UNITED STATES DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
Accident Investigation Report
Surface Nonmetal Mine
(Mill)
Fatal Electrical Accident
SX/EW
Burro Chief Copper Company
Bayard, Grant County, New Mexico
Mine ID No. 29-00762
June 7, 1997
by
Omer H. Sauvageau
Mine Safety & Health Inspector
and
Daniel R. Lambert
Mine Safety & Health Inspector (Electrical)
Originating Office
Mine Safety and Health Administration
South Central District
1100 Commerce St., Suite 4C50
Dallas, Texas 75242-0499
Doyle D. Fink
District Manager
GENERAL INFORMATION
Xavier R. McSherry, 28 year old electrical supervisor, died at
about 1:10 a.m. on June 8, 1997, from injuries he received the
previous day at about 6:45 a.m. while testing a 480 volt electrical
circuit breaker. An arc phase fault occurred at the breaker
resulting in a flash that injured McSherry and two other miners.
McSherry had a total of 4« years of mining experience, and was
employed by Phelps Dodge Chino, Inc. at the open pit copper mine
neighboring the SX/EW. He had been an electrical supervisor at the
Chino Mines Company - Mine, an open pit mine, for about 7 weeks. He
had received annual refresher training in accordance with Part 48
in January 1997.
Walter Gomez and Larry Filkins received injuries to the face, hands
and arms from the flash. Both were supervisors at the Burro Chief
Copper Co., SX/EW, a copper solvent extraction (SX)- electrowinning
(EW) plant. Gomez had 16 years and Filkins 13 years of service at
Burro Chief Copper Co.
The SX/EW, owned and operated by Burro Chief Copper Company, was
located about 10 miles northeast of Bayard, Grant County, New
Mexico. The principal operating official was William S. Brack,
President. The plant employed forty two people and normally
operated three, 8 hour shifts per day, seven days a week.
D.J. Hays left a message on the Albuquerque New Mexico Field Office
answering machine at about 12:57 p.m., June 7, informing MSHA of
the accident. He made no other attempt on June 7 to contact the
agency.
Hays notified MSHA supervisor Thomas Loyd of the death at about
7:00 a.m. on June 8, 1997.
The Chino Mines Company - Mine, owned and operated by Phelps Dodge
Chino, Inc., an open pit copper mine, was located about 2-1/2 miles
northeast of Bayard, New Mexico adjacent to the SX/EW. The
principal operating official was also William S. Brack, President.
The mine employed 571 people and normally operated three, 8 hour
shifts per day, seven days per week.
The last regular inspection of the SX/EW was completed on January
23, 1997. Another inspection was completed in conjunction with
this investigation.
PHYSICAL FACTORS INVOLVED
Electrical power was supplied by Public Service Company of New
Mexico at 115,000 volts Alternating Current (AC), three phase and
was transformed to 13,800 volts AC at the main substation. The
power was fed to the 750 KVA transformer and reduced to 480 volts
AC, three phase, 900 full load amperes.
The equipment involved in this accident, a Westinghouse Seltronic
circuit breaker, received the 480 volt power from the transformer.
The circuit breaker was mounted in a Siemens motor control center
(MCC) and provided protection for the tank house feeder breaker.
The circuit breaker measured 16 inches high, 8 1/4 inches wide and
5 1/2 inches deep. It was improperly mounted in the MCC using 4
inch long 1/2 inch outside diameter threaded nuts. The nuts were
tightened onto 5/16 by 1 3/4 inch bolts which entered through the
back of the breaker. The nuts extended out of the recessed mounting
holes by about 1 inch, and were within 1/4 inches of the energized
terminals.
The circuit breaker was designed for mounting with .0250-20 x 1.5
inch Fillstar Head Steel Screws, Lockwashers and Flat Washers base
mounting hardware. The reverse installation, using bolts inserted
through the back of the breaker with extended nuts in the front,
negated the recess design of the mounting holes and allowed contact
between energized terminals and the extended nut.
The terminal cover, designed to insulate and prevent inadvertent
contact with terminals, was not in place at the time of the
accident. This determination was based on several factors. It was
not at the scene of the accident, employees could not remember
seeing it, and the company could not locate it during the
investigation.
The transformer feeding the breaker was an RATE Corporation, three
phase, 750 KA, connected 13,000 volt delta primary and 480 wye/277
volt secondary. Fuses in the F1 and F3 phases tested good.
