DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
REPORT OF INVESTIGATION
(Underground Coal Mine)
Fatal Electrical Accident
May 23, 2002
Mine No. 4
Calvary Coal Co., Inc.
Smilax, Leslie County, Kentucky
I.D. No. 15-16349
Accident Investigator
Dennis J. Cotton
Mining Engineer
Originating Office
Mine Safety and Health Administration
District 7
3837 S. U.S. Hwy 25E
Barbourville, Kentucky 40906
Joseph W. Pavlovich, District Manager
Report Release Date: March 13, 2003
OVERVIEW
On June 27, 2002, a 58-year-old electrician died from complications due to injuries received on May 23, 2002 in an electrical accident. At the time of the accident, a mine electrician with 21 years of experience, was attempting to remove a short circuit from the trailing cable of a model 21SC Joy shuttle car. The method used by the victim involved installing "jumper" wires between the trailing cable coupler of the shuttle car and its receptacle on the 1,100 KVA power center, and next energizing the cable at the circuit breaker. A subsequent electrical arc and explosion occurred at the female receptacle on the power center which resulted in the victim receiving burns to 40 - 50% of his body. Following the accident, the victim was transported to the surface and was subsequently air-lifted to the University of Kentucky Medical Center in Lexington, Kentucky. As a result of those injuries, the victim died 35 days later.
The fatal accident occurred as a direct result of altering the wiring configuration by utilizing "jumper" wires to energize the grounding conductor of the trailing cable of a shuttle car with a phase conductor in the female receptacle. The root cause of the accident centered upon unsafe work practices and inadequate electrical testing equipment.
GENERAL INFORMATION
Mine No. 4 is an underground mine, located near Smilax, Leslie County, Kentucky and is currently operated by Calvary Coal Co., Inc. The mine has three drift openings into the Hazard No. 4 seam which averages 48 inches in thickness and is mined by the room and pillar method. The mine produces coal with one working section, two shifts per day, five days per week. Maintenance and support work are performed on the third shift. The average daily production for the mine is reported at 1,400 tons. During the first quarter of the calendar year 2002, mine production was reported at 96,482 tons, and total employment was reported at 52 employees. Coal is mined utilizing a Joy Model 14CM-10 continuous mining machine and is transported from the face utilizing two Joy Model 10SC shuttle cars and one Joy 21SC shuttle car into a feeder. Coal is then transferred onto a series of belt conveyors where it is transported to the surface. The roof is supported during advance mining by installing fully grouted resin roof bolts with a Fletcher roof bolting machine equipped with an automated temporary roof support (ATRS) system. During retreat mining the roof is controlled utilizing posts installed in accordance with the approved roof control plan. Currently the mine consists of one working section, main entries, panels, and gob areas created by pillar extraction. Floyd Wells Coal & Land Company own the property currently being mined.
The principal officers of the operation are as follows:
James Napier .......... PresidentA regular health and safety inspection (AAA) by the Mine Safety and Health Administration (MSHA) had begun on April 8, 2002, and was on-going at the time of the accident. The previous AAA was completed on March 13, 2002. The Non-Fatal Days Lost (NFDL) Incident Rate (not including office workers) for this mine is 6.16 for the first quarter of 2002. The Industry NFDL rate for underground mines for the same reporting period was 7.04.
Lonnie Napier .......... Secretary
DESCRIPTION OF THE ACCIDENT
The day shift for May 23, 2002 began, as scheduled, at approximately 6:00 a.m. The production crew traveled from the surface by rail mounted personnel carrier to the 001 working section under the supervision of Kennard Morris, Section Foreman. Upon arrival on the working section, the crew assisted the third shift crew in completing a move to pull the section power center back, as the section was retreat mining.
Once production had begun, an electrical problem developed with the Model 21SC Joy Shuttle Car, serial no. ET12404, being operated by Arthur D. Sizemore. According to statements made in the interviews, the circuit breaker for the shuttle car had tripped three or four times, and had been reset by victim Don G. Campbell, at the section power center. Sizemore stated the last time the circuit breaker tripped, that it would not reset.
Repair work was begun by Campbell to find and correct a grounded phase in the No. 6 AWG trailing cable serving the shuttle car. One splice in the cable was repaired. However, the circuit breaker for the shuttle car still would not close. Campbell instructed Sizemore to observe the trailing cable. Campbell left Sizemore at the shuttle car and walked to the 1,100 KVA Kris Electric power center.
While at the power center, Campbell installed "jumper" wires between the trailing cable coupler of the shuttle car and its receptacle on the power center and subsequently energized the cable at the circuit breaker. An electrical arc and explosion occurred at the female receptacle on the power center resulting in the victim receiving severe burns to 40 - 50% of his body.
