Petition - Docket No. 2000-116-C | Mine Safety and Health Administration (MSHA)

Petition for Modification

In the matter of
San Juan Coal Company

San Juan South Underground Mine
I.D. No. 29-02170

San Juan Deep Mine
I.D. No. 29-02201
Docket No. M-2000-116-C
30 CFR 75.1002

PROPOSED DECISION AND ORDER

On July 24, 2000, a petition was filed seeking a modification of the application of 30 CFR 75.1002 to Petitioner's San Juan South Underground Mine and San Juan Deep Mine, both located in San Juan County, New Mexico. The two separate legal identity numbers reflected that the initial development for this new operation is from two separate portals which would not be connected for several months, at which time one of the legal identity numbers would be abandoned and any and all citation and accident history consolidated under the remaining legal identity. On October 1, 2001, the Petitioner notified the Administrator for Coal Mine Safety and Health that the requested modification would not be needed for San Juan Deep Mine (I.D. No. 29-02201) because that is the inspection entity which will soon be abandoned and the mine will continue to operate under the San Juan South Underground Mine name and legal identity notice. The Petitioner alleges that the alternative method proposed in the petition will at all times guarantee no less than the same measure of protection afforded by the standard.

MSHA personnel conducted an investigation of the petition and filed a report of their findings and recommendations with the Administrator for Coal Mine Safety and Health. After a careful review of the entire record, including the petition, MSHA's investigative report and recommendations, this Proposed Decision and Order (PDO) is issued.

Finding of Fact and Conclusion of Law

The alternative method proposed by the Petitioner (as amended by the recommendations of MSHA) will at all times guarantee no less than the same measure of protection afforded the miners under 30 CFR 75.1002.

On the basis of the petition and the findings of MSHA's investigation, San Juan Coal Company, is granted a modification of the application of 30 CFR 75.1002 to its San Juan South Underground Mine and the modification is dismissed as it applies to the San Juan Deep Mine.

ORDER

Wherefore, pursuant to the authority delegated by the Secretary of Labor to the Administrator for Coal Mine Safety and Health, and pursuant to Section 101(c) of the Federal Mine Safety and Health Act of 1977, 30 U.S.C., sec. 811(c), it is ordered that San Juan Coal Company's Petition for Modification of the application of 30 CFR 75.1002 is hereby:

DISMISSED, for the San Juan Deep Mine (I.D. No. 29-02201) because a modification of the 30 CFR 75.1002 allowing the use of a high-voltage longwall system for retreat mining is not needed for the remaining mine development conducted under this mine identity.

GRANTED, for the 4,160-volt longwall located at the San Juan South Underground Mine, conditioned upon compliance with the following terms and conditions:

1. The nominal voltage of the longwall power circuits shall not exceed 4,160 volts.

2. The nominal voltage of the longwall control circuit shall not exceed 120 volts.

3. Ground-fault current for the high-voltage power circuits shall be limited by a neutral grounding resistor of 0.50 amperes or less.

4. Each high-voltage motor circuit and shearer circuit shall be provided with instantaneous ground-fault protection set at not more than 40 percent of the ground-fault current limited by the neutral grounding resistor or not more than 0.125 ampere, whichever is less.

5. The high-voltage circuit(s) supplying power from the longwall power center to the high-voltage longwall controller shall be provided with ground-fault protection set at not more than 40 percent of the ground-fault current limited by the neutral grounding resistor or not more than 0.125 ampere, whichever is less.

Where two or more high-voltage cables are used to supply power to a common bus in the high-voltage longwall controller and each cable has a ground-fault relay, each individual relay shall be set at appropriate values based on the number of relays. A time delay may be permitted for coordination with the downstream ground-fault protection devices. The time delay shall be set at the lowest practical value that permits reliable coordination; however, in no case shall the time delay exceed 0.25 seconds.

6. The longwall high-voltage power center shall be provided with backup ground-fault protection that shall deenergize the primary of the transformer in the longwall power center if a ground-fault occurs with the neutral grounding resistor open. This protection shall be set at 40 percent of the maximum voltage that could appear across the neutral ground resistor if a ground-fault occurs. A time delay for coordination with downstream ground-fault protection devices shall be set at the lowest practical value that permits reliable coordination; however, in no case shall the time delay exceed 0.25 seconds.

7. The high-voltage neutral grounding resistor shall be provided with protection that will deenergize the longwall power center if the grounding resistor is subjected to a sustained ground-fault. The protection shall not be dependent upon control power and may consist of either a thermal protection or a current transformer and overcurrent relay in the grounding resistor circuit that will deenergize the incoming high-voltage circuit supplying the power center.

