DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
South Central District
ACCIDENT INVESTIGATION REPORT
UNDERGROUND NONMETAL MINE
[POTASH]
FATAL ELECTRICAL ACCIDENT
[SURFACE]
Hobbs Potash Facility, ID No. 29-00170
New Mexico Potash Corp.
Hobbs, Lea County, New Mexico
August 23, 1995
By
Ronald M. Mesa
Special Investigator
Henry J. Mall
Mine Safety and Health Inspector
South Central District Office
1100 Commerce Street, Room 4C50
Dallas, Texas 75242-0499
Doyle D. Fink
District Manager
GENERAL INFORMATION
On August 23, 1995, Rufus Beene, electrician, age 59, and Wilburn Miller, surface maintenance superintendent, age 59, received electrical flash burns when Beene made contact between an electrical conductor and the enclosure with a metal hand tool. Beene was switching two incoming 480 volt leads on the line side of the motor control center (MCC) main breaker to obtain correct motor rotation. Beene had a total of twenty-seven years mining experience, and nine years as an electrician, all at this mine site. Miller had a total of twenty-six years mining experience all at this mine site. Beene died on September 22, 1995, at University Medical Center in Lubbock, Texas, due to the injuries he received in the accident. Miller has recovered and returned to work.
The Hobbs Potash Facility, was located approximately 31 miles north east of Carlsbad, New Mexico. The mine began producing potash ore in 1965. Continuous miners cut the ore from the underground room and pillar workings at depths ranging from 800 to 2200 feet within the mine. The mined material was transported to the surface, crushed, leached, crystallized and sized. Finished products, potassium chloride and muriate of potash, were shipped to a variety of agricultural and industrial users world wide. A total of 11,000 tons per day of raw ore was produced every day by 140 employees working two 12-hour shifts a day, seven days a week.
Operating officials were:
Melvin Pyeatt........Vice President of Operations
Curtis Davidson.....Safety Manager
Duane Morris........Underground Safety Supervisor
Safety Manager Curtis Davidson notified MSHA Supervisor Jerry Millard, Carlsbad Field Office, of the accident at approximately 8:00 p.m. on August 23, 1995. A nonfatal accident investigation was started on the same day. On September 22, 1995, Curtis Davidson notified Jerry Millard that Beene had died of his injuries in Lubbock, Texas. A fatal accident investigation was started on September 25, 1995.
Mine employees were not represented by a union.
The mine had an approved MSHA 30 CFR Part 48 Training Plan that was last revised in March 1993. Company records showed that Mr. Beene had received all the required MSHA training.
Information for this report was obtained by interviewing company
officials and employees during the on-site investigation. The
last regular inspection was conducted on June 6, 1995.
PHYSICAL FACTORS INVOLVED
The scene of the surface accident was the counter current decontaminate (CCD) area substation building. The building was divided into the south and north rooms. Located in the south room of the building were the CCD distribution switchgear and MCC. Inverse Time Element (ITE) was the manufacturer of the CCD distribution switchgear. The hydro separator MCC involved in the accident was located in the north room of the building. Westinghouse was the manufacturer of the hydro separator MCC.
The CCD distribution switchgear in the south room was fed 480 volt, three phase electrical power from an ITE 1000 KVA pad mounted transformer located outside the building. The transformer was a class AO and connected 4160/480 volts wye/wye. An oil switch was mounted on the side of the transformer for de-energizing the primary 4160 volt feed.
The hydro separator MCC in the north room was equipped with a main breaker. The molded case breaker was an 800-ampere 480 volt, three phase Westinghouse M.A. breaker, serial number 1278C73G11. The breaker was being fed with three 500 MCM type THW single conductors from a Spokane 300 KVA pad mounted transformer located outside of the building. The transformer was a class OA and connected 4160/480 volt wye/wye. The primary 4160 volt feed to the transformer could only be de-energized by opening the #11 circuit breaker located approximately 1350 feet away in the east room of the hoist house.
A common 500 MCM, 5 KV rated power cable fed the 300 and 1000 KVA transformers. The power cable ran underground from the CCD substation building manhole to a distribution manhole that was located centrally to the loadout, compactor and CCD substations.
In the distribution manhole the 500 MCM power cable was spliced to the underground 750 MCM 5 KV rated feeder cable that terminated at the No. 11 circuit breaker in the hoist house. A section of this power cable between the distribution and CCD manholes had been found to have caused the power failure which occurred early in the day. A section of 350 MCM, 15 KV rated power cable was temporarily installed above ground between the two manholes to replace the faulted section of cable.
An auxiliary standby generator was located at the CCD substation.