Gary Maggard, belt person, was located at the section's Stamler feeder when he reportedly saw a bright flash at the section power center. Maggard immediately responded to the situation and next called on the mine telephone for the power coming to the working section to be de-energized. Henry McQueen, Jr., belt person, was located near the No. 3 belt conveyor head drive. McQueen stated that he heard Maggard request that the power be "knocked" and immediately de-energized the power at a splitter box near the belt drive. Persons on the surface were also notified of the accident by mine telephone. Randy Roberts, General Mine Foreman, Rick Sandlin, Chief Electrician, and Larry Mitchell, Motorman, responded by immediately traveling by rail mounted personnel carrier to the working section.
Arthur Sizemore, who had been observing the trailing cable at the time of the accident, immediately traveled to the No. 6 entry where the Joy Model 14-10CM continuous mining machine was located. Sizemore informed Kennard Morris, Section Foreman, that an accident had occurred at the section's power center. Morris immediately traveled to the accident scene to assist the victim.
According to statements obtained during interviews, Campbell was both conscious and alert immediately after the accident. The intense heat from the electrical arc at the female receptacle of the shuttle car had burned parts of his clothing and had reportedly severely burned a large portion of his body.
The track mounted personnel carrier arrived on the section and Campbell was immediately transported to the surface accompanied by Rick Sandlin who is also a trained Mine Emergency Technician.
Campbell was subsequently airlifted to the University of Kentucky Medical Center in Lexington, Kentucky. At 2:20 p.m., on June 27, 2002, Campbell succumbed to the injuries received in the accident.
INVESTIGATION OF THE ACCIDENT
At approximately 8:15 a.m. on May 23, 2002, James W. Oakley, Sr., Supervisory CMS&H Inspector of MSHA's Field Office in Hazard, Kentucky was notified of the accident by Ryan Osborne, Purchasing Agent. An initial response team comprised of Oakley and Charlie Fields, CMS&H Inspector, immediately responded to the notification. Upon their arrival at the mine, a 103-k Order was issued to ensure the safety of miners until an investigation could be conducted. An Accident Investigation Team consisting of Dennis J. Cotton, Mining Engineer and Patrick A. Stanfield, CMS&H Specialist - Electrical, arrived at the mine at 12:15 p.m. to begin the investigation. Stephen B. Dubina, Electrical Engineer, from MSHA's Pittsburgh Safety and Health Technology Center, Mine Electrical Systems Division, also assisted in the on-site investigation and the testing and evaluation of the electrical components.
MSHA and the Kentucky Department of Mines and Minerals (KDMM) jointly conducted the investigation with the assistance of mine management and the miners. Formal interviews were conducted at MSHA's Hazard, Kentucky Field Office with 14 employees of Calvary Coal Co., Inc. on May 24, 2002.
During the investigation components of the Westinghouse circuit breaker involved in the accident were sent to Pittsburgh Material and Environmental Technology for analysis of their metallurgical composition.
A list of those who were present and/or participated in the investigation is included as Appendix A. None of those persons interviewed requested that their statements be kept confidential.
DISCUSSION
A review of the training records for the victim indicated that all required training in 30 CFR 48 had been completed. Campbell had received required annual refresher training for experienced miners on September 15, 2001, and had received required annual electrical training on November 03, 2001.
Interviews were conducted with mine personnel to determine the facts relating to the accident and to also gather information about electrical maintenance at the Mine No. 4. None of the persons interviewed were aware that Campbell was installing the "jumper" wires between the cable coupler of the shuttle car and its receptacle in the section power and energizing the cable at the circuit breaker in an attempt to remove the grounded phase in the shuttle car cable. This practice is known as "blowing a cable." Based on statements obtained during the interviews, this was a common and acceptable practice at the mine. Several persons, including members of mine management, stated that they had knowledge that trailing cables were intentionally short-circuited to remove grounded phase conditions.
A Hi-Pot (High Potential) Cable tester, commonly known as a "thumper" had reportedly been in use at one time at this mine to locate grounds in cables. This is a device which can be used to safely locate grounds in cables. The tester had become defective and had been removed from the mine some time prior to the accident.
