Description of the Accident
This accident occurred in the electrical room in the basement of a building when the inspection and cleaning work of transformers was being carried out by a building maintenance company under stoppage of electric power supply throughout the entire building. On the day of the accident, power supply to the entire building was planned to be off from 8:00 AM to 9:00 PM to enable five technicians to carry out transformer inspection, various measurements, and cleaning work.In addition, another company was scheduled to carry out work to replace high-voltage cables from 7:30 AM to 5:00 PM.The power supply was stopped at 6:30 AM, and four technicians (in two separate groups) spent the morning carrying out insulation checks on the distribution boards and lighting fixtures at each floor. A supervisor had attended to the high-voltage cable replacement work performed by the other company.In the afternoon, the company carried out tests on the transformer insulation oil and cable voltage resistance, and the power supply was started just before 3:00 PM. After resuming power supply, one group of workers started preparations to test the protective relays. The victim opened the door of a high-voltage incoming panel, grasped the frame of the panel case by his naked left hand and used his right hand to take out a PT fuse that had to be removed for the test. As the PT fuse was hot, the victim gasped Danger !Eand suddenly fell to the floor. He died about one hour later.
1. In spite of the fact that high-voltage current was passing from an isolator to the PT fuse and the instrument transformer, the victim tried to pull out the PT fuse without confirming whether the equipment was live or not.
2. It was found that the work plan prepared by the building maintenance company for which the victim was working was not consistent with that of the other company carrying out the cable replacement work with regard to the temporary power supply for a particular test during the total stoppage.
3. Although the cable replacement work had progressed more quickly than planned, the two companies had not readjusted their respective schedules.