However, both fuses in the F2 phase tested open. The top fuse
holder of the F2 phase showed signs of excessive heating and the
outer fuse body was charred. The other fuse showed a darkened spot
on the outside of the fuse case. The primary and secondary
windings on the transformer did not indicate a ground fault or
short circuit when tested.
The test meter used by McSherry was a Fluke Model 87 true RMS multi
meter, serial #3564030. The meter was set to test for AC voltage
and the display read Auto, AC, and MV. The test leads were still
intact. A continuity test indicated that they were good. The
outer insulation showed some heat damage but bare conductors were
never exposed. The two fuses in the meter, a BBS 1 amp and a KTK
15 amp, both tested good. The metal probe of the red test lead was
intact and was 3/4 inch long. The metal probe of the black test
lead was melted so that only 3/16 inch remained.
DESCRIPTION OF THE ACCIDENT
At 6:15 a.m., prior to McSherry's (victim) arrival at work, a power
outage occurred at the tank house of the SX/EW plant. William
Shannon, plant operator, went to the tank house and asked
employees if any of them could have caused a short circuit. None
of them had. Shannon then called the electrical shop at the open
pit to report the problem.
Shannon and C' shift supervisor Larry Filkins went to the MCC in
which the circuit breakers controlling the power to the tank house
were located. Shannon opened the feeder breaker and main breaker
cabinet door. He noticed that the feeder breaker was tripped and
reset it. He tested the main breaker to see if it was engaged and
apparently tripped it out. He reset it twice but it wouldn't hold.
Shannon left to prepare the SX/EW for shut down while Filkins
continued trying to reset the main breaker. Eventually Filkins got
the main breaker reset and called Shannon to tell him to put the
SX/EW back on line.
About 6:30 a.m. on June 7, 1997, Xavier R. McSherry (victim)
reported to work at the Chino Mines Company - Mine electric shop,
a few miles from the SX/EW plant. Walter Gomez (injured), A'
shift supervisor, reported to work at the SX/EW plant at the same
time. When McSherry learned that a power outage had occurred, he
proceeded to the SX/EW tank house MCC, checked and tripped the main
breaker.
Virgil Giambernardi, electrician, went to the tankhouse to shutdown
all 480 volt power and then joined McSherry, Shannon and Filkins at
the MCC. McSherry opened the main breaker panel door and tested
the breaker. After closing the panel door he tried to reset the
breaker unsuccessfully. He then shut off all of the breakers in
the MCC with the assistance of Giambernardi, who had returned from
the tank house.
McSherry asked Filkins to reset the breaker but he was also
unsuccessful. McSherry opened the panel door again to further test
the breaker. A' shift supervisor Walter Gomez arrived at the MCC
and Filkins began to explain the problems to him. Shannon was
leaving the area.
McSherry squatted in front of the panel and began testing the
breaker. When his multi tester probe contacted both a grounded
extension nut and the energized terminal on the circuit breaker, an
arc flash occurred in the main breaker box. McSherry's clothing
caught fire, and Gomez and Filkins were burned by the flash.
Shannon, Gomez and Filkins extinguished McSherry's burning clothes.
McSherry was placed in an ambulance alone and was transported to a
medical center. Doctors diagnosed him with second degree burns
over 75 per cent of his body and declared his condition as
critical. McSherry was then airlifted to University of New Mexico
Burn Center in Albuquerque, New Mexico. He died of his injuries the
following day.
CONCLUSIONS
The accident was caused by the improper installation of the circuit
breaker, in that the line terminal covers were missing and the base
mounting hardware used was not comparable to that available from
the circuit breaker manufacturer. This allowed the victim's test
probe to simultaneously contact the grounded extension nut used for
mounting the circuit breaker and an energized terminal. The
severity of injuries was increased because the victim was not
wearing protective clothing.
VIOLATIONS
Citation Number 7850488
Issued to Burro Chief Copper Company on
June 11, 1997 under the provisions of Section 103(j)/104(a) for
violation of 30 CFR 50.10.
