Mine Safety and Health Administration
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U.S. Department of Labor Mine Safety and Health Administration Protecting Miners' Safety and Health Since 1978 |
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Jump to Overview MAI-2007-33
DEPARTMENT OF LABOR MINE SAFETY & HEALTH ADMINISTRATION Metal and Nonmetal Mine Safety and Health REPORT OF INVESTIGATION Surface Metal Mine (Copper) Fatal Electrical Accident September 14, 2007 Aker Kvaerner Industrial Constructors, Inc. Contractor ID No. 1PL at Freeport-McMoRan Safford Inc. Freeport-McMoRan Safford Inc. Safford, Graham County, Arizona Mine ID No. 02-03131 Investigator James E. Eubanks Mine Safety and Health Inspector Originating Office Mine Safety and Health Administration Rocky Mountain District P.O. Box 25367, DFC Denver, CO 80225-0367 Richard Laufenberg, District Manager OVERVIEW
Gilbert C. Guerra, contractor assistant electrical superintendent, age 46, was seriously injured on September 14, 2007, when a ground fault occurred in the 5.2 motor control center (MCC). He was troubleshooting an electrical problem in the 5.2 MCC when he contacted an energized fuse and the switch gear handle, resulting in a ground fault condition and arc flash. Guerra was hospitalized and died as a result of his injuries on July 7, 2008. The accident occurred because management policies and controls were inadequate and failed to ensure that the electrical circuit was locked out, tagged, and tested before work was performed on the circuit. GENERAL INFORMATION
Freeport-McMoRan Safford Inc., an open pit copper mine, owned and operated by Freeport-McMoRan Safford Inc., was located in Safford, Graham County, Arizona. The principal operating official was Ruben D. Griffin, general manager. The new mine was non-producing and employed 350 employees working two-12 hour shifts, seven days a week. Aker Kvaerner Industrial Constructors, Inc., located in Tucson, Arizona, was contracted by Freeport-McMoRan Safford Inc., to construct facilities at the mine. The principal operating official was John Berentis, senior resident construction manager. Aker Kvaerner Industrial Constructors, Inc., employed 850 employees at the mine. Construction began in July 2006. The last regular inspection of this operation was completed on November 14, 2006. DESCRIPTION OF ACCIDENT
On September 14, 2007, Gilbert C. Guerra (victim) started work at 5:30 a.m., his normal starting time. He went to the MCC to finish installing new electrical equipment for start-up. About 12:00 p.m., Fernando Madrid, electrical foreman, attempted to energize a switchgear inside the MCC. The circuit would not energize so Madrid asked Guerra to help troubleshoot the problem. Guerra discovered that there was no current going to the 120-volt controller. The controller was used to monitor ground faults, phase-to-phase voltage, and provide other equipment performance information. The controller also allowed the switchgear to be energized if no faults were found. Guerra and Madrid went to the 120/220 AC volt breaker panel and closed the breaker supplying power to the controller. Guerra and Madrid went back to the switchgear. Guerra looked through the switch gear window that provided visual observation of the main fuses. He noticed the flags, located inside the switch gear, were not coming down on top of the fuses to provide control power, indicating a flag tab linkage problem. Guerra attempted to lower the flags by moving the switch handle back and forth. The flags still would not come down so he placed the handle down in the open position and opened the panel door. With the door open, he pushed the mechanical interlock on the switch gear handle down and closed the handle energizing the fuses. Guerra then reached inside the energized switchgear to adjust the flag linkage. Guerra's bare left hand contacted the energized left fuse. At the same time, his bare right hand was holding the main handle and he received a phase to ground shock. Madrid saw Guerra fall forward into the switchgear. Madrid hit the trip button on the controller, called for help, and told everyone in the area to stay back until the power was de-energized. Madrid went to the MCC and verified the power was off. Matthew Wheeler, safety representative, and Michele Herod, electrician, moved Guerra away from the switchgear. Cardio-pulmonary resuscitation (CPR) was administered. Guerra was transported to a local hospital and then transferred to another hospital for advanced treatment. Guerra never recovered from his injuries and died on July 7, 2008. Death was attributed to complications due to electrical shock. INVESTIGATION OF THE ACCIDENT
MSHA was notified of the accident on September 14, 2007, at 1:00 p.m., by a telephone call from Stacey Kramer, safety manager for Freeport-McMoRan Safford Inc., to David Brown, supervisory mine safety and health inspector. An investigation began the same day. An order was issued pursuant to Section 103(k) of the Mine Act to ensure the safety of the miners. MSHA's investigator traveled to the mine, conducted a physical inspection of the accident site, interviewed employees, and reviewed conditions and work procedures relevant to the accident. MSHA conducted the investigation with the assistance of mine and contractor management and employees. DISCUSSION
Location of the Accident The accident occurred at the switchgear located in the new 5.2 MCC building near the secondary crusher. Electrical Equipment Electrical power was provided by a sub-station which reduced the voltage from 69,000 to 4,160. Power was conducted to the 5.1 MCC and then to the 5.2 MCC switchgear room into the Cutler Hammer 4160 volt, type 50 VCP-W 350 transformer. The electrical power was distributed to various pieces of equipment. The switchgear equipment involved in the accident was 4160 volts, 3 phase, dual 450 ampere fuses each rated at 5.5 Max KV that provided power to a 2500 KVA transformer. Weather Conditions The weather at the time of the accident was clear with a temperature of approximately 93 degrees Fahrenheit and calm winds. Weather was not considered to be a factor in the accident. Training and Experience Gilbert C. Guerra, victim, had approximately 20 years electrical work experience that included 15 years mining experience. Guerra had received training in accordance with 30 CFR; however, his annual refresher training was not current. A non-contributory citation was issued. Fernando Madrid had 17 years mining experience and 7 years electrical work experience. He had received training in accordance with 30 CFR, Part 48. ROOT CAUSE ANALYSIS
A root cause analysis was conducted and the following root cause was identified: Root Cause: Management policies and controls were inadequate and failed to ensure that the electrical circuit was de-energized, locked out, tagged, and tested before work was performed on the circuit. Corrective Action: Management should establish policies and controls to ensure that electrical circuits are de-energized, locked out, and tagged when work is performed on electrical circuits and equipment. CONCLUSION
The accident occurred because management policies and controls were inadequate and failed to ensure that the electrical circuit was locked out, tagged, and tested before work was performed on the circuit. ENFORCEMENT ACTIONS
Order No. 6417027 was issued on September 14, 2007, under provisions of Section 103(k) of the Mine Act:
Citation No. 6330837 was issued on September 19, 2007, under provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.12017:
Related Fatal Alert Bulletin: APPENDIX A
Persons Participating in the Investigation Freeport-McMoRan Safford Inc.
Patrick Bryce ………..senior safety representative Jeffrey Moore ………..safety representative
Rory Wilson……………safety
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