The generator provided emergency backup power for the essential
CCD motor circuits in case of a power failure. The generator
start up switching sequence was to turn OFF the CCD main
breakers, start the generator, turn on the auxiliary power
disconnect switches and restart the essential motor circuits.
The reverse procedure was used for returning to utility power.
DESCRIPTION OF THE ACCIDENT
On August 23, 1995, Rufus Beene, electrician and Wilburn Miller, surface maintenance superintendent reported for work at 7:00 a.m., their regular scheduled starting time.
At approximately 8:30 a.m. a power failure occurred in the 4160 volt power circuit fed by the No. 11 breaker in the hoist house. The generator was put on line to maintain essential CCD motor circuits. The electrical crew of Beene, Randy Warren, electrician and Charles Halliburton, electrician began to isolate the faulted section of the power circuit. At about 11:00 a.m., they discovered that a flooded manhole had caused a ground fault in the 500 MCM power cable to the CCD substation transformers.
The No. 11 circuit breaker for the 4160 volt cable in the hoist house was locked out. All three electricians had de-energized and locked out the No. 11 switch at different times during the troubleshooting and repair process. The grounded section of power cable was bypassed with the temporary cable that was spliced into the power circuit at the distribution manhole and at the CCD substation manhole. When the splices were completed, the auxiliary generator circuit was shut down and the No. 11 circuit breaker was re-energized. When power was checked at the CCD substation, it was found that the phasing was reversed during the splicing operation.
The crew made a decision to attempt phase reversal on the secondary 480 volt side of the transformers instead of reversing the new primary 4160 volt splices. Before they reentered the CCD substation building they decided to check the 480 volt feed to the substation switchgear to determine the feasibility of reversing the phase rotation. At this time the substation building lights, that are powered from the ITE switchgear in the south room, were ON.
Beene said he would check the hydro separator MCC and he entered the north room of the building. Warren and Halliburton went into the south room of the building to check the ITE distribution switchgear.
Warren and Halliburton tripped OFF the CCD distribution switchgear main breaker in the south room and the lights in the CCD substation building went out. Then they opened the oil switch on the primary side of the 1000 KVA transformer. Utility and generator power was checked to ensure that it was OFF to the south room switchgear.
About this time, Miller arrived to check on the work progress. Warren and Halliburton were in the process of checking the south room switchgear. Miller observed Beene in the north room with a flash light in his mouth checking the hydro separator MCC. Miller then held the flashlight for Beene. Beene checked for auxiliary generator power to the hydro separator MCC and for power on the bottom (load side) of the main breaker. The cover was removed from the molded case breaker. Beene used a rachet wrench with an allen socket and attempted to loosen the energized top right (load side) lug of the breaker. A flash occurred when the handle of his metal ratchet contacted the frame of the MCC. The MCC was still energized by the 300 KVA transformer.
First aid was administered by company officials to Beene and
Miller. They were transported to Guadalupe Medical Center in
Carlsbad, New Mexico. They were then flown to the University
Hospital in Lubbock, Texas for treatment of their injuries.
Miller received 2nd and 3rd degree burns on approximately 10-15%
of his body. Beene received 2nd and 3rd degree burns on
approximately 35-40% of his body.
CONCLUSION
The causes of the accident were the failure to de-energize and
lock out the electrical power and the contact made with the wrench
between the hydro separator MCC enclosure and the energized 480
volt lug.
VIOLATIONS
Citation Number 4330828, was issued under the provision of Section 104(a), for a violation of 30 CFR 57.12017:
Two (2) employees were seriously burned when the electrician failed to de-energize the electrical circuit that he was working on.
This citation was terminated on September 5, 1995.
Safety meetings were held with all the employees on the cited standard and proper lock-out procedures.
This citation was modified on September 28, 1995. The condition or practice was modified to add:
[The electrician involved in the accident passed away on September 22, 1995 in Lubbock, Texas, from the injuries he had received from the electrical burns.]
Citation Number 4330829, was issued under the provision of Section 104(a)for a violation of 30 CFR 57.12018:
The principal power switches shall be labeled to show which units they control.
This citation was terminated on September 5, 1995.
Signs were posted on the transformer fence enclosures.
This citation was modified on September 28, 1995. The condition or practice was modified to add:
[The electrician involved in the accident passed away on September 22, 1995 in Lubbock, Texas, from the injuries he had received from the electrical burns.]
Respectfully submitted by:
/s/ Ronald M. Mesa
Special Investigator
/s/ Henry J. Mall
Mine Safety and Health Inspector
Approved By:
Doyle D. Fink
District Manager
Related Fatal Alert Bulletin:
[FAB95M34]