UNITED STATES
DEPARTMENT OF LABOR

Inspection Detail

Inspection: 317892891 - Day And Zimmermann Incorporated

Inspection Information - Office: South Carolina Priv

Investigation Summary

Employees of an electrical contractor were at a power generation facility, conducting voltage testing on a 4160/480-volt station service transformer, which was an upgrade replacing an old transformer. The transformer, which was 2 meters tall and 3.7 meters long, with four 0.9-meter-wide sections, did not have any exposed live parts. Each section had seven vent openings, which were about 38 millimeters wide and 610 millimeters long, at the top and bottom of each panel. The Plant Operator closed the circuit breaker for the transformer in the breaker room, energizing the transformer. The transformer had five positions on the tap changer, and the employees were moving from lower voltage to higher voltage, taking voltage readings. Three employees did a brief walk around to look at what was needed to do the work. The tap changer was in position three, and the bus 3 meter read 4445 volts instead of the expected reading of 4160 volts. The work order stated that the transformer had to be energized to change the taps. The employees had to release the locking pin on the tap to turn the handle. At each position of the tap changer, Employee #2 released the locking pin, and Employee #1 turned the handle. When Employee #1 turned the handle slowly, they saw a small electric arc. They stopped and took a voltage reading. The employees were instructed move quicker and move to position one. As the employees moved the tap from position four to five, they noticed another electric arc. After the arc, there was smoke and an electrical fault. Employee #2 pushed Employee #3 out of the way, and Employee #1 yelled that his clothing had ignited. Employees were wearing hard hats, safety glasses, leather gloves, and regular street clothes. Employee #1 received second-degree burns to his left arm, shoulder, right collar bone, and both butt cheeks. He was hospitalized for his injuries. Employees #2 and #3 received first-degree burns.

Keywords:burn, clothing, electric arc, electrical, electrician, e ptd, substation, elec utility work, electrical fault, transformer