DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
ACCIDENT INVESTIGATION REPORT
SURFACE AREA OF UNDERGROUND MINE
Richland Mine (I.D. No. 15-17232)
Pleasant View Mining Co., Inc.
Madisonville, Hopkins County, Kentucky
April 7, 1996
Originating Office - Mine Safety and Health Administration
100 YMCA Drive, Madisonville, Kentucky 42431-9019
Rexford Music, District Manager
Pleasant View Mining Co., Inc., Richland Mine, is located 1.1 miles North of the intersection of Kentucky 70 and Richland - Manitou Road in Hopkins County, Kentucky. The Richland Mine began production on August 25, 1992. This one section mine is accessed by four drift openings into the Kentucky No. 11 coalbed and the mining height averages 78 inches. The mine utilizes one continuous mining machine to extract 1600 tons daily on one eight-hour production and one maintenance shift. Shuttle cars are used to transport coal from the continuous mining machine to the mainline conveyor belt. Battery and diesel powered scoops are used to convey materials, and the miners are transported with diesel mantrips. All self propelled haulage equipment is rubber tired.
The principal officers of Pleasant View Mining Co. Inc., Richland Mine were listed as follows:
Gary E. Peyton................................President
Chester A. Joseph.............................Maintenance Foreman
Paul Cotton....................................Safety Director
The last regular safety and health inspection (AAA) of this mine was completed on April 5, 1996.
DESCRIPTION OF THE ACCIDENT
On Sunday, April 7, 1996, at 1:30 p.m., William Wade Evans, second shift mine foreman, reported for work. At approximately 2:00 p.m. Evans traveled underground to conduct an examination of the working section. Upon arrival at the No. 2 Belt Drive Conveyor, Evans discovered that the underground portions of the mine did not have electrical power. He returned to the surface to ensure that the mine fan was operating and then traveled to the mining section to complete his examination. Upon completion, Evans returned to the surface and, at 2:40 p.m., he telephoned Chester A. Joseph, maintenance foreman, and Danny Griffin (victim), superintendent, to inform them that the underground portions of the mine did not have electrical power. He also notified Gary W. Peyton (injured), purchasing agent, and son of President Gary E. Peyton.
Griffin and Joseph arrived around 3:00 p.m. and accompanied Evans to the main high voltage substation located on the surface, which supplies 7200 volts of resistance-grounded alternating current to the surface and underground electrical equipment. Once inside the fenced-in area, Joseph made three unsuccessful attempts to close the oil circuit breaker (OCB #1) which supplied the high voltage power to the underground portions of the mine.
Examination by Joseph revealed that the operative induction-disk type current relays and ground fault relay, which are used for protection of electrical circuits, did not give a target indication (flags) as to why the breaker failed to close. The mechanical target indication systems (flags) were functional.
At 4:05 p.m., Gary W. Peyton telephoned James O. Suthard, owner of Power Electric and electrical contractor for the mine, to come and assist in restoring the underground power. Suthard told Peyton, by mobile phone, that he was enroute to examine a 69,000 volt air switch located on an adjacent farmland. This air switch provides power to the Richland Mine's main substation. Peyton and Griffin then drove to join Suthard at the 69,000 volt air switch. After some discussion, Peyton and Griffin returned to the main substation at the Richland mine.
While Peyton and Griffin were with Suthard, Joseph opened the three knife-blade type disconnect switches in order to provide a visible disconnect between OCB #1 and the underground high voltage mine power cable (see electrical diagram). Then Joseph and Evans traveled underground to the high voltage vacuum circuit breaker (No. 1 VCB) enclosure located one crosscut inby the mine portal. Joseph opened the No. 1 VCB to isolate the underground mine power system from the mine power high voltage cable. Joseph and Evans then traveled back to the substation and made another unsuccessful attempt to close OCB #1 with the mine power cable disconnected. Joseph then closed the knife-blade disconnects at OCB #1, thereby completing the circuit to the mine power cable, but did not attempt to close OCB #1 again.
