UNITED STATES
DEPARTMENT OF LABOR

At 4:15 a.m. on November 20, 2018, Employees #1, #2, #3, and #4, electrical line workers employed by an electrical contractor specializing in high voltage lines , were working at an underground electrical vault. Employees #1, #2, and #3 wer e working inside the vault, and Employee #4 was outside the vault. They were co mpleting the final phase of a Voltek Vault replacement that included changing ou t dead break elbows with load break elbows and replacing 3-way junctions with 4- way junctions along one of two 12-kilovolt circuits, the circuit on the vault's south side that was de-energized and grounded. Employee #1 was working on the north side of the vault, racking and zip-tying energized high voltage electric c ables, when an arc flash occurred. All four employees were injured in the flash . Employees #3 and #4 were transported to one hospital, where they were treated and released. Employees #1 and #2 were transported to another hospital, where Employee #2 was treated and released. Employee #1, who was closest to the origi n of the flash, was critically injured. Employee #1 was transferred to a burn c enter, where he was hospitalized for several weeks for treatment of second and t hird degree burns to his face and hands.