DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
ACCIDENT INVESTIGATION REPORT
SURFACE NONMETAL MINE
FATAL ELECTROCUTION ACCIDENT
Dell Conractors Material Inc. - ID. No. 28-00035
Dell Contractors Materials Inc.
Clifton, Passaic County, New Jersey
December 8, 1995
Carl W. Liddeke
Supervisory Mine Safety and Health Inspector
Carl A. Onder
Mine Safety and Health Inspector
Gustave E. Paul
Mine Safety and Health Inspector (Electrical)
Mine Safety and Health Administration
230 Executive Drive, Suite 2
Cranberry Township, Pennsylvania 16066-6415
James R. Petrie
David McNaught, primary crusher operator, age 34, was electrocuted on December 8, 1995, at approximately 11:00 a.m. when the metal walkway on which he was standing became energized. McNaught was employed by Dell Contractors Materials Inc. He had worked 1 week as a primary crusher operator for this company and 1 year 4 months operating their concrete recrush plant. He had a total of 10 years mining experience.
Dell Contractors Materials Inc. was a crushed stone mining operation located in Clifton, Passaic County, New Jersey. The principle operating officials were John Gilham, general manager, and Bruce P. Pascale, superintendent. The mine normally operated one 8-10 hour shift a day, 6 days a week. A total of 18 persons was employed at the minesite.
Stone was mined by drilling and blasting multiple benches.
Broken stone was loaded by front-end loaders into haul trucks which transported the material to the primary crushing and screening plant. Crushed stone products were stockpiled for sale to customers.
The last regular inspection of this operation was completed by MSHA on October 18, 1995.
Pascale notified James Petrie, MSHA Northeastern district
manager, of the accident on December 8, 1995, at 1:00 p.m. by
telephone. Mine Safety and Health Inspector Carl A.
Onder arrived at the mine site on December 9, 1995, and started
the accident investigation. Electrical Mine Safety and Health
Inspector Gustave E. Paul and Supervisory Mine Safety and Health
Inspector Carl W. Liddeke also participated in this
PHYSICAL FACTORS INVOLVED
A galvanized water pipe, 1-inch outside diameter by 3/4-inch inside diameter by 18 feet in length, which provided water for the dust control sprays on the primary crusher, extended out of the ground adjacent to the walkway. A 2-inch wide strap of conveyor belting was fastened to the walkway railing to support the pipe. Another piece of conveyor belting was taped to the first vertical metal support of the railing to prevent the water pipe from rubbing against it. This piece of conveyor belting was worn through, and allowed the water pipe to make contact with the metal support. Evidence of arcing was observed where the 1-inch water pipe had made contact with the first vertical support. Electrical conduits, which provided electrical power from the main electrical control room to various electrical junction boxes within the primary plant, also extended out of the ground near the water pipe.
A portable generator provided power (480 volts-3 phase) to operate the plant. Frame grounding was used as the primary means to ground equipment and metal electrical enclosures. Circuit breakers were used to provide overload protection.
Approximately 2 to 3 weeks prior to the accident, Willie Roberson, laborer, reported to Timothy Dupree, electrician, that he had observed electrical arcing between an abandoned electrical conduit and the frame of the No.2 conveyor near the trash metal magnet. According to Dupree, about 10 days prior to the accident, he had also observed arcing in this general area. It was raining at the time. Dupree investigated the source of the arcing and found that a bare wire was touching the conduit, which he subsequently taped. He did not, however, conduct a ground continuity test to determine why the arcing had not tripped a circuit breaker.
During its accident investigation, MSHA also found a ground fault
inside the electrical disconnect box which was used as a junction
box that supplied power (480 volts-3 phase) to the No.2 conveyor.
The junction box was located on the frame of the primary
crusher, in the area of the primary discharge conveyor head
pulley, 5 feet from ground level. The junction box contained
three, 3-phase conductors. Each conductor connection was
insulated with rubber and plastic tape. One of the phase
conductors was positioned against the backside of the junction
box. Vibration had caused the insulation to wear through,
causing a fault current. The junction box was not adequately
grounded and, as a result, the fault current energized the metal
walkway outside the crusher control booth.
DESCRIPTION OF THE ACCIDENT
David McNaught reported for work at 6:30 a.m., his normal starting time. As part of the regular work practice, every 2 hours McNaught was to alternate the primary crushing duties with Willie Roberson, laborer. At approximately 11:00 a.m., McNaught and Roberson had just switched duties, with McNaught operating the primary crusher.
