Electric Arc Hazards and Clothing
2015-05-13 14:52 | writer: admin
The line worker was out viewing a repair job at a northern US utility. The presumption was that a single unit in a three-phase transformer bank had been struck by lightning during a storm. One of the three transformers had been replaced but the secondary line was still not energized. The crew was replacing the second transformer. And the line worker was standing below the scene watching the progress of the work when the conductor apparently broke at the point where the lightning struck and fell. It landed away from his feet but created an electric arc as it fell apart. The radiated heat from the arc hit his arc and flame resistant shirt and caused little damage to his upper torso but it ignited his denim jeans and burned them completely off of his body except for a bit of denim jean fabric underneath his leather belt.
He had first and second degree burns on the front of his legs but mostly third degree burns on the back of his legs and hips. The arc may have blown the front of his jeans off quickly so that the front of his legs were not as severely burned by the fire which swept over his lower torso as the heavy jean material continued to burn. Wally Benhke, retired DuPont scientist, and one of the developers of the copper calorimeter currently used in burn prediction, once told us something that came home in this accident: “Heavy cotton is good until it ignites, and the ignition energy is almost directly proportional to the weight of the cotton material, but once the heavy cotton ignites you just have more fuel to burn on the body.” The line worker would have been much better protected with a pair of an arc and flame resistant jeans that he could have selected in the company’s clothing allowance program.
Clothing allowance programs, purchase programs, rental programs and other creative solutions to getting the right clothing on the backs (and fronts) of workers are becoming more and more important in the utility industry. Hazard assessment is moving from art to science and software programs and now “turn key services” are making it easier to MATCH the hazard and the task in order to provide for worker protection. However, new concerns continue to arise as we move forward toward the “right stuff ”.