Abstract: An electrical contractor dispatched an electrician and an apprentice to a town center mall to repair a defective 200-ampere fusible disconnect in a low-voltage main distribution switchboard. In preparation, the employees deenergized a 200-ampere electric power and lighting panelboard located on the second level of the mall. The panelboard was fed by the defective disconnect, which had an open pole. Next, the electrician (Employee #1) opened the disconnect switch, disconnected the load-side 3/0 AWG conductors, and reconnected then to a 400-ampere disconnect in an adjacent section of the switchgear. The electrician discovered that the A-phase internal bus hardware of the defective 200-ampere switch, including the fuse holder, was discolored from long-term overheating. This was similar to a problem he had encountered less than a month ago at another 200-ampered fusible disconnect within the same low-voltage switchboard. The problem with that disconnect, which was directly above the disconnect on which he was working that day, was also on the A-phase. Upon completion of these tasks, the electrician closed only the 400-ampere disconnect and called his employer to explain what he had found. The employer (Employee #3) and the mechanical superintendent of the mall (Employee #2) met the electrician at the switchboard. After explaining to them his findings and making a recommendation to replace the defective switches or to consider upgrading the entire service entrance switchgear, the electrician closed the door to the switch he had deactivated that day. As he was closing the door of the other defective switch, an electrical fault occurred. The ensuing electric arc burned the two employees and the employer and knocked them to the floor. They were able to crawl out of the room. The two employees were hospitalized for their injuries.