UNITED STATES
DEPARTMENT OF LABOR

Abstract: The chief operating engineer for an office building was investigating the cause of a lighting failure on the seventh floor of the building. He found two tripped circuit breakers in a 277-volt panelboard. He closed the two circuit breakers. A second complaint about lights out on the seventh floor led the employee to investigate further. He removed the front cover of the panelboard and found that one phase bus was not energized. He traced this phase back to its source, a 480/277-volt, 150-ampere, three-phase disconnect switch. He used test equipment to locate a blown fuse on one phase. Using a nonmetallic fuse puller, he began to pull the open fuse while it remained energized. He did not deenergize the fuse to avoid disrupting power while he retrieved a replacement on another floor. The top of the fuse came out easily, but the bottom, or line side, of the fuse was stuck. He pulled on the fuse pullers with both hands. The fuse broke loose and caused an electrical fault. The ensuing electric arc burned the employee. He was hospitalized for 17 days for second- and third-degree burns to his hands, arms, face, and chest.