New Jersey Case Report: 91NJ006 (formerly NJ9104)
Factory Worker Electrocuted After Contacting 480 Volts While Attempting to Reset a Relay in an Electrical Cabinet
DATE: July 23, 1991
On April 8, 1991, a 50-year-old factory worker was fatally electrocuted after falling onto the exposed conductors in an energized 480 volt electrical cabinet. The incident occurred at a plastic bottle manufacturing plant after an automated pallet conveyor system stopped during a power overload. Attempting to reset the system, the worker opened an electrical cabinet and reached in to reset an opened relay. He was electrocuted when he apparently fell and contacted the energized terminals of the relays and breakers within the cabinet. NJDOH FACE investigators concluded that, in order to prevent similar incidents in the future, the following safety guidelines should be followed:
On April 8, 1991, NJDOH FACE personnel were notified by the county medical examiner of a fatal work-related electrocution that occurred earlier that morning. On the same day, a FACE investigator visited the site to interview the employer and photograph the scene. A second site visit was conducted May 20, 1991 to further examine the electrical cabinet. Other information was derived from witness statements, the OSHA compliance officer, police report, and medical examiner's report.
The employer is a manufacturer of plastic bottles that employs about 200 workers in a three shift operation. The plant has been in operation since 1977 but has been run by the current owner for the past 3 years. The company employs a safety officer and has a written lock-out tag-out procedure. The deceased was a 50-year-old male who had been working at the plant for over 7 years. For the past 6 years he was employed as a utility operator whose responsibilities included operating the automated pallet transfer system.
On the morning of the incident, the victim was engaged in operating the automated pallet transfer system with a co-worker. In this operation, pallets of finished plastic bottles roll down to the end of a conveyor line. An automated, rail-mounted "transfer car" then rolls to the end of the conveyor and the pallet is rolled onto it. The car then moves on to the next conveyor line and transfers the pallet onto it. The pallets are then moved to the warehouse.
Between 2:30 and 3:00 a.m., the transfer car jammed and tripped the motor overload relay. This relay, located in a electrical cabinet near the conveyors, opens during a power overload and stops the transfer car. The victim told his co-worker that he would take care of the problem, and the co-worker left the area. Although he was not trained or authorized in the procedure, the victim apparently had watched trained personnel reset the relay. The victim went to the transfer system control cabinet, which is a large electrical cabinet with three doors. He opened the left hand door of the cabinet, apparently to reach towards the center of the cabinet to reset the motor overload relay.
At this time the co-worker returned to the area and saw the victim fall into the cabinet and begin to shake. He had become wedged against the breakers and door support, with the current passing from the breaker into his head and exiting through his chest to the grounded cabinet. The co-worker immediately ran and shouted for help, attracting a second employee who shut down the power to the cabinet. While the victim was being freed from the cabinet, a third employee called for an ambulance. The third employee then began CPR on the victim and continued until the police arrived and took over. The ambulance arrived soon after and transported the victim to the emergency room where he was later declared dead.
Our investigation found that the transfer system control cabinet is equipped with a mechanical interlock system that prevents the left and center doors from being opened unless the right door is opened first. The right door is equipped with a lock that can be opened using a screwdriver as a key. Because the victim was approaching the breaker from the left instead of the center door (where the breaker was located), it appears that the left door had been left open while the others were sealed with the interlock system. The lack of burns on his hands suggest that he did not contact the current until after he fell into the cabinet. It was not determined what actually caused him to fall.
CAUSE OF DEATH
The cause of death was attributed to electrocution. The medical examiner's report stated that there were electrical burns on the face and right flank of the victim's body. No burns were noted on his hands.
RECOMMENDATIONS AND DISCUSSION
Recommendation #1: All electrical cabinets should be securely locked and equipped with a safety interlock system that de-energizes the contents of the cabinet when the doors are opened.
Discussion: Although the electrical cabinet in this case was equipped with a mechanical interlock, the energized breakers could be accessed if a door was left ajar or if the lock was opened with a screwdriver. We recommend that each cabinet door should be securely and independently locked to prevent unauthorized entry. In addition, a safety interlock system should be provided which de-energizes the cabinet whenever a door is opened or left ajar. This is recommended for all electrical cabinets.
Recommendation #2: Develop, implement, and enforce a comprehensive safety program which includes worker training in avoiding hazards electrical and other safety hazards.
Discussion: Although the worker was not trained or authorized in resetting the relay, he apparently felt that there was little or no risk in doing so. It is recommended that a comprehensive safety program should be implemented that includes training in identifying and avoiding electrical hazards. Training should be related to the employee's duties, with general factory workers receiving awareness training while maintenance workers receive more advanced training.
Recommendation #3: All electrical cabinets should be posted with signs identifying them as containing high voltage.
Discussion: All electrical cabinets and systems that may be accessible to employees should be posted to identify those areas as dangerous and containing high voltage. Posting, in conjunction with a safety training program, will emphasize the electrical hazard to the employee.
FATAL ACCIDENT CIRCUMSTANCES AND EPIDEMIOLOGY (FACE) PROJECT
Staff members of the FACE project of the New Jersey Department of Health, Occupational Health Service, perform FACE investigations when there is a work-related fatal fall or electrocution reported. The goal of these investigations is to prevent fatal work injuries in the future by studying: the working environment, the worker, the task the worker was performing, the tools the worker was using, the energy exchange resulting in fatal injury, and the role of management in controlling how these factors interact.
To contact New Jersey State FACE program personnel regarding State-based FACE reports, please use information listed on the Contact Sheet on the NIOSH FACE web site. Please contact In-house FACE program personnel regarding In-house FACE reports and to gain assistance when State-FACE program personnel cannot be reached.