The on-site investigation revealed a short circuit existed in the trailing cable of the No. 3 Joy 21SC-56BHE-1 (Serial No. ET12404) shuttle car. The trailing cable was a No. 6 AWG, Type G-GC Flat, in which the white phase lead was shorted to the green ground lead, resulting in the circuit breaker tripping. The circuit breaker protecting the shuttle car was installed in a 1,100 KVA Kris Electrical Co. power center (Serial No. 92421) with the following characteristics:
Manufacturer: Westinghouse ElectricThe subject circuit breaker was attached to a panel which contained a receptacle that was found to have been damaged by a short circuit. The handle was in the "on" position. After removing the circuit breaker from the board, the handle was operated by moving it to the "trip" position. The handle sprang back to the "on" position, despite the breaker mechanism being tripped. There was also evidence that the cover had been repainted.
Thermal rating: 225 amps
Magnetic Rating: 300 - 700 amps (set on 700 amps)
Voltage: 600 volts AC maximum
Type: KAM3225
Identification No.: 1291C26G03
Options: 120 volt AC-UV Release
Date Mfg.: 1994
Each pole was tested for continuity using a multi-meter, and all three poles indicated 0.1 ohms resistance per pole. This is indicative of the circuit breaker contacts being closed. The pole-to-pole resistance was measured using a 500V DC Megger tester. Observed readings indicated there were no short circuits internal to the circuit breaker.
The front cover of the circuit breaker was removed. Visual examination revealed that the inside of the circuit breaker was fairly clean. The internal metal parts of the breaker appeared to have been sandblasted or cleaned by some other method. The copper conductors appeared to have been sanded clean and all factory silver plating was removed. Also, there was no rust found on the cleaned steel parts.
The circuit breaker mechanism was examined. It was found in the "tripped" position. All three contacts remained closed, which indicated a welded contact. The left and right contacts proved to be free, but the center contact tip proved to be welded. The center weld was broken, and all three contact tips separated. Once the center weld was broken, the breaker and breaker handle would operate properly when opened and closed.
Further investigation of the moving and stationary contacts revealed that each of the moving poles had a different contact configuration. The left pole (left and right directions are observed as the breaker is in its normal operating position) had two contacts, a moving main and an arcing contact tip. The center pole's moving contact was found to be substantially narrower than the left or right moving contact. From these observations, it was concluded that the center pole had been replaced with a narrower moving contact sometime after the circuit breaker's original manufacture. Investigators verified the calibration for the circuit breaker, both for the thermal and magnetic settings. Published trip times for KAM breakers were taken from their time-current curves. The maximum "trip-out" time at 200% on a single pole test is approximately 11 minutes. The magnetic trip range for this trip unit is from 300 to 700 amperes. On the "HI" setting, this would translate to 700 amperes with a +/- 10% tolerance. Investigators next concluded that the circuit breaker would have tripped during an overload or short circuit condition if the center pole moving contact had not been welded to the center pole stationary contact.
The circuit breaker was disassembled, and parts of each contact were removed and sent to Pittsburgh Material & Environmental Technology, Inc. for analysis of their metallurgical composition. The circuit breaker's contact tips were analyzed using a scanning electron microscope (SEM) with an energy dispersive X-ray detector. The results of these tests indicated the composition of the center movable contact was 100% silver. Cutler-Hammer uses a combination of tungsten and silver in all of their circuit breaker contact tips. The center movable contact with 100% silver on the tip was determined to not be original equipment. Silver has a much lower melting temperature than a contact made of silver and tungsten. Under a high current condition, a purely silver-based contact tip would be more likely to weld than a tungsten-silver contact tip. The circuit breaker was found to have a contact tip welded together from previous faults on the cable.
ROOT CAUSE ANALYSIS
A root cause analysis was performed on the accident. The following causal factors and root causes were identified which the investigators believe could have averted the accident entirely:
1. Causal Factor: An attempt to remove a short circuit from the trailing cable of the Joy Model 21SC shuttle car (Serial No. ET12404) by installing "jumper" wires from the cable coupling of the shuttle car to its receptacle on the 1,100 KVA Kris Electric Mfg. Co. power center created an electrical arc at the receptacle that caused fatal burn injuries. Root Cause - This hazardous practice was known by members of mine management and accepted as a means of removing a ground in a trailing cable. The Hi-Pot (High Potential) Cable Tester which had been used previously at the mine to locate a ground in a trailing cable was reported to have malfunctioned and had earlier been removed from the mine. This device was therefore not available to the victim for use in locating the grounded phase in cables.
Corrective Action: The operator has discussed with all management and employees that the practice of intentionally short circuiting a trailing cable to remove a grounded phase is a highly dangerous practice and will not be accepted as a means to locate and remove a ground in a cable. The operator has also provided authorized employees with an operative Hi-Pot (High Potential) Cable Tester for locating grounds in trailing cables.
