DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
Metal and Nonmetal Mine Safety and Health
REPORT OF INVESTIGATION
Surface Nonmetal Mine
(Sand and Gravel)
Fatal Electrical Accident
November 29, 1999
Weber Sand and Gravel, Inc. (mine)
Weber Sand and Gravel, Inc.
Edgerton, Williams County, Ohio
Gerald D. Holeman
Supervisory Mine Safety and Health Inspector
Ronald J. Baril, Sr.
Mine Safety and Health Inspector
Stephen B. Dubina
Mine Safety and Health Administration
North Central District
515 West First Street, Room 333
Duluth, MN 55802-1302
Felix A. Quintana, District Manager
On November 29, 1999, Curtis D. Tipton, dredge operator, age 44, was fatally electrocuted when he tightened a chain clamp around an energized dredge power conductor and discharge pipe line. Tipton was in the process of clamping the rubber discharge line to a metal section of pipe when the power conductor was drawn up with the chain clamp. Tipton had a total of two years and four weeks mining experience, all at this mine, as a dredge operator. Tipton had not received training in accordance with 30 CFR Part 48.
Weber Sand and Gravel, Inc., a surface sand and gravel operation, owned and operated by Weber Sand and Gravel, Inc., was located in Edgerton, Williams County, Ohio. The principal operating official was Scott K. Blue, manager. The mine normally operated one, 10-hour shift, five and one-half days a week. Total employment was nine persons.
Sand and gravel was mined from multiple pits by dredges, pumped to shore and washed, screened, and stockpiled. The finished product was sold for use as construction aggregate or used by the company's redi-mix business in the manufacture of concrete. The last regular inspection of this operation was completed on October 16, 1998. Another regular inspection was conducted following this investigation.
DESCRIPTION OF THE ACCIDENT
On the day of the accident, Curtis D. Tipton (victim) arrived at the mine at 8:07 a.m. Approximately an hour later, after performing miscellaneous tasks, he began operating dredge No. 1. At approximately 1:15 p.m., Kevin E. Sleesman, truck driver, observed water shooting out from behind the dredge and radioed the information to Tipton. Scott K. Blue, manager, overheard the radio transmission and also observed water spraying from the dredge's pipeline.
At approximately 2:00 p.m., Blue reported that Tipton was at the scale house requesting some assistance in the repairs. Blue radioed Christopher A. Hentzell, truck driver, to assist Tipton. Hentzell and Tipton met at the shop and then proceeded to the dredge.
Hentzell reported that they tied the steel work boat between the rear of the dredge and the first float, parallel to the north side of the discharge pipe line. Work began by fitting the rubber section of discharge line to a metal pipe section. Once complete, Hentzell reported that Tipton placed a chain clamp around the rubber section of pipe line and fitted the loose end of chain to the bracket positioned on the bottom of the metal pipe.
As Hentzell began to turn the handle, the chain clamp failed to seat. Tipton hit the handle with a pipe so as to get the chain's clamping teeth to seat into the chain links and applied penetrating oil.
Hentzell reported that the chain clamp finally seated and that Tipton began to tighten the clamp. At approximately 3:00 p.m., looking away from the boat, Hentzell heard Tipton make a noise. Hentzell, thinking that Tipton had contacted the power line, attempted to push Tipton free. Unable to free him, Hentzell left the boat, straddling the pipe line to the first float. As he looked back, he reported observing arcing in several locations. He reported it was then that he realized the power line had been caught between the chain clamp and rubber line. He reported that Tipton then fell to the floor of the boat and was unresponsive to his calls.
