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District 1


Primrose Slope (I.D. No. 36-04629)
Primrose Coal Co.
Good Spring, Schuylkill County, Pennsylvania

March 30, 1995


Leonard P. Sargent
Coal Mine Safety and Health Inspector

Elio L. Checca
Supervisory Electrical Engineer

Roy D. Davidson
Coal Mine Safety and Health Inspector (Electrical Engineer)

Dennis Hagy
Coal Mine Safety and Health Inspector (Electrical)


William C. Hughes
Coal Mine Safety and Health Inspector (Electrical)

Originating Office - Mine Safety and Health Administration
Room 3128-D Penn Place, 20 North Pennsylvania Avenue
Wilkes-Barre, Pennsylvania 18701
Larry E. Brown, Acting District Manager


Primrose Slope, MSHA I.D. No. 36-04629, an underground anthracite mine is operated by Primrose Coal Co., a partnership, with David S. Himmelberger and Jared D. Himmelberger, partners. The mine employs 7 miners, working two production shifts per day, 5 days per week. The principal company official at this mine is David S. Himmelberger, partner and foreman.

The advancing coal faces are drilled, loaded with permissible explosives and blasted off the solid. The coal is either washed down the pitch by water pressure to an air operated chain conveyor or dragged down the pitch to the chain conveyor by an electric driven drag. The coal from the chain conveyor is discharged into the slope conveyance (gunboat) for hoisting to the surface.

The last Mine Safety and Health Administration (MSHA) complete Safety and Health inspection (AAA) was conducted January 27 through February 10, 1995.


On Thursday, March 30, 1995, at 1:30 p.m., the second shift employees began their regular work duties. Work duties were assigned by David S. Himmelberger, foreman. A preshift examination had been conducted by Himmelberger on March 30, 1995, between 12:30 p.m. and 1:30 p.m.

Robert S. Wolfe, Robert A. Klouser, Jr., and Charles J. Frederick, (victim) traveled underground on the mantrip. This was Frederick's second consecutive shift.

Wolfe and Klouser proceeded to the No. 1 chute and washed loose coal down to the conveyor. Frederick was operating the air driven chain conveyor loading coal into the main slope coal car. At approximately 5:45 p.m., Wolfe and Klouser noticed a loss in water pressure from the wash pump, and a few seconds later heard Frederick cry out. Approximately 15 seconds later a muffled cry was heard. Wolfe descended the ladder from No. 1 chute to the gangway to determine what had happened. As Wolfe approached the gangway, he observed Frederick lying face down on the mine floor between the mine car and slurry pump. Wolfe stepped off the wooden ladder while holding the steel cable to a 480 volt A.C. electric coal drag in his left hand when his right foot contacted the rail, resulting in an electrical shock to Wolfe. He fell forward onto the mine car receiving another electrical shock. Wolfe then yelled to Klouser, "Don't touch anything, go to the mine phone, tell Lucas to turn the underground power off". Darryl Lucas, hoist operator, de-energized the underground electrical power and notified Klouser that power was off. Wolfe and Klouser moved Frederick approximately 10 feet, started CPR and notified Lucas to call mine rescue and ambulance personnel. CPR was continued for approximately 10 minutes. No pulse or breathing was detected. Wolfe and Klouser loaded Frederick into the mine car and informed Lucas to bring them outside. CPR was continued on the way to the surface and until medical technicians arrived. Hegins Ambulance Service arrived at the mine at 6:13 p.m. The Advanced Life Support System (ALSS) arrived at 6:15 p.m. Paramedics with ALSS were in radio contact with Dr. Bortz at the Pottsville Hospital who was advising medical treatment for the victim.

At 7:35 p.m., Dr. Bortz informed the ALSS crew to stop all medical treatment. At 7:40 p.m., Frederick was pronounced dead by Paul F. Vuksta, Deputy Coroner.


The investigation revealed the following factors relevant to the occurrence of the accident.

  1. Three-phase electrical power for the mine was purchased from Pennsylvania Power and Light Company at 12,470 volts alternating current (a.c.) and transformed down to 480 volts a.c. for mine utilization. The three 167 KVA pole mounted transformers used for this purpose were connected wye solid grounded on the primary and delta ungrounded on the secondary.

  2. The 480 volt ungrounded delta secondary provided electrical power to both surface and underground equipment.

  3. No intentional ground to earth was provided for the frames of the surface equipment. However, the frames of all the surface equipment were connected together with a grounding conductor and the contact resistance of the equipment to earth was measured as approximately 30 ohms with a ground resistance tester.

  4. The frames of all underground equipment were connected to an earth ground field located on the surface. This earth ground field with all the underground equipment connected, measured approximately 10 ohms with a ground resistance tester.

  5. The series resistance of 40 ohms (30 plus 10) between the surface and underground earth grounds would have been much less at the time of the accident than when measured during the accident investigation. When the accident occurred, the coal car was setting on top of a mine rail that was immersed in a pool of water caused by the washing of loose coal down the No. 1 chute to the conveyor. The coal car, mine rail and several underground electric pumps were located in this immediate area of water, slurry and sludge. When the measurements were taken at the time of the accident investigation, this area had dried up considerably and the coal car was located on the surface and not underground.

  6. The surface equipment frames were not connected to the underground equipment frames by a grounding conductor.

  7. One phase conductor was faulted to the frame inside the 3- phase 480 volt, 30 horsepower fan motor located on the surface.

  8. A three phase, 480 volt 3.7 horsepower submersible pump, located approximately 80 feet from the accident location, was used to provide water to wash coal from the face area. Robert S. Wolfe, who was working in the face area at the time of the accident, stated the water used to wash coal stopped flowing a few seconds prior to his hearing the victim cry out.