CONCLUSION
The fatal accident occurred as a direct result of altering the wiring configuration by utilizing "jumper" wires to energize the grounding conductor of the trailing cable of a shuttle car with a phase conductor in the female receptacle. The root cause of the accident was centered upon unsafe work practices and inadequate electrical testing equipment.
ENFORCEMENT ACTIONS - Contributing Violations
Citation No. 7479064, 104(d)(1), 30CFR75.512, S&S, High Negligence. On May 23, 2002 an electrical accident occurred on the 001 Section resulting in fatal injuries to a miner. Electrical equipment was not properly maintained to assure safe operating condition. "Jumper" wires were installed between the cable coupler for the model 21SC Joy shuttle car (Serial No. ET12404) to its female receptacle in the 1,100 KVA Kris Electric Co. power center changing the wiring configuration to energize the grounding conductor of the trailing cable for the shuttle car with a phase conductor in the female receptacle. This condition contributed to the electrical arc that caused the fatal burn injuries. This practice was known and condoned by members of management as an acceptable means of removing a ground in a trailing cable.
Order No. 7479063, 104(d)(1), 30 CFR 75.601-1, S&S, High Negligence. On May 23, 2002 an electrical accident occurred on the 001 Section resulting in fatal injuries to a miner. The instantaneous setting for Westinghouse circuit breaker (Identification No. 1291C26G03) providing short circuit protection for the No. 6 AWG trailing cable of the model 21SC Joy shuttle car (Serial No. ET12404) exceeded the maximum allowable setting. The instantaneous setting was 700 amperes, which exceeds the maximum allowable setting of 300 amperes for No. 6 AWG trailing cable.
Order No. 7479065, 104(d)(1), 30 CFR 75.509, S&S, High Negligence. On May 23, 2002 an electrical accident occurred on the 001 Section resulting in fatal injuries to a miner. The power circuit for the model 21SC Joy shuttle car (Serial No. ET12404) was not de-energized while a person was performing an unsafe electrical work practice. "Jumper" wires were installed between the cable coupler for the shuttle car and its female receptacle on the 1,100 KVA Kris Electric MFG. Co. and subsequently energizing the cable at the circuit breaker. This practice of performing unsafe work on an energized electrical circuit resulted in an electrical arc at the female receptacle causing the fatal burn injuries. This practice was known and condoned by members of management as an acceptable means of removing a ground in a trailing cable.
Order No. 7479066, 104(d)(1), 30 CFR 75.511, S&S, High Negligence. On May 23, 2002 an electrical accident occurred on the 001 Section resulting in fatal injuries to a miner. The disconnecting device for the model 21SC Joy shuttle car (Serial No. ET12404) was not locked out and suitably tagged prior to the performance of electrical work. This practice of not locking and suitably tagging the cable coupler for the shuttle car contributed to the occurrence of the fatal accident.
Related Fatal Alert Bulletin:
FAB02C15
APPENDIX B - Sketches
Sketch #1 Sketch #2
APPENDIX A
List of persons providing information and/or present during the investigation:
Calvary Coal Co., Inc.
James Napier ............... PresidentKentucky Department of Mines and Minerals
Randall Osborne ............... Superintendent
Asbury Caldwell ............... Safety Director
Rick Sandlin ............... Chief Electrician
Randy Roberts ............... General Mine Foreman
Kennard W. Morris ............... 1st Shift Section Foreman
Donald Maggard ............... 2nd Shift Mine Foreman
Ova Rice, Jr. ............... 3rd Shift Electrician
Ronnie Adams ............... 2nd Shift Electrician
David E. Roberts ............... Electrician / Rebuild Shop
Author D. Sizemore ............... Shuttle Car Operator
Jeffery L. Boggs ............... 3rd Shift Repairman
Freddie Wells ............... 3rd Shift Repairman
Henry McQueen ............... 1st Shift Beltman
Gary Maggard ............... 1st Shift Beltman
Eugene Pennington, Jr. ............... 2nd Shift Repairman
Tracy Stumbo ............... Chief Accident InvestigatorMine Safety and Health Administration
Michael L. Partin ............... Accident Investigator/Electrical Inspector
David Johnson ............... Chief Electrical Inspector
Tony Oppegard ............... General Counsel
Ron Turner ............... Mine Inspector
James W. Oakley, Sr. ............... Supervisory CMS&H Inspector
Charlie Fields ............... CMS&H Inspector
Patrick A. Stanfield ............... CMS&H Inspector - Electrical Specialist
Dennis J. Cotton ............... Accident Investigator/Mining Engineer
Stephen B. Dubina ............... Electrical Engineer