8. Each high-voltage motor and shearer circuit shall be provided with instantaneous short-circuit protection by means of automatic circuit interrupting device set at not more than the setting specified in the longwall approval documentation or 75 percent of the minimum phase-to-phase short-circuit current available at the motor terminals, whichever is less. A time delay of not more that 0.050 second may be permitted for motors with high inrush currents. All components that provide short-circuit protection shall have sufficient interrupting rating to safely interrupt the maximum calculated available fault current.

9. Each 4,160-volt circuit supplying power from the longwall power center to the high-voltage longwall controller shall be provided with short-circuit protection by means of a high-voltage circuit breaker in the longwall power center. This circuit breaker shall be set at not more than 75 percent of the minimum available phase-to-phase short-circuit current at the high-voltage starter enclosure or the setting specified in the longwall approval documentation, whichever is less. All components that provide short-circuit protection shall have sufficient interrupting rating to safely interrupt the maximum calculated available fault current.

Where two or more high-voltage cables are used to supply power to a common bus in the high-voltage longwall controller and each cable has an overcurrent relay, each individual relay shall be set at appropriate values based on the number of relays. A time delay may be permitted for coordination with downstream short-circuit protection devices. The time delay shall not exceed the setting specified in the approval documentation, or 0.25 seconds, whichever is less.

10. The grounding circuit between each power center and a high-voltage longwall controller shall be monitored by a MSHA-accepted ground-wire monitoring system. When two high-voltage cables are used to supply power to a common bus in the longwall controller, each cable shall be provided with an MSHA accepted ground-wire monitoring system. The ground-wire monitoring circuits shall deenergize both cable(s) when either the grounding circuit or ground-wire monitoring circuit of either cable becomes severed or open. One circuit breaker shall be used in the power center to protect all cables connected to a common bus in the longwall controller. The cables shall be interlocked such that the circuit breaker will open when any cable is disconnected.

11. Each ground-fault current device shall be provided with a test circuit to test the device at 50 percent or less of the current rating of the grounding resistor and the test circuit shall cause the corresponding circuit interrupting device to open. Each ground-fault device shall be driven by a single window current transformer, which shall encircle the load power conductors of each circuit. The test circuit shall not subject the equipment to an actual phase-to-ground fault.

12. The longwall power center shall be equipped with a primary visible disconnecting device installed to deenergize the primary of the high-voltage transformer(s) when the device is open. A visible disconnecting device shall also be provided for the control and communications circuits.

13. The longwall power center shall be equipped with a secondary (4,160-volt) disconnecting device installed to deenergize all high-voltage power conductors extending to the longwall controller when the device is open.

14. The longwall controller shall be provided with a main visible disconnecting device installed to deenergize all high-voltage power conductors extending from the controller. The disconnecting device may be two switches mechanically connected with one operating handle.

15. Optional high-voltage disconnecting devices or cable couplers may be provided to deenergize the high-voltage cables that supply power to high-voltage components.

16. The high-voltage shearer may be provided with an optional shearer disconnect device installed to deenergize the high-voltage motor contactor compartments located on the shearer.

17. Each disconnecting device shall be installed so that:

(a) It can be determined by visual observation that the contacts are opened without removing any cover(s);

(b) All high-voltage load power conductors can be grounded when the disconnecting device is in the "open" position; and

(d) If a cable coupler is used as the disconnecting device, connect the load power conductors in the high voltage cable to the grounded frame of the enclosure by means of a grounding receptacle provided and place a dust cover on the receptacle from which the cable was disconnected.

(e) Disconnecting devices, except cable couplers and devices installed in explosion-proof enclosures, shall be capable of interrupting the full-load current of the circuit or designed and installed to cause the current to be interrupted automatically prior to the opening of the contacts of the device. Disconnecting devices installed in explosion-proof enclosures shall be maintained in accordance with the approval documentation.

A sign shall be located near the disconnecting device identifying the circuit(s) the device disconnects.

18. The control circuit for the power center shall be interlocked with the primary disconnecting device in the power center so that:

(a) When the primary disconnecting device is in the "open" position, the control circuit can only be powered through an auxiliary switch in the "test" position; and

(b) When the primary disconnecting device is in the "closed" position, the control circuit can be powered only through an auxiliary switch in the "normal" position.

19. The control circuits for high-voltage and other circuits in the longwall controller starter enclosure shall be interlocked with the main disconnecting device so that:

(a) When the main disconnecting device is in the "open" position, the control circuit can only be powered through an auxiliary control switch in the "test" position (in the test position no voltage greater than 150 volts RMS nominal shall exit the longwall controller starter enclosure); and

(b) When the main disconnecting device is in the "closed" position, the control circuit can be powered only through an auxiliary control switch in the "normal" position.

