Abstract: A three-person power line crew was replacing one of a set of three voltage regulators at a substation. The crew consisted of a substation supervisor and two substation electricians. The crew's maintenance supervisor stopped by to observe the operation. The crew obtained switching orders to deenergize the three regulators, which were located on the east side of the substation. The bad regulator was located on the south end of the regulator bank. The crew bypassed the load on the regulators and deenergized them. The crew then replaced the malfunctioning regulator with an Allis-Chalmers regulator (Serial No. 3-3740-00228-9). After the crew visually determined that the controls were in the neutral position as required by the manufacturer, the two electricians took a break. One of them was at the back of the maintenance truck, which was located about 4.3 meters south-southwest of the new regulator. The other electrician was further forward. While these two employees were on break, the substation supervisor closed the bus-side contacts on the three regulators, energizing them. He then closed the load-side contacts. About 5 minutes passed since the supervisor energized the south regulator, but none of the regulators was under full load, as the bypasses were shunting load around the regulators. When the supervisor opened the bypass switch for the new regulator and placed it under load, the regulator failed. The internal pressure in the regulator forced open its lid directly in line with the first electrician, who was sitting on the back of the truck. A large quantity of burning oil from the regulator struck him. The oil also struck the other electrician and the maintenance supervisor, but they were apparently not injured. The second electrician and the substation supervisor extinguished the flames on the injured employee, while the maintenance supervisor summoned emergency medical services with his radio. The injured employee was transported to a local hospital and transferred to a burn center, where he died of complications resulting from second- and third-degree burns over 80 percent of his body.

Abstract: A power line worker was performing a switching operation. The employee was standing over an open underground vault located under a sidewalk. He was using a 2.4-meter-long live-line tool to close a switch on a 12-kilovolt backup circuit feeding three transformers. The switch was normally open; it was closed only to reroute power when the primary circuit was out. The normal anticipated load to be applied to the backup circuit was 15 amperes, and the 1-0 AWG cables for the backup circuit were rated at 25 kilovolts and 200 amperes. When the employee closed the switch, the cable failed. The ensuing electric arc burned the employee. He was hospitalized with first-degree burns to his face and arms and second-degree burns to the underside of his upper arms.

Abstract: Two power line workers were working on a utility pole, replacing one transformer in a bank of three. The employees replaced the defective Central Transformer Co. transformer (Serial No. 2370474314) with a new Howard Industries transformer (Serial No. 1260760597). The other two transformers in the bank were manufactured by Central Transformer Co. (Serial No. 2370474813) and McGraw-Edison (Serial No. 69VK084005). After the transformer was replaced, one of the power line workers tested the transformers for voltage and asked the customer to close the main power switch. After about 50 seconds, the McGraw-Edison transformer failed. The oil inside the transformer ignited and sprayed over the pole, the employees, and their truck, which was parked nearby. Both employees died of electric shock and burns received in the accident. (The cause of the electric shock was not noted on the original form.)

Abstract: Two journeyman high-voltage electricians were dispatched to a substation to troubleshoot a regulator that was not responding to automatic control. They had completed a low-voltage relay examination and replaced a loose Porter Brumfield relay in its socket. They then placed the controls on manual, adjusted voltage, and returned the regulator to automatic control to determine whether it was functioning correctly. The stepping device moved one step, and then the regulator failed, spewing burning insulating oil out of the overpressure vent. The hot oil burned both employees. One of them died of his injuries.

Abstract: Two power line workers were asked by their supervisor to perform a switching operation at a substation. They were given a written switching order for this task. Following the written procedure in the order, they opened a disconnect that was energized at 12 kilovolts. Apparently, the disconnect failed, causing an electrical fault. The two employees sustained second- and third-degree burns as a result of the ensuing electric arc. They were hospitalized for their injuries.

