Preparations against arc flash accidents make all the difference.
Preparations against arc flash accidents make all the difference.
By Paul Hull
Just this morning, my neighbor-probably the best electrician in town-gave me a ride downtown and showed me, in his workshop, the effects of an arc flash. Fortunately, the effects were minimal, and the worker closest had little injury. The metal and wires were twisted, melted and ruined. It was caused when a technician at a body shop suspected something was wrong with equipment so, without turning off the electricity, he swung a handle and.... FLASH!. He was lucky to have escaped with a great deal of embarrassment-and some fear. There seem to have been fewer arc flash accidents for utility companies, and that is proof awareness of the dangers and steps to avoid them has been rewarded. Well done, utilities.
If there is still anybody who doubts the benefits of good training, and workers taking that training seriously, the improved results in arc flash incidents should be convincing. An arc flash can reach as high as 35,000 volts. As my friend told me this morning, it happens much more quickly than any human reaction can match. The main protection, then, is training, and knowing what not to do-and never doing it. With an arc flash such, there is seldom a second chance. If the worker escapes with injuries, they will be painful and costly; unfortunately, death is more likely.
About a year ago there was an arc flash accident where several utility workers were injured. One bystander said he could see smoke coming from one of the injured victims. Nobody was killed. There was no information given about the causes of the arc flash, and the utility said it was the first such incident they could remember in at least the past five years. One spokesperson said the utility spends "an inordinate amount of time safety-training with our staff." Inordinate means excessive or immoderate; I don't think that's what the spokesperson meant because that would nullify the value of good training.
Sources and Remedies
The National Fire Protection Association (NFPA) 70E: Standard for Electrical Safety in the Workplace is probably the document most read concerning electrical safety. The Occupational Safety and Health Administration (OSHA) reinforces the principles laid down in that document and emphasizes that safety-related work practices should be used to prevent electric shock or other injuries that follow direct or indirect electrical contacts. OSHA can enforce safety practices. NFPA 70E-2000 is often considered the standard "right way to do it" guide. Among the actions companies should take to be in compliance with federal regulations are: a safety program with defined responsibilities, personal protective equipment (PPE) for workers, training, tools for safe work, and calculations for the degree of electrical safety hazard. Much of this applies to commercial and industrial plants as well as to utilities. Petrochemical companies, with their plethora of expensive equipment, have been prominent in their efforts to avoid electrical hazards such as arc flashes. The best way to prevent injuries to workers with electrical hazards is to de-energize equipment before beginning to work. My electrician friend told me the arc flash that took place this morning would not have occurred if the company had a lineman de-energize the equipment involved. At the time, that probably seemed like too much trouble and it might slow down the day's work.
Not only should approved warning labels be attached at appropriate places where arc flash could threaten-they should also be readable and read by employees. Much of the success in beating the deadly menaces of arc flashes will be achieved by everybody at the site doing what they have been trained to do and not thinking that, just this once, it's not worth bothering with. There are several PPE brand names and you are probably familiar with them. Check with back copies of Utility Products to see advertisements and articles that may help you make decisions about specific brands. Personal protective equipment covers clothing and accessories for all types of hazard, and it should be emphasized that protection against arc flash requires specific rather than generic products.
One word you will come across when hearing about arc flash dangers is boundary. If you think of the arc flash as the center of an archery target or bullseye, there are four boundaries often cited. The closest to the center is the Prohibited Approach Boundary; the next one out is the Restricted Approach Boundary; the third one out is the Limited Approach Boundary; and finally, the Flash Protection Boundary. The last one is where a worker would be exposed to a "curable second degree burn." The heat generated by the flash results in burns. At the Limited Approach Boundary there is a shock hazard, too, and that risk is greater at the closer, Restricted Approach, distance. The Prohibited Approach Boundary marks the position where the worker might as well have contact with the live part that could cause the arc flash. The actual boundaries for a particular piece of equipment will be decided (not guessed at) where the piece of equipment that operates at 50 volts or more has not been put into a de-energized state. After that evaluation, you can determine what levels and types of PPE should be worn. The correct label also must be placed to show current and future workers of the dangers at that particular site. Let's emphasize that the most effective way to eliminate the dangers of arc flash is simple-de-energize the equipment involved.
Some labels will only tell you there is an arc flash hazard, the suitable PPE is required, a warning that failure to follow the prescribed steps could result in injury or death, and a reference to NFPA 70E. A better, more detailed label will tell you the flash hazard boundary; the level of PPE to be worn; the flash hazard at, for example, 18 inches; the shock hazard if the cover is removed; and the distances for limited, restricted and prohibited approach. Most important is that the worker reads and understands the label.
Protecting the Workers on the Line
Linemen (or women) may work several feet underground and high overhead. Both situations are possible sites for arc flashes, and utilities have done a good job protecting their employees. Protective gear is most useful but the best preparation is training-and remembering that training. What have utilities done? Some have changed practices that were believed to be sacrosanct for decades (which could be restating the distance a worker should keep between him and the arc flash potential, possibly up from four to six feet), and some have provided flame-resistant clothing to all field workers. It's worth the effort to research every product you buy, and personal protection equipment is high on the list of products that must be as good as they claim. Do you buy protective clothing, for example, that is flame-resistant or chemically induced flame-retardant? One utility discovered that flame-resistant material (with the resistance inherent in the materials of the clothing) could be preferable for a practical reason. The protection level did not go down every time the clothing was washed. Of similar importance is to have your employees try wearing suggested protective clothing. Which brand or type is more comfortable? Which does not interfere with the efficiency of the worker?
Protective clothing is not inexpensive, and the seller should be willing to listen to your needs and adjust to them. Are all your workers the same size? If they aren't, why should somebody expect you to buy clothing that is all the same size? If you buy clothing for yourself in your private life, do you walk into the store, see a nice-colored article and buy it-even if you wear a size Large and the clothing is Small or 2XL? Of equal importance is the cleaning of the protective clothing. Much of it doesn't hold up well to high temperature drying when laundered, so the wearers or the utility (whoever does the cleaning) should be warned about best practices and worst practices. What seemed like a small point when it was first mentioned to me, but became an obvious danger when it was explained, was the repair of protective clothing. After the effort to put flame-resistant, protective materials into clothes for linemen, it would be dangerous to repair rips and tears with nylon thread and patches. It would be an easy error to make, so warn your workers against such repair work.
Of all the dangers in industrial work, arc flashes could be the most dangerous and life-threatening. Well done, those of you who have carefully trained your workers to avoid them. Well done, those of you who have provided protective materials and tools to your employees. It would be a good year when we can lower the number of injuries and deaths from arc flashes yet again.