20. Each 4,160-volt cable installed as part of the longwall mining system shall be type SHD-GC or other similar cable that meets the requirements of 30 CFR 75.804, with a minimum rating of 5,000 volts, and shall have an outer jacket that has been accepted by MSHA as flame-resistant. This condition is not applicable if a separate 101(c) petition for modification for the use of other cable designs has been granted by MSHA.

21. Each splice or repair in a high-voltage cable shall be made in a workmanlike manner and in accordance with the instructions of the manufacturer of the splice or repair materials. The outer jacket of each splice or repair shall be vulcanized with flame-resistant material or made with a kit that has been accepted by MSHA as flame-resistant. Each splice or major repair shall be made so that all cable components are replaced with similar components. Repairs are considered major if there is any damage to the shielding, grounding conductors, ground-check circuit conductors, inner conductor insulation or load power conductors. Minor repairs to the cable jacket may be made by using tape accepted by MSHA as flame-resistant. Splice kits having tape as the outer jacket are not acceptable.

22. Splices and repairs in high-voltage power cables shall be made only by a qualified person (as provided in 30 CFR 75.153) who has received "hands on" training in the proper methods of splicing and repairing high-voltage cables.

23. Cable handling and support systems (for example, Bretby and monorail systems) that are designed, installed, and maintained to protect the 4,160-volt cables from damage and to minimize the possibility of miners contacting the cables shall be used.

24. High-voltage cables shall be guarded at the following locations:

(a) Where miners regularly work or travel over or under the cables;

(b) Where the cables leave the cable handling and support systems to extend to electric components; and

The guarding shall protect the cables from damage and shall minimize the possibility of miners contacting the cables. The guarding shall be of grounded metal or reinforced non-conductive flame-resistant material. Additionally, guarding shall be provided on high-voltage cables in belt conveyor entries during cleanup and belt structure removal if the cables are within 12 inches of mobile equipment, unless the cable is deenergized.

25. High-voltage cables routed along the stageloader shall be protected by grounded metal barriers.

26. Adequate means to secure the connection box or in-line connector at the middle of the face shall be installed to provide secure connection of the high-voltage cables.

27. Energized high-voltage cables shall not be handled except when the shearer cable need to be trained (shearer cable inadvertently coming out of the cable trough). When the shearer cable needs to be trained, high-voltage insulating gloves or high-voltage insulating sticks shall be used for protection against shock hazard. Miners shall not handle the shearer cable if the cable is out of the cable trough, unless the cable has been deenergized or the miner uses high-voltage gloves or a high-voltage insulating stick. Miners shall not handle any other energized high-voltage cable.

28. High-voltage personal protective equipment, including the outer protective leather and inner rubber gloves, shall be visually inspected before each use. High-voltage rubber gloves shall be field air tested before each use to ensure their effectiveness. Damaged or defective protective equipment shall be removed from the mine or destroyed. A storage facility shall be provided for the protective cable handling equipment. The storage facility location shall be clearly marked to indicate its purpose and examined weekly to ensure personal protective equipment is present. Insulated personal protective shall be rated for a minimum of 7,500 volts and electrically tested every six months in accordance with a nationally recognized standard.

29. Barriers shall be provided and covers shall be arranged so that miners can work in the 4,160-volt section of the power center without being exposed to either energized conductors or parts that exceed 150 volts RMS, including capacitors, when the primary disconnecting device is in the "open" and "grounded" position.

30. Barriers shall be provided and covers shall be arranged so that miners can work in the control compartment(s) of the power center without being exposed to either energized conductors or parts that exceed 150 volts RMS, regardless of the position of the main disconnecting device. However, the capacitance tripping circuits may remain energized.

31. Barriers shall be provided and covers shall be arranged so that miners can work in the motor contactor compartments of the longwall controller without being exposed to either energized conductors or parts that exceed nominal 150 volts RMS when the main 4,160-volt disconnecting device is in the "open" and "grounded" position.

32. Barriers shall be provided and covers shall be arranged so that miners can work in the longwall communication and control compartment(s) of the longwall controller without being exposed to either energized conductors or parts that exceed nominal 150 volts RMS regardless of the position of the main disconnecting device.

33. Barriers shall be provided and covers shall be arranged so that miners can work in the motor contactor compartments of the shearer without being exposed to any either energized conductors or parts that exceed nominal 150 volts RMS when the shearer input disconnecting device is in the "open" and "grounded" position.

