Prevent Electrical Hazards 'In a Flash'
Safety programs and proper arc flash equipment can help in avoiding injury.
WORKING with electrical systems exposes utility workers to an average of five to ten explosions of energy every day. When working with these same electrical systems at height, there is no room for error. The National Fire Protection Association and the American Society for Testing and Materials outline several guidelines and safety practices that should be employed in every situation. However, it is the responsibility of safety managers, contractors, and, most importantly, individual workers to employ effective safety programs and use personal protective equipment to help protect themselves and their co-workers from electrical and fall hazards.
A fiery explosion that emits a dangerous amount of concentrated radiant energy, arc flash is one of the most common hazards utility employees face when working with electrical equipment. Able to produce a blast wave equivalent to several sticks of dynamite, an arc flash produces effects that can be deadly and may include damaged hearing or eyesight and severe burns, not to mention the staggering financial costs that result from these accidents.
Arc flash can be caused by a simple workplace incident, such as dropping a tool or failing to lock out the source. Even the buildup of dust, impurities, or sparks produced during routine maintenance, including fused switch operations, can cause an arc flash. The temperature of these deadly explosions can reach more than 5,000 degrees Fahrenheit, and the outward force of an arc flash spreads hot gases, melting metal and other debris.
To reduce the risk of arc flash injuries and citations from oversight organizations, contractors should actively enforce an effective safety program that provides workers with the knowledge to assess arc flash risks and the correct level of personal protective equipment. For utility technicians who work at height around electrical systems, training programs and protective equipment should include industry-specific fall protection gear.
The best way to control the physical harms and costs of arc flash is to prevent it. It is the responsibility of the work site manager and overseeing company to ensure employees are knowledgeable and informed about the dangers of working with electrical systems, preventative measures that should be taken to avoid hazards, and the correct PPE that should be worn at all times. Not only will having this knowledge safeguard workers, but also it can sidetrack the potential for hefty fines from OSHA and other regulatory organizations.
Industry Standards: 70E, NEC
Many manufactures and companies offer compliance and safety training programs to help managers and workers understand arc flash and fall hazards. Options from which safety managers can choose include on-site training services, inviting consulting experts to determine which training and safety equipment are necessary, and traveling to a training center to obtain skills that can be passed on to co-workers. Courses not only should deliver information and knowledge of safety standards and compliance techniques, but also should also test the skills of those taking the class and the safety of their work sites.
Training programs also should teach safety managers and electricians how to gauge the dangers of each task and how to correctly read the labels on electrical equipment to determine what types of PPE are necessary. NFPA's 70E standard, which is accepted by OSHA as the industry standard, requires every employer of electrical workers to perform a hazard assessment for any task above 50 volts to be performed where there is the potential of an arc flash incident. To do this, the manager must consider the circuit voltage, maximum fault current, arc gap, distance from the worker to the arc source, and maximum arc duration.
Correct labeling can aid in the assessment. As provided by the National Electric Code® 110.16, all panel boards, industrial control boards, motor control centers, and other electrical equipment that may require maintenance, servicing, or adjustments while energized should be field marked to warn qualified persons of potential electric arc flash hazards. The marking should be located so it is clearly visible to qualified persons before they work on the equipment. Basic labels alert workers to potential hazards with "Warning" or "Danger." The latter is reserved for the most extreme situations. More specific write-on labels indicate the flash protection boundary, hazard category, and specific PPE that should be worn.
When an arc flash label is spotted, utility workers should immediately employ a lockout/tagout system before working with the electrical system. Lockout/tagout refers to specific steps taken to disable machines of energy, thereby safeguarding employees against the unexpected release of hazardous energy during service or maintenance activities. This should occur before any maintenance on an energized system is begun. Several steps are involved, including shutting the equipment down, isolating the machinery, applying a lock and tagging the energy source with a label, and verifying the energy source is disabled.
But because unexpected bursts of energy cannot be completely avoided, even with proper training and procedure implementation, personal protective equipment should always be worn when working with electrical equipment. Although gloves, helmets with faceshields, clothing, and harnesses can't prevent an arc flash from occurring, they can minimize the harmful physical effects of an explosion.
Using Flash-Rated Harnesses
Not all PPE is equally protective. When selecting the best personal protective equipment, utility workers should refer back to their initial assessment to determine what level of personal protective equipment is necessary.
The NFPA 70E guidelines identify how to assess the potential hazard of arc flash and necessary personal protective clothing and the safety measures to be taken when completing routine operations with energized parts ranging from 240 volts to 600 volts and higher. The standard specifies the correct gloves, helmets, and faceshields to wear when working with electrical equipment. It is important to remember that if it's not covered, it's not protected, because many technicians are often tempted to toss their faceshields aside or wear just a hood or gloves when performing routine tasks. Not only is this not compliant; it can result in considerable injuries.
NFPA 70E also requires that every piece of arc flash-rated equipment states on the label its arc flash rating. This implies the manufacturer has performed the necessary tests on the fabric and determined its level of arc flash protection. A manufacturer is required to conduct a minimum of 20 test samples of the product. If a piece of equipment is not identified with an arc flash label, it is not arc flash resistant.
Not identified by NFPA 70E, however, is one of the most important pieces of PPE for utility workers who work at height: the full-body harness. Personal protective clothing will do a utility worker little good if exposed to arc flash when working at heights and using a harness that is not arc flash rated. This is because the harness may catch fire and/or burn through, causing a worker who may have been protected from most of the damaging effects of the flash to fall.
The ASTM F887-04 Arc Flash Standard should be referenced for these situations because it specifically calls attention to safety requirements for personal climbing equipment, including full-body harnesses, when working with electrical equipment at heights. The rigorous standard specifies the acceptance testing of climbers, the effectiveness of body belts and positioning straps, and specific harnesses to be worn by workers when climbing poles, trees, towers, and other structures. ASTM F887-04 outlines strict performance criteria every harness must meet to protect employees working at height and being exposed to momentary electric arcs and flames.
Full-body harnesses should meet all criteria outlined in the Arc Flash Standard, including the Electric Arc Performance criteria, which require that the harness not melt or drip and have an after-flame life of less than five seconds after it is exposed to an electric arc. Harnesses also should meet guidelines set by ANSI Z359.1, which requires harnesses to be drop tested to check their integrity after exposure to an electric arc.
Even if a full-body harness meets all of the standards for arc flash protection, it will do little good if not worn by employees. To encourage compliance, harnesses should be designed not only for reliability, but also for the long hours and harsh conditions utility workers face. Look for harnesses with padding along the shoulders, hips, and legs to help workers remain comfortable throughout the duration of their tasks. The padding should be made from material that is flame resistant. Additional features that make a harness ideal for utility workers include dorsal web loops for no metal connections, quick connect buckles for fast and easy donning, rescue loops for bucket-truck and high-angle rescue, leather insulators under fasteners to reduce static energy transfer, and PVC coated hardware to reduce static buildup.
Full-body harnesses also should be worn when working with high-voltage systems in confined spaces. Paired with tripods and davit arms, this can be an effective way to protect against arc flash and falls, also providing a means for rescue when work is being done with electrical systems in confined spaces.
The job of working with electricity is one of the most dangerous in the nation. However, by implementing an effective training program, correctly identifying arc flash hazards, and wearing the correct level of arc flash protective gear, injuries and hefty fines can be avoided. Electricians and utility workers who work at height can also rest assured they will be safe when working with electrical equipment by using fall protection equipment, including a full-body harness that is arc flash rated.
This article appears in the July 2005 issue of Occupational Health & Safety.
This article originally appeared in the July 2005 issue of Occupational Health & Safety.