On June 7, 1997, at 0645 hours, two shift supervisors from the
Burro Chief Copper Company, SX/EW, received serious burn injuries,
and an electrician supervisor from the Phelps Dodge Corporation,
Chino Mines Company Mine, received critical burn injuries, when a
480 volt electrical circuit breaker exploded [sic]. The 480 volt
circuit breaker was located in the Siemens Motor Control Center
west of the tank house at the SX/EW plant. On June 8, 1997 at 0110
hours the electrical supervisor died of his burn injuries.
The operator did not immediately contact the MSHA District or
Subdistrict office having jurisdiction over the SX/EW plant, or
call the MSHA headquarters office in Arlington, Virginia.
On June 7, 1997 at 1257 hours the operator did call the MSHA
Albuquerque, New Mexico field office, and left a message on the
answering machine. The message stated that there had been an
unplanned explosion when a 480 volt switch blew up, and burned a
[sic] electrician. The employee had been burned enough to where he
had to go to the hospital.
Citation Number 7850489
Issued to Burro Chief Copper Company on
June 11, 1997 under the provisions of Section 103(j)/104(a) for
violation of 30 CFR 50.12.
On June 7, 1997, at 0645 hours, two shift supervisors from the
Burro Chief Copper Company, SX/EW plant, received serious burn
injuries, and an electrical supervisor from the Phelps Dodge
Corporation, Chino Mines Company Mine, received critical burn
injuries, when a 480 volt electrical circuit breaker exploded. The
480 volt circuit breaker was located in the Siemens motor control
center West of the tank house at the SX/EW plant. On June 8, 1997
at 0110 hours the electrical supervisor died from his burn
injuries.
The operator did not preserve the accident site. On June 7, 1997
the circuit breaker that had exploded was removed and was replaced
by another circuit breaker.
On June 8, 1997 the operator called the MSHA Albuquerque New Mexico
field office supervisor and informed him that the electrical
supervisor had died.
The operator was told not to change anything at the accident scene.
On June 9, 1997 when the accident investigation began by MSHA, the
operator had already removed the replacement circuit breaker.
Citation Number 7859009
Issued to Burro Chief Copper Company on
June 11, 1997 under the provisions of Section 104(a) for violation
of 30 CFR 56.12002.
On 6/7/97 an accident occurred at the Siemens motor control center
located West of the tank house at the SX/EW plant. Three persons
received burns when an electrical circuit breaker exploded. One
person died from his burn injuries on 6/8/97.
The main circuit breaker in the Siemens motor control center,
located West of the tank house, was not properly installed. The
terminal covers for the top and bottom electrical terminals were
not in place and the base mounting hardware was not comparable to
that available from the manufacturer. The covers provide
insulation between phases and grounded metal parts near the
breaker. A short circuit to ground, was created by the black test
lead of the multi-tester being used to troubleshoot the electrical
problem at the motor control center, when it came in contact with
the bottom electrical terminal and the extended metal nut used for
securing the breaker to the motor control center.
Citation Number 7859010
Issued to Burro Chief Copper Company on
June 11, 1997, under the provisions of Section 104(a) for violation
of 30 CFR 56.20011.
On 6/7/97 an accident occurred at the Siemens motor control center
located West of the tank house at the SX/EW plant. Three persons
received burns when an electrical circuit breaker exploded. One
person died from his burn injuries on 6/8/97.
The warning sign on the door of the main circuit breaker, was not
adequate. The word "danger" on the sign, was almost entirely
removed when the opening in the cubicle door, was enlarged (made
longer) for the movement of the circuit breaker handle. The sign
was difficult to read, by being placed on the bottom of the door
under the circuit breaker handle.
This condition created a Fire, Shock , and Electrocution hazard to
persons working on the circuit breaker.
Citation Number 7859093
Issued to Burro Chief Copper Company on
August 19, 1997, under the provisions of Section 104(a) for
violation of 30 CFR 56.12017.
On 6/7/97 an accident occurred at the Siemens motor control center
located West of the tank house at the SX/EW plant. Three persons
received burns when an electrical circuit breaker exploded. One
person died from his burn injuries on 6/8/97. The three phase, 480
volt circuit, was not de-energized and locked out before doing work
on the circuit, hot-line tools, was not used and protective
clothing, was not being worn. This condition created Burn, Shock,
and Electrocution hazards to persons at the SX/EW plant.
/s/ Omer H. Sauvageau
/s/ Daniel R. Lambert
Approved By: Doyle D. Fink, District Manager
Related Fatal Alert Bulletin: [FAB97M34]
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