34. Cover interlock switches shall be provided and maintained to automatically deenergize the incoming high-voltage circuit to the power center, longwall controller, shearer, or optional disconnect switch when any cover that provides access to energized high-voltage conductors or parts, including capacitors, is removed. However, motor junction boxes do not need cover interlock switches.

35. Caution labels shall be installed and maintained on the covers of the compartments of each longwall power center, controller enclosure, disconnect device enclosure, and shearer enclosure. The caution labels shall warn miners to deenergize and ground the high-voltage circuit supplying power to the compartment before entering the compartment. Also, caution labels shall be installed and maintained on all covers of the compartments providing access to high-voltage capacitors to warn miners against entering these compartments before all capacitors have been discharged. A means shall be available to ground the capacitors.

When low- or medium-voltage equipment or circuits can be energized with the input disconnecting device in the open position, caution labels shall be installed and maintained on the covers of the compartments to warn miners that the appropriate disconnecting device deenergizes only the high-voltage power circuit(s).

36. Before any electrical work (including testing, trouble-shooting and fault finding) is performed inside the input high-voltage compartments of the power center, longwall controller or shearer, a qualified person (as provided in 30 CFR 75.153) shall:

(a) Determine that the contacts of an outby disconnect are "open" and "grounded";

(b) Lockout and tag the disconnect; and

37. Before any electrical work (including testing, trouble-shooting, and faultfinding) is performed inside any compartment of the power center, longwall controller enclosure, or shearer containing 4,160 volts, a qualified person (as provided in 30 CFR 75.153) shall:

(a) Determine that the contacts of the appropriate disconnect device are "open" and "grounded";

(b) Lockout and tag the disconnecting device; and

Also, each ungrounded conductor or the high-voltage circuit or cable upon which work is to be performed shall be connected to the system grounding medium.

38. Before any electrical work (including testing, trouble-shooting, and faultfinding) is performed on any high-voltage equipment or cable supplied from the longwall controller, a qualified person (as provided in 30 CFR 75.153) shall:

(a) Determine that the contacts of the proper disconnecting device are "open" and all affected conductors are "grounded" or when a cable coupler is used as a disconnecting device, determine that the high-voltage cable is deenergized and disconnected for the enclosure;

(b) Lockout and tag the disconnecting device in this position; and

(c) If a cable coupler is used as the usual disconnecting device, connect the phase conductors in the high-voltage cable to a frame common to the enclosure by means of the grounding receptacle provided and place a dust cover on the receptacle from which the cable was disconnected.

39. The Petitioner's alternative method shall not be implemented until all personnel who perform maintenance on the longwall have received training in high-voltage safety and maintenance procedures. Also, all personnel who work in proximity of the high-voltage equipment or cables or who move high-voltage equipment or cables shall be trained in high-voltage safety procedures. A record of this training shall be maintained and made available to authorized MSHA representatives and to other interested parties.

40. The high-voltage longwall mining equipment shall be MSHA approved.

41. The high-voltage longwall mining equipment shall not be put into service until after MSHA has inspected the equipment and determined that it is in compliance with all the above terms and conditions. The Petitioner shall notify MSHA before mining equipment is put into service in any subsequent longwall panel. The notice shall advise MSHA of any modifications to the equipment and provide a reasonable time for MSHA to schedule an inspection of the equipment if necessary.

42. Methane monitors shall be installed and maintained on the longwall face in accordance with 30 CFR 75.342.

43. A minimum of 12 self-contained self rescuers (SCSR's) shall be stored in the vicinity of the headgate and a minimum of 12 SCSRs shall be stored along the longwall face or at the tailgate of the longwall section to meet the requirements of 30 CFR 75.1714.

44. Within 60 days after this Proposed Decision and Order becomes final, the Petitioner shall submit proposed revisions for its approved 30 CFR Part 48 training plan to the Coal Mine Safety and Health District Manager. These proposed revisions shall specify initial and refresher training regarding the terms and conditions stated in the PDO.

Any party to this section desiring a hearing on this matter must file in accordance with 30 CFR 44.14, within 30 days. The request for hearing must be filed with the Administrator for Coal Mine Safety and Health, 4015 Wilson Boulevard, Arlington, Virginia 22203. If a hearing is requested, the request shall contain a concise summary of position on the issues of fact or law desired to be raised by the party requesting the hearing, including specific objections to the proposed decision. A party other than Petitioner who has requested a hearing shall also comment upon all issues of fact or law presented in the petition, and any party to this action requesting a hearing may indicate a desired hearing site. If no request for a hearing is filed within 30 days after service thereof, the Decision and Order will become final and must be posted by the operator on the mine bulletin board at the mine.

_________________________________

Michael J. Lawless
Deputy Administrator
for Coal Mine Safety and Health