Meanwhile, Suthard had discovered a loose phase conductor connection at the 69,000 volt air switch and telephoned Griffin at the Richland Mine to request that the entire electrical system be deenergized until repairs were completed. Once the loose connection had been repaired, Suthard drove to the Richland Mine substation to assist Joseph with determining the cause of the underground power problem. When Suthard arrived, he entered the substation and attempted to close OCB #1. Suthard stated the OCB #1 tripped, but there were no target indicators (flags) on the protective relays which would have alerted him to electrical faults in the system.
Suthard then opened the knife-blade disconnects between OCB #1 and the underground high voltage mine power cable and attempted to close OCB #1 approximately six times. Suthard removed a trip circuit from the Atkinson ground check monitor circuit and attempted to close the breaker approximately two additional times without success. He then reconnected the trip circuit and instructed Joseph to bridge a connection between the pilot wire and ground wire circuits. He then unsuccessfully attempted to close OCB #1 approximately two more times. Suthard removed the trip circuit again and once again attempted to close OCB #1. Layne Dickerson, Power Electric employee, arrived shortly thereafter and asked Suthard if the problem might be in the door interlock switch. Suthard examined the door interlock switch, then instructed Joseph to open the pilot wire to ground wire connection and close the door. Suthard reconnected the trip circuit and successfully closed the OCB #1 three times, leaving it energized for approximately 60 seconds each time to ensure that it was functioning properly.
Once this was done, Suthard opened OCB #1 and closed the knife- blade disconnects to the underground circuit. He then closed OCB #1, but it immediately tripped. All three protective relays gave target indications (flags) that the system had a three-phase fault. Suthard subsequently opened the knife-blade disconnects to the underground mine power cable and told Peyton, Evans, Griffin, and Joseph that the system had a phase-to-phase fault in the underground circuit. Joseph then secured (locked out) the OCB #1 knife-blade disconnect switches by locking the access door to the enclosure in which these switches were housed.
Suthard and Peyton went to the pit area while Griffin, Joseph, and Evans returned to the No. 1 VCB enclosure located one crosscut inby the portal. Joseph tested the input mine power cable with a Simpson Triplett Digital 2202 volt-ohm meter. The meter read the primary of the two potential transformers which indicated to Joseph that he had found the cause of the problem. Joseph thought the two potential transformers were faulted surge arresters. Believing that the problem had been identified, Griffin then went to the pit area and told Suthard and Peyton that the results of Joseph's troubleshooting indicated that two surge arresters were shorted. Suthard left the mine, while Griffin and Peyton returned to the mine office.
Back at the underground No. 1 VCB located one crosscut inby the portal, Evans watched while Joseph disconnected two potential transformers which Joseph mistakenly identified as surge arresters. Thinking the problem had been corrected, Evans traveled one crosscut to the mine portal and called Griffin from the underground mine phone at approximately 8:15 p.m. Evans told Griffin that the electrical repairs had been completed and that he and Joseph were ready to go to the substation to energize the system. Griffin asked if the No. 1 VCB was opened or closed. Evans told Griffin that Joseph left the No. 1 VCB open in order to see if OCB #1 would close and energize the mine power cable. Griffin then asked if Joseph had isolated the surge arresters. Evans replied that the surge arresters had been isolated. Griffin and Peyton apparently then left the mine office and went to the substation. Evans joined Joseph at the underground No. 1 VCB enclosure.
Griffin, without communicating with or having authorization from Joseph, unlocked the OCB #1 access door, and utilizing a hot stick, closed the knife blade disconnects which connected the mine power cable to OCB #1.
At 8:20 p.m., Griffin closed the OCB #1, and Evans and Joseph heard an explosion accompanied by a flash of light that appeared to come from the area of the surface substation. While hurrying to determine the cause, Evans and Joseph encountered Peyton and Griffin in a company truck. Peyton stopped long enough to tell the men that he and Griffin had been badly burned and were going to the hospital. Shortly after their arrival at Regional Medical Center in Madisonville, Kentucky, Griffin was life-flighted to the University of Louisville Burn Center in Louisville, Kentucky. On Tuesday, April 9, Peyton was transported to Vanderbilt Hospital in Nashville, Tennessee. At 3:05 a.m. on Thursday, April 18, Griffin died as a result of his injuries.