Abstract: A repair crew for an electric utility was working the night shift, repairing and switching a faulted 11-kilovolt circuit. A switch, which was located inside an underground vault that had water in it, was to be replaced. A sump pump was used to remove the water, but the crew's supervisor ordered one of the employees into the vault while the water was still 2 feet deep. As the switch was being removed, numerous parts were lost. Additionally, the replacement equipment was not of the same design as the original equipment. Apparently, as the employee was reassembling the switch, it fell into an energized position and failed. The resultant electric arc burned the employee, who was hospitalized for his injuries. (The supervisor stated that the injured employee had been adequately trained and warned of the hazardous conditions.)

Abstract: Three power line workers were opening a 13.8-kilovolt switch so that work could be performed on a power line to a transformer. After checking back to the 115-kilovolt circuit breakers on the high-voltage side of the transformer, one of the employees unlocked the operating bar for the switch and placed its handle in the open position. His two coworkers were standing behind him in single file. The employee operating the handle moved it first to its normal open position and then moved it a little more. This caused the switch to fail, creating an electrical fault. The ensuing electric arc ignited the oil in the switch, and the burning oil spewed out. The employee who opened the switch was burned on his face, neck, and hands by the hot oil and flash fire. His neck and face were lacerated by flying metal switch parts. He was hospitalized for treatment of his second-degree burns. The other two employees sustained minor burns on their faces, necks, hands, and arms. They were treated for their burns at the emergency room of a local hospital and released.

Abstract: A power line crew for an electric utility was phasing an electric generator to a power line. A nylon screw in the test stick failed, causing an electrical fault. The ensuing electric arc burned five of the employees; one of them was severely burned. Four of the five employees were hospitalized for their injuries. The crew was well trained and qualified to perform this job. The crew members were wearing proper personal protective equipment, which, in most cases, prevented more severe injury.

Abstract: Three power line workers for an electric utility were performing preliminary work on a 34-kilovolt distribution circuit that was to be replaced by a 13.2-kilovolt circuit. The employees were testing the transformer secondaries with a rotation meter to determine the phase sequence of the transformers' loads. One of the crew members (employee #2) had just connected the meter, which was rated at 600 volts, to the 2300-volt output. His two coworkers were observing the operation. The underrated meter failed, initiating a phase-to-phase electrical fault. The ensuing electric arc burned the three employees and ignited their clothing (which resulted in further burn injuries). Employees #1 and #2 sustained second- and third-degree burns. The third employee sustained second-degree burns. The employee using the meter thought that the voltage was 480 volts. His coworkers did not inform him of the actual voltage and did not recognize the hazards involved with using the underrated meter.

Abstract: A power line worker was working in a 1.2-meter by 2.4-meter electrical vault. The employee used a live-line tool to place a non-load-break elbow on an energized 7200-volt bushing. When the elbow contacted the bushing, it failed and caused a fire in the vault. The employee's clothing ignited. A second employee pulled the injured worker out of the vault and doused the burning clothing. Both employees suffered burns. The second employee was treated at a hospital and released. The first employee was hospitalized for his injuries. (The power line worker knew not to energize a load through a non-load-break elbow, but he mistakenly thought that it was safe to energize an unloaded power line through this type of connection.)

Abstract: An Allis-Chalmers transformer (Serial No. 21-114-502-424) had been installed in a new substation. While it was being tested, it failed, and the resulting explosion released burning oil onto a foreman for an electric utility crew. The foreman, who had been standing about 2.4 meters away from the transformer while the test was being conducted, was burned on his back. He died of his injuries. The transformer manufacturer inspected the transformer and found that the cause of the explosion was internal failure.

Abstract: A power plant operator was working in a high voltage switchgear room. The employee had been assigned the task of installing earthquake clips inside the metal-clad, 4160-volt switchgear. The employee opened the rear of the bus section, exposing the bus and current transformers. The employee believed the current transformers to be step-down transformers. He obtained a tester rated at 600 volts and applied it to the current transformer terminals. The tester failed, and the ensuing electric arc burned the employee, who became engulfed in flames. The employee was severely burned on his arms, torso, and face and was hospitalized for his injuries.