Hentzell entered the water and swam to the next float, rested and swam to the third one. Fatigued, he climbed upon the third float and began to straddle the pipe line to the fifth float. Meanwhile, Barry Mercer, truck driver, observed Hentzell waving his arms and radioed Sleesman, reporting Hentzell's waving. Sleesman, thinking they were ready for the power to be turned on, proceeded in the direction of the dredge disconnect box. En route, Sleesman stopped and walked to the shoreline to hear Hentzell say to turn the power off. Sleesman turned the power off and returned to the water's edge to hear Hentzell say that Curt was electrocuted and to call 911. Sleesman radioed Blue for help. Blue went to the scale house and instructed Amy L. Gilbert, office clerk, to call 911. Blue then met Sleesman at the disconnect box to confirm the power was off. Blue and Sleesman then proceeded to the rescue boat. As Sleesman prepared the boat, Blue radioed Florence Township Rescue Squad for their water rescue capabilities.
When the rescue personnel arrived, Tipton was recovered by boat. It was determined nothing could be done for Tipton. Death was attributed to electrocution.
INVESTIGATION OF THE ACCIDENT
At about 4:45 p.m. on November 29, 1999, James F. Myer, mine safety manager, State of Ohio, Division of Mines and Reclamation, notified John Radomsky, mine safety and health specialist, of the accident by telephone call. An investigation began the following day and an order under the provisions of 103(k) of the Mine Act was issued to ensure the safety of the miners until the affected area of the mine could be returned to normal operations. MSHA conducted an investigation with the assistance of The State of Ohio, Division of Mines and Reclamation, and mine personnel. The miners did not request, nor have representation during the investigation.
1) The accident occurred at the electrically powered No. 1 dredge located at the east end of the north pit, in approximately 70 feet of water.
2) No. 1 dredge was a suction and chain ladder design. The dredge was powered from a 500 KVA substation. The substation consisted of three, 167 KVA pole mounted transformers connected wye - delta and were located north of the dredge near a cemetery. For each transformer, the impedance was 2.7 percent. The primary voltage was 12,470 volts, three phase, and the secondary, connected delta with one corner grounded, was energized to 480 volts, three phase. The substation was owned by North Western Electric, located in Bryan, Ohio. The phase-to-phase available fault current was 1,280 amperes, and the phase-to-ground available fault current was 1,021 amperes.
3) Electrical protection for the cable and disconnect was provided by a Westinghouse, type MA, 800 ampere molded case circuit breaker, with an instantaneous trip. The instantaneous trip unit has nine adjustable settings, these are LO, 1, 2, 3, 4, 5, 6, 7, and HI, the unit was set on No. 4. This circuit breaker was also equipped with a 120 volt shunt trip so power could be removed remotely from the dredge by someone onboard the dredge. The circuit breaker was mounted inside a Cutler Hammer enclosure, model # RLDN600, designed to hold a maximum size circuit breaker of 600 amperes and also located on a pole north of the dredge near the transformers. To provide cooling for the 800 ampere circuit breaker, a 120 volt fan was mounted inside the box and a hole was cut in the side of the box. This provided air circulation from the numerous holes in the bottom of the box. The fan was powered from a 480 volt to 120 volt single phase transformer. The dredge's electrical service was modified from 600 amp to 800 amp in approximately July 1997.
4) Testing at the Pittsburgh Safety and Health Technology Center showed the current needed to trip the No. 4 instantaneous trip settings on the 800 ampere circuit breaker was:
5) Power was provided to the dredge through 1,065 feet of cable manufactured by Rome Cable, type TC (tray cable), 3 conductor, 350 MCM copper, 600 volts. It has a type XHHW-2 insulation, which is for 90 o C. dry and wet locations. The cable was also listed as direct burial and sunlight resistant, and the internal ground wire was copper of size No. 2 (0.258 inch diameter). The cable was installed about March 21, 1997. Approximately 30 feet from the dredge, this cable spliced into four single conductors, three phase wires, and one ground wire. Each phase wire was a Pirelli Cable, type EM, 1 conductor, 350 MCM copper, 600 volts, and the insulation was rated as RHH, RHW, and USE types, which is for 75 o C dry and wet locations or underground service. The open phase conductors from the spliced cable connection were then routed along the top and side of the discharge pipe line until they reached the back of the dredge. The conductors terminated in a disconnect box on board the dredge. The ground wire was a size No. 3/0 (0.410 inch diameter) and was spliced into the ground wire in the Rome cable using a Crosby clamp. Both of these ground wires were lying on the steel pipe or on the steel structure that supported the pipe, located on a pontoon where the cable attached to the three single conductors. The ground in the Rome cable was damaged from previous overheating and only three of the seven original strands were intact, which significantly reduced the current carrying capacity. The conductors were rated for 350 amperage use.
