28-Year-Old Electronic Technician Dies from Electrical Burns in Georgia
The National Institute for Occupational Safety and Health (NIOSH), Division of Safety Research (DSR) is currently conducting the Fatal Accident Circumstances and Epidemiology (FACE) Project, which is focusing primarily upon selected electrical-related and confined space-related fatalities. The purpose of the FACE program is to identify and rank factors that influence the risk of fatal injuries for selected employees.
On August 18, 1986, a 28-year-old electronic technician died from electrical and thermal burns resulting from a flashover explosion in a 20 kV switch compartment.
Officials of the Georgia Department of Human Resources notified DSR concerning this fatality and requested technical assistance. This case has been included in the FACE Project. On March 4, 1987, the DSR research team coordinator conducted a site visit, collected incident data, interviewed a comparison worker and a surrogate for the victim, and discussed the incident with employer representatives.
Overview of Employer's Safety Program:
The employer is a large municipal transportation company which employed 3000 workers at the time of the incident. The company has an extensive safety program with a full-time safety manager and a safety board made up of representatives from each of the company's operating divisions. Safety committees have been established in each division and they conduct monthly safety discussions. Classroom safety training is provided to employees. The victim (who worked for the company less than one year) received 41.5 hours of Maintenance-of-Way Electronic Technician Training. This training addressed the theory of operation for traction power substations and gap breakers and included safety considerations.
Synopsis of Events:
On August 18, 1986, a team of five technicians was performing preventative maintenance on the AC-switch gear in a rail car maintenance shop. The lead technician placed the equipment in a maintenance mode by opening the primary switch (20 kV interrupter switch) to the power company which disconnected power to the AC-switch gear. The team members then simultaneously performed maintenance on various equipment. An electronic technician (the victim) was assigned the task of cleaning the lower compartment of the primary switch. The switch consists of a cabinet containing two compartments, each with its own door. The upper compartment contains three knife switches used to disengage the incoming power. The knife switches are gang operated by a lever mounted on the upper compartment. The lower compartment (the only area that should have been cleaned) contains circuitry for transferring power to other areas of the maintenance shop. This compartment is de-energized when the three knife switches are opened. The victim was working alone at the time of the incident.
Apparently, after opening the three switches in the upper compartment, the victim proceeded to clean the upper compartment area by spraying cleaning fluid from an aerosol spray can onto the circuitry. When the aerosol spray contacted the line side of the switch it provided a conductive plasma for the electric current. The current passed through the spray and the victim's right hand, across his chest, and exited from his left upper arm which was apparently in contact with the center switch blade. This is supported by evidence of darkening of his right thumb, a melted spray can finger actuator, and an exit wound on the inside of his left upper am. Particles removed from one open switch blade were identified as human skin by a testing laboratory. At the time of the incident, the electric current, which exceeded 3,000 amperes of phase current and 1200 amperes of neutral current as registered on power company equipment prior to the breakers tripping, caused a flash of light and loud explosion. The other technicians found the victim leaning into the upper switch compartment with his clothes on fire.
One technician used a fire extinguisher to extinguish the fire on the victim. Another technician used the plastic hose of a vacuum cleaner to pull the victim from the switch compartment. The emergency medical service (EMS) personnel responded within 5 minutes and treated the victim at the scene. The victim was transported to a nearby hospital where he died 24 hours later.
Cause of Death:
Cause of death was listed as sequela of electrical burns.
Recommendation #1: Maintenance should not be performed on energized equipment unless adequate personal protective equipment and devices are used.
Discussion: In this incident, the victim was performing inspection and cleaning maintenance on an open electrical switch which had the line side energized at 20,000 volts. Maintenance work should not be performed on high voltage equipment unless it is personally verified as de-energized and grounded. This recommendation is presently being followed by the company.
Recommendation #2: The compartment door to the primary disconnect for the power company feeder lines should be secured against unauthorized entry.
Discussion: The upper compartment door of the interrupter switch was open. Even though the victim should not have been cleaning compartments in the upper area, it was readily accessible. Securing this door would eliminate inadvertent access.
Recommendation #3: A check list should be followed to verify de-energization prior to maintenance being performed on the high voltage equipment.
Discussion: A check list should be developed that identifies the steps to be taken prior to maintenance being performed on the equipment. This verification will help eliminate maintenance being performed on energized equipment such as happened in this incident. This recommendation is presently being followed by the company.
Recommendation #4: No aerosol spray cans should be permitted to be in any high voltage rooms, such as traction power substations, gap breaker substations, auxiliary power substations, etc.
Discussion: The aerosol spray from the spray can initiated an electrical arc in the switch compartment. This recommendation is presently being followed by the company.
Recommendation #5: Existing company safety rules should be re-emphasized through training of workers in the performance of their assigned duties and the associated hazards.
Discussion: The victim violated two company safety rules. One rule stated that "when performing maintenance on equipment of 2500 or more volts, the equipment should be de-energized and grounded and work should be performed between grounds." Since the victim was working inside the primary interrupter switch compartment, he was not working between grounds.
The second rule stated "for equipment normally energized between 2500 and 50,000 volts, a distance of 3 feet should be maintained when working about the equipment. The victim was within this minimum distance requirement when he was working inside the primary interrupter switch compartment.
These rules and others will be re-emphasized by the company during foremen monthly meetings and the Safety Rule of the Day/Week Program.