Roberson was standing on the ground, near the No. 1 conveyor, when he noticed that the crusher feeder was jammed. Thinking that something was wrong, he walked up to the crusher control booth where he found McNaught laying on the walkway with his left leg over the midrail. Roberson used two fingers to check McNaught's carotid artery for a pulse; none was found. He then went to get help. Roberson located DuPree and told him that McNaught was badly injured. DuPree and Roberson then proceeded to the accident site where Dupree also checked McNaught for vital signs, finding none. Dupree then went to the quarry office and called the Clifton Fire Rescue Squad, then ran back to the accident scene.
Anthony Ferri, truckdriver, was backing his truck up the ramp to dump into the crusher feeder when he saw Dupree running toward the crusher. Ferri jumped out of his vehicle and hurried down the ramp to meet Dupree. Dupree told Ferri that McNaught was hurt and they both went to assist him.
When Ferri started to move McNaught's leg off of the midrail, he received a severe electrical shock. Ferri yelled to Dupree "I'm getting shocked." Dupree told Ferri to let go and get away. Ferri replied, "I can't." Dupree then grabbed Ferri's clothing and pulled him away. Dupree stated that when he pulled on Ferri, he received a mild shock. Dupree told Ferri not to move. He then shut off the generator eliminating all electrical power to the plant.
At 11:38 a.m., the Clifton New Jersey Police arrived and started
CPR on McNaught. At 11:41 a.m., the Clifton New Jersey Fire
Rescue Squad arrived. They continued to perform CPR on McNaught
and transported him and Ferri, in separate units, to St. Joseph
Hospital, Paterson, New Jersey. McNaught was pronounced dead on
arrival. Ferri was treated and released. The State of New
Jersey Medical Examiner's report indicated the cause of
McNaught's death was electrocution.
The primary cause of the accident was the lack of an adequate
ground on the junction box providing electrical power to the No.
2 conveyor. A contributing factor was an electrical fault which
occurred within this box. When the electrical fault occurred,
the grounding protection was not sufficient to trip the circuit
breaker controlling electrical power to the box. As a result,
the fault current energized the metal structure of the walkway on
which McNaught was standing. Although there were no eyewitnesses
to the accident, evidence indicated that McNaught was
electrocuted when he attempted to move the water pipe (which
acted as a ground) away from the handrail on the energized
walkway. This provided a path for the fault current to travel
through McNaught's body.
Order No. 4426509 was issued under the provisions of the Act of 1977 103(k) on 12/8/95:
An accident, caused by a possible exectrocution, occurred at the area of the primary crusher/feeder, on the walkway adjacent to the feed hopper bin leading to the crusher control booth, from the truck ramp. This order prohibits the use of any electrical power, supplied or generated to the plant until the source or cause of the accident can be determined.
This order was terminated on 12/14/95, after completion of the accident investigation.
Citation No. 4426517 was issued under the provisions of Section 104(d)1 on 12/8/95, for a violation of 30 CFR 56.12025:
A fatal accident occurred at this operation on 12/ 8/ 95, when the crusher operator was electrocuted due to a phase to ground fault inside a disconnect box which served as a junction box. The box provided power (480 volts-3 phase) to the No.2 conveyor and was located on the primary crusher frame. The taped insulation on a power conductor inside the box had worn through which energized the metal walkway on which the crusher operator was standing. The metal box enclosing the circuit was not grounded. This violation is an unwarrantable failure to comply with a mandatory safety standard.
This citation was terminated on 2/28/96, after the electrical contractor had removed all preexisting wiring, and will replace with new up-dated systems. The company/contractor will conduct a continuity and resistance test of the grounding system prior to start up, and the results shall be forwarded to the Manchester, NH field office, and Wyomissing, PA field office.
Citation No. 4426518 was issued under the provisions of Section 104(a) on 12/8/95, for a violation of 30 CFR 56.12030:
A fatal accident occurred at this operation on 12/8/95, when the crusher operator was electrocuted due to a phase to ground fault inside a disconnect box which served as a junction box. The box provided power (480 volts-3 phase) to the No. 2-conveyor and was located on the primary crusher frame. The taped insulation on a power conductor inside the box had worn through which energized the metal walkway on which the crusher operator was standing.
Arcing, due to the worn insulation, has occurred several weeks prior to the accident. The company had attempted to find the fault but continued to operate the plant.
This order was terminated on 2/8/96, after the hazard no longer existed. The electrical contractor had removed all preexisting wiring, and will replace with new updated systems. The company will conduct a continuity and resistance test of the grounding system prior to start up, and the results shall be forwarded to the Manchester, NH field office and Wyomissing, PA field office.
Respectfully submitted by:
/s/ Carl W. Liddeke
Supervisory Mine Safety and health Inspector
/s/ Carl A. Onder
Mine Safety and Health Inspector
/s/ Gustave E. Paul
Mine Safety and Health Inspector (Electrical)
James R. Petrie
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