  9. Having heard the victim cry out, Wolfe immediately traveled from the face area to the accident scene (approximately 50 feet) where he received multiple electrical shocks. The first shock occurred when his right foot contacted the mine rail under the coal car and his left hand was holding a steel cable for the drag connected to the underground grounding system. Wolfe then used his hand on the coal car to push himself from the mine rail and received another shock. Wolfe stated that he received additional electrical shocks while standing on the mine floor and touching nothing else. Wolfe did not know if these shocks ceased before or after the mine power was cut off. Wolfe stated the rubber boots that he wore leaked.

  10. MSHA investigators authorized the removal of the 3.7 horsepower submersible pump motor and its 30 ampere fuses on March 30, 1995 because of possible flooding near the accident scene.

  11. On April 3, 1995, a Simpson Model 260, Volt-Ohmmeter was used to test the insulation of the pump motor that had been brought to the surface. Two phases were measured as 0.0 ohms between the motor terminals and the pump motor frame. The third phase initially was measured as 9.8 ohms, but when the motor cover was removed, this reading increased to 16.7 ohms. When tested the next day, the resistance increased to 30 ohms as the motor dried.

  12. One Bussmann Type FRS-R-30, 30 ampere fuse and two Bussmann Type RES renewable 30 ampere fuses were installed to provide protection for the 3.7 horsepower submersible pump. All fuses were checked with a Simpson Model 260, Volt Ohmmeter and found to be open. The fuses protecting two of the phases opened instantaneously when insulation on two phases in the pump motor failed and allowed a double phase-to-motor frame fault to occur. The third fuse opened after Mr. Frederick was electrocuted and Mr. Wolfe was shocked, but before mine electrical power was de-energized by Mr. Lucas. This occurred because of a grounded phase in the submersible pump and a different phase to frame fault in the surface fan which allowed current to flow through earth in the area of the accident and other parallel paths between the surface and underground grounding systems. The third fuse opened after some time delay since the earth resistance between the surface and underground grounding systems caused a limited fault current and not a short circuit current to flow through the fuse.

  13. A Simpson Model 260, Volt-Ohmmeter was used to measure the resistance between the coal car, the one-inch steel hoist rope, the surface hoist equipment and the ground wire connected to the surface fan motor. These measurements indicated these components were electrically continuous. Therefore, there was a low resistance current path between the coal car and the surface fan motor.

  14. A 480 volt, 30 horsepower slurry pump was located near the track at the accident scene and was not energized at the time of the accident. A Simpson Model 260, Volt-Ohmmeter was used to verify the interconnection of the grounding conductor for the 3.7 horsepower submersible pump and the 30 horsepower slurry pump. Therefore, there was a low resistance current path between the submersible and slurry pump frames.

  15. The victim was located between the frame of the 30 horsepower slurry pump and the coal car. The distance between the pump frame and coal car was approximately 20 inches.

  16. MSHA personnel from the Pittsburgh Safety & Health Technology Center recreated the electrical conditions at the mine that caused the electrocution. These tests indicated the victim could have been exposed to 464 VAC and a current of 0.236 amperes.

  17. A ground fault on one phase of an ungrounded delta system causes full line to line voltage above ground to appear on the other two phases of the system. In a system where insulation can become deteriorated from age and use, the additional 73 per cent voltage stress often results in insulation failures in other parts of the system after the first grounded phase condition occurs.

  18. Lightning was not detected by the GDS National Lightning Detection Network for the search period March 30, 1995, 12:00:00 AM EST through March 30, 1995, 11:59:00 PM EST within a 25-mile radius of the search location.

  19. At the time of the accident, the victim was extremely wet and wore new rubber boots that appeared to be in excellent condition. Electrical burn marks were found on the little finger and palm of his right hand.


Electric power was supplied to all surface and underground equipment from one set of ungrounded delta transformers. A grounded phase in the 3.7 horsepower submersible pump located in the underground area of the mine and a different grounded phase in the main fan located on the surface created a double phase-to- ground fault. The electrocution occurred because the method of grounding the electrical equipment did not prevent the metal enclosures from being energized when a grounded phase occurred. In addition, the separation of the surface and underground equipment grounding conductors prevented the overcurrent devices from removing power from the faulted equipment. This inadequate grounding allowed a fatal voltage to persist between the metal enclosures of the surface equipment, metal enclosures of the underground equipment, and the earth. The victim contacted the slurry pump frame and the coal car, bridging the separation of the surface and underground grounding circuits and was electrocuted.


  1. A 103(k) Order, No. 3082238, was issued to assure the safety of all persons at the mine until an investigation was completed by MSHA.

  2. A 104(a) Citation, No. 4152240, CFR 30, Section 77.701 was issued for the 3-phase 480 volt equipment in use at the mine was not grounded by methods approved by an authorized representative of the Secretary.

  3. A 104(a) Citation No. 4149821, CFR 30, Section 75.518 was issued for the 3-phase 480 volt 3.7 H.P. motor on the Flygt pump was not provided with an automatic circuit breaking device of the correct type and capacity that would de-energize all three phases in the event any phase is overloaded.

Respectively Submitted by:

Leonard P. Sargent
Coal Mine Safety & Health Inspector

Elio L. Checca
Supervisory Electrical Engineer

Roy D. Davidson
Coal Mine Safety & Health Inspector (Electrical Engineer)

Dennis Hagy
Coal Mine Safety & Health Inspector (Electrical)

William C. Hughes
Coal Mine Safety and Health Inspector (Electrical)

Approved by:

Larry E. Brown
Acting District Manager for Coal Mine Safety and Health District 1

Related Fatal Alert Bulletin:
Fatal Alert Bulletin Icon [FAB95C08]