Phase Current needed to trip CB A
7,200 amperes this phase grounded on delta
6) The dredge discharge pipe was approximately 10-7/8 inches in outside diameter. The rubber pipe section measured approximately 10-� inches at an outside diameter and was 10 feet 2 inches long. Both sections stood approximately 4 feet above the water's surface.
7) The rubber pipe was secured to the metal section by use of a No. 2 chain clamp manufactured by Black Brothers. The chain was wrapped around the circumference of the rubber pipe with a chain link fitted into the clamp's teeth. Tightening was accomplished by turning a handle over center of a threaded shaft, drawing up slack in the chain. The end of the remaining chain was then attached to a notched plate welded to the bottom of the metal pipe section. Anchoring of the remaining chain provided securing force of the metal and rubber pipe sections together.
8) The steel hull work boat, measuring 6 feet 1 inch wide, 11 feet 3 inches long, and approximately 24 inches deep, was fabricated by the mine operator. The boat was powered by a 15 horsepower Evinrude motor, model E0662742.
9) Weather on the day of the accident was cool and clear.
The primary cause of the accident was the failure to protect the phase conductor from being mechanically damaged by the chain clamp. The energized phase conductors were located in the immediate area of the work.
Order No. 7832835 was issued on November 30, 1999, under the provisions of Section 103(k) of the Act:
On November 29, 1999, a dredge operator was fatally injured at the No. 1 dredge as he and another employee were repairing the discharge pipe. The order prohibits the use of the No. 1 dredge, electrical feed, water located sump pump, and associated electrical power to these items. This order is issued to assure the safety of persons at this operation until the mine or affected area can be returned to normal mining operation as determined by an authorized representative of the Secretary. The operator shall obtain approval from an authorized representative for all actions to recover persons, equipment, and/or restore operations in the affected area.Citation No. 7801268 was issued on January 19, 2000, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR Part 56.12004:
On November 29, 1999, a dredge operator was fatally electrocuted while he and a co-worker were repairing a leak in the dredge discharge line. As the chain clamp was wrapped around the pipe line, it accidentally encircled one of the energized phase conductors located near the back side and out of view. When the victim tightened the chain clamp, it cut through the insulation of the phase conductor and the victim was shocked. The electrical phase conductors were not protected from mechanical damage.
Related Fatal Alert Bulletin:
Persons Participating in the Investigation
Weber Sand and Gravel, Inc.
Scott K. Blue, plant managerBernie's Electric Sales and Service, Inc.
Christopher A. Hentzell, truck driver
Kevin E. Sleesman, truck driver
Bernard L. Schliesser, presidentOhio Department of Natural Resources, Division of Mines and Reclamation
James F. Myer, mine safety managerMine Safety and Health Administration
Greg Plumly, mine safety inspector
Gary L. Rothwell, mine safety inspector electrical
Gerald D. Holeman, supervisory mine safety and health inspectorAPPENDIX B
Ronald J. Baril, Sr., mine safety and health inspector
Stephen B. Dubina, electronics engineer
Weber Sand and Gravel, Inc.
Scott K. Blue, plant managerKyle D. Traxler, former employee and dredge operator
Christopher A. Hentzell, truck driver
Kevin E. Sleesman, truck driver
Bernie's Electric Sales and Service, Inc.
Bernard L. Schliesser, president
Todd M. Feltz, electrician