropriate PPE and maintaining the minimum approach distance recommended to safely work on the equipment. Clean air is a great insulator, so distance and nonconductive barriers are best to avoid contact and, in some cases, eliminate the need for electrical PPE. For example, when working in a control cabinet with 24 volts, place a rubber barrier over the incoming 480 volts at the breaker and transformer. This will then allow troubleshooting of the 24-volt equipment without the need for rubber gloves, which would be required if the 480-volt parts were left unguarded.
Keep in mind that electricity must complete a circuit to flow, and electric shock occurs when a body part or something that conducts electricity to the body becomes part of that circuit. The goal of protective equipment, then, is to increase resistance through the human body, particularly at the part of that circuit where such contact could occur, to minimize the voltage flowing through it. Head-to-toe protective equipment against shock hazards includes electrical-hazard-rated hard hats (Type 1 Class E and/or Type 2 Class G), rubber insulating gloves rated for the voltage exposure, and electrical-hazard-rated boots. For 480- and 575-volt work, uninsulated body parts must remain outside the minimum approach distance of 12 inches. OSHA defines MAD as “arm’s reach plus 12 inches” for these voltages. That means anything that’s within arm’s reach of the cover—plus 12 inches beyond that point—must be insulated to protect against electrical hazards.
Workers should put on the PPE before opening a door or removing a cover to exposed parts. It’s required even when equipment is de-energized because the qualified worker must test the equipment to be sure it’s de-energized. Class 0, 14-inch rubber gloves with leather protectors are the best option for low-voltage work. Although lower-rated, Class 00 gloves are approved for use up to 500 volts, that might not be enough protection because utilities are allowed to provide 5 percent more or less voltage than specified, so 480-volt systems could actually exceed 500 volts. The length of the glove is also important: 12-inch rubber gloves are not long enough because the lower arm will be within the minimum approach boundary when testing using a meter.
Workers must air-test rubber gloves at the start of every shift. A hole the size of a pinprick can remove the shock protection gloves provide and could contribute to a fatality. To do an air test, inflate your gloves by rolling the cuff to capture as much air as possible or by using a special rubber glove pump, then check for any holes. Gloves also must be lab tested at least every six months to ensure the insulated value of the gloves has not broken down. To make the testing easier, it’s best to have two pairs of rubber gloves for each worker: one at the facility and one at the test lab. At the five-month mark, ask your lab to test the second set and ship them to the facility. When you receive them, the employees ship the set they’ve been using back to the lab. It also might help to have the sets in different colors to ensure workers are using gloves tested in the proper time frame. Thin cotton liners soak up sweat, and they come in handy if workers share gloves. Leather protectors are recommended to protect Class 0 rubber gloves and required when using Class 1 to 4 gloves.
When working on medium-voltage equipment, such as shredders or crushers, higher-rated gloves are required, as are hot sticks (insulated poles on which you test and install temporary protective grounds at a greater distance from a shock hazard). Other tools that every electrical worker should have include insulated hand tools, insulated fuse pullers, portable ground fault circuit interrupter cords (pigtails) for cord and plug tools, rubber barrier material, and UL-listed category III and/or IV test meters.
Arc Flash and Blast Protection
Work processes and PPE that protect workers from electric shock hazards are not sufficient to protect against arc flash and arc blast hazards. Again, the best protective measure is to de-energize the equipment. If that’s not possible, to determine the level of hazard and the proper protective measures, you need to know a piece of equipment’s incident energy, which is measured in calories per square centimeter. Qualified electrical employees must wear clothing that has a rating in cal/cm² that is greater than or equal to the calculated level at the working distance, typically 18 inches from the equipment for 480- or 575-volt work. The flash protection boundary is the distance from the equipment where the incident energy level is below 1.2 cal/cm². Incident energy levels above 1.2 cal/cm² will cause a second-degree burn to bare skin. You must install a barricade—such as “danger” barricade tape—at the flash protection boundary if it’s beyond the limited-approach shock boundary within which nonqualified workers otherwise would not be allowed.
For most day-to-day work (not including main switch gear, motor-control centers, transfer switches, or medium-voltage equipment), the simplest way to comply with arc-rated clothing requirements, as outlined in NFPA 70E Annex H, is to have qualified workers wear 8 cal/cm² flame-resistant clothing on a daily basis. A less effective option is to have them wear coveralls of that rating over cotton clothing. Workers also should wear an arc face shield for any work where the incident energy is determined to be greater than 1.2 cal/cm² and less than 8 cal/cm² or up to 12 cal/cm² where an engineering study has been done. For added face and neck protection when the calculated hazard exceeds 4 cal/cm², an arc-rated balaclava hood is required. Other recommended PPE to protect from arc flashes and blasts includes plastic-rimmed safety glasses worn under the face shield and arc-rated earplugs. For work with higher identified hazard levels—such as that related to main switch gears, large- and medium-voltage equipment, motor control centers, and lengthy high-amperage bus ducts—a 40 cal/cm² suit should be worn. Any work required on equipment where the hazard level is greater than 40 cal/cm² needs the equipment to be de-energized, or hazards should be engineered out via remote working procedures. A full engineering arc-flash study will provide accurate hazard information for labels and identify the level of PPE needed to work safely on the equipment.
Have a Plan
Though the hazards of working with electrical equipment are serious, protecting workers from electrical shock, arc flashes, and arc blasts doesn’t have to be complicated. Identify and document the hazards and eliminate or engineer out as many as you can. If eliminating the hazard is not feasible, protect employees—including contract workers—by knowing which ones need to be qualified and providing the training and evaluation that will make them qualified. Document the hazards, train workers, verify the program works, and enforce it. That’s your best defense against an OSHA citation, a lawsuit, or an accident that could end someone’s life.
Lee Marchessault is president of Workplace Safety Solutions (Williston, Vt.). For more information, e-mail him at lee@wssi.biz.
Arc flash and other electrical hazards can injure or kill in an instant when workers are testing, maintaining, or repairing electrical equipment. To keep everyone safe, ensure workers are qualified, follow recognized safe work practices, and use the right PPE.