Tom Dupree, Coal Mine Safety and Health Supervisor, was notified of the accident by Paul Cotton, Safety Director, at 9:17 p.m. The investigation team arrived at the mine at 10:20 p.m. and began a joint investigation with the Kentucky Department of Mines and Minerals. Employees of Pleasant View Mining Co., Inc. assisted during the investigation.
The accident scene was examined, measurements and photographs were taken, and related equipment was examined. Interviews of persons who had knowledge of the accident were conducted by MSHA and the Kentucky Department of Mines and Minerals at the Kentucky Department of Mines and Minerals office in Madisonville, Kentucky, on April 9. Peyton was later interviewed on June 3.
Records indicated that required training for the employees at Richland Mine had been conducted in accordance with the requirements of 30 CFR, Part 48.
The required Electrical training for Suthard and Joseph was up to date and conducted in accordance with the requirments of 30 CFR, Part 48.
PHYSICAL FACTORS INVOLVED
The investigation revealed the following factors relevant to the occurrence of the accident:
- A routine examination of the mine during an idle shift
revealed that the underground portions of the mine were not
provided with electrical power.
- Suthard and Joseph, both qualified electricians, made several
unsuccessful attempts to reenergize the underground power system
by closing 0CB #1.
- Tests conducted by Suthard identified a three-phase fault
within the system which supplied power to the mine.
- Before leaving the substation, Joseph locked out the knife-
blade disconnect switches for OCB #1. Troubleshooting procedures
by Joseph mistakenly indicated that a fault had occurred in
two potential transformers which had been incorrectly identified
as defective surge arresters. Suthard left the mine property
after concluding that the problem had been identified by Joseph.
- Joseph disconnected two potential transformers (which were not
defective), and assumed that the problem with the electrical
circuit had been corrected.
- Joseph (qualified electrician) did not authorize Griffin (who
was not a qualified electrician) to unlock the OCB #1 access
door, close the knife-blade disconnect switches or close OCB #1.
- Griffin, possessing an extra key to the OCB #1 access door and
believing that the system would energize, unlocked the access
door and closed the knife-blade disconnect switches for OCB #1.
Griffin then closed the oil circuit breaker (OCB #1) and an
explosion occurred which resulted in serious injuries to Griffin
and Peyton. Griffin subsequently died of his injuries at 3:05
a.m. on Thursday, April 18.
- Following the accident, MSHA's analysis revealed that all three
protective relays had tripped, indicating that a short circuit
condition was present in the mine power cable. Subsequent
examination revealed a three-phase fault in a splice in the high
voltage mine power cable connecting the substation to the first
high voltage No. 1 VCB switch. The faulted area was not
initially discovered because it was located in a section of the
cable which had been buried near the substation.
- Investigators determined that the splice originally had been
properly constructed with the correct materials. This was
evidenced by the fact that the splice had functioned properly
since the cable was installed in 1992.
- The mine power cable is a 2/0 AWG, 3/C type MP-GC, 15 KV.
- The oil circuit breaker was manufactured by Westinghouse.
- The circuit breaker nameplate, listing the current
interrupting rating, was not found due to the destruction caused
by the explosion and fire.
- Repeated closing of the circuit breaker by the qualified electricians may have exceeded the standard duty cycle of the breaker. The duty cycle is based on a maximum number of fault current interruptions within a specified time period. Repeated breaker interruptions in a short period of time can cause the oil to overheat and expand increasing the potential for the breaker to catch fire and self destruct or explode.
The accident sequence began when a fault condition occurred on a high voltage system suppling 7200 volts to the underground portions of the mine, causing the #1 oil circuit breaker (OCB #1) inside the surface substation to deenergize. This breaker was repeatedly closed throughout the troubleshooting process. The accident potential was increased when a maintenance foreman mistakenly concluded that the fault had been corrected. Griffin, who was not a qualified person, unlocked the door which housed the OCB #1 knife-blade disconnect switches and closed the knife- blade disconnect switches. The accident occurred when the oil circuit breaker tank enclosure exploded as Griffin closed OCB #1 under fault conditions, spraying him with burning oil. Peyton and Griffin were both seriously injured. Griffin later died on April 18, as a result of his injuries.
- 103(K) Order No. 4276845 was issued to Pleasant View Mining Co. Inc. to assure the safety of all persons in the affected area.
Respectfully submitted by:
Related Fatal Alert Bulletin: