METAL AND NONMETAL MINES
INTERPRETATION, APPLICATION AND GUIDELINES
ON ENFORCEMENT OF 30 CFR
METAL AND NONMETAL MINES
INTERPRETATION, APPLICATION AND GUIDELINES
56/57.12019 Suitable Clearance Around Stationary
This standard requires that where access is necessary, suitable clearance shall be provided at stationary electrical equipment or switch gear. The intention of this standard is to provide sufficient access and working space around such electrical equipment to insure worker safety and to avoid contact by persons with electrical components.
The standard is intended to apply to the many and varied situations that do or will exist on mine property. Among the general factors to be considered in determining "suitable clearance" are voltages and conductors (including size), insulation, guards, existing passage or working space, direction of access to electrical components, potential exposure to live or exposed electrical parts, and the grounding of live parts.
The current editions of the National Electrical Code and the National Electrical Safety Code may be used as guidance in determining "suitable clearance." The provisions of the National Electrical Code for safe work clearances around electrical equipment can be found in Article 110 ("Requirements for Electrical Installations") and Article 710 ("Over 600 Volts, Nominal, General"). Part 1 of the National Electrical Safety Code contains two sections that may be of assistance: Section 11 ("Protective Arrangements in Electrical Supply Stations") and Section 12 ("Protective Arrangements of Equipment"). The National Electrical Code may be obtained from the National Fire Protection Association, 470 Atlantic Avenue, Boston, Massachusetts 02210. The National Electrical Safety Code (also referred to as ANSI-C2) may be obtained from the Institute of Electrical and Electronics Engineers, Inc., National Bureau of Standards, 345 East 47th Street, New York, New York 10017.
Areas around stationary electrical equipment or switch gear should be restricted to authorized persons. Normal travel by or through such equipment should not be allowed unless no other travelway is available. However, if persons do travel by stationary electrical equipment, standard 56/57.11001 requires that a safe means of access be provided.
56/57.12020 Protection of Persons at
This standard requires that dry wooden platforms, insulating mats, or other electrically nonconductive material shall be kept in place at all switchboards and power-control switches where shock hazards exist. However, metal plates on which a person normally would stand and which are kept at the same potential as the grounded, metal, non-current-carrying parts of the power switches to be operated may be used.
Switchgear, regardless of voltage, which has exposed energized
parts should have insulating platforms or mats. See paragraph 3
- Low voltage (650 volts or less) switchgear which is
completely enclosed in metal enclosures does not
normally present a shock hazard if the metal enclosures
are well grounded. Metal enclosures are well grounded
if two or more good paths to ground are ground wire,
rigid steel conduit, grounded building steel, or cable
armor. Any combination of these examples which will
provide two or more good paths to ground for fault
current would eliminate the need for insulating mats at
power switches rated 650 volts or less.
- High voltage (more than 650 volts) switchgear should be
completely enclosed in grounded metal enclosures and
provided with grounded operating handles and grounded
metal plates, because of the increased hazard presented
by the higher voltages. Insulating mats or platforms
should be used where shock hazards exist, and where
physical conditions (wet, damp, and outdoor locations,
etc.) warrant their use. However, at normally dry and
well kept indoor installations (substation or switch-
gear) with grounded metal plates, insulating mats or
platforms would not provide additional protection.
- The older type switchgear, regardless of voltage rating, which has exposed energized parts should have an insulating platform or mat with an insulation rating not less than the phase-to-phase voltage of the circuit.
56/57.12028 Testing Grounding
This intent of this standard is to ensure that continuity and resistance tests of grounding systems are conducted on a specific schedule. These tests will alert the mine operator if a problem exists in the grounding system which may not allow the circuit protective devices to quickly operate when faults occur. With the exception of fixed installations, numerous fatalities and injuries have occurred due to high resistance or lack of continuity in equipment ground systems. These accident could have been prevented by proper testing and maintenance of grounding systems.
Grounding systems typically include the following:
- equipment grounding conductors - the conductors
to connect the metal frames or enclosures of electrical
equipment to the grounding electrode conductor;
- grounding electrode conductor - the conductors
connecting the grounding electrode to the equipment
grounding conductor; and
- grounding electrodes - usually driven rods connected to each other by suitable means, buried metal, or other effective methods located at the source, to provide a low resistance earth connection.
Operators shall conduct the following tests:
- Equipment grounding conductors - continuity and
resistance must be tested immediately after
installation, repair, or modification, and annually if
conductors are subjected to vibration, flexing or
- Grounding electrode conductor - continuity and
resistance must be tested immediately after
installation, repair, or modification, and annually if
conductors are subjected to vibration, flexing or
corrosive environments; and
- Grounding electrodes - resistance must be tested immediately after installation, repair, or modification, and annually thereafter.
Conductors in fixed installations, such as rigid conduit, armored cable, raceways, cable trays, etc., that are not subjected to vibrations, flexing or corrosive environments may be examined annually by visual observation to check for damage in lieu of the annual resistance test. When operators elect to conduct this visual examination as a method of compliance with 30 CFR 56/57.12028, MSHA will require that a record be maintained of the most recent annual visual examination.
The grounding conductors in trailing cables, power cables, and cords that supply power to tools and portable or mobile equipment must be tested as prescribed in the regulation. This requirement does not apply to double insulated tools or circuits protected by ground-fault-circuit interrupters that trip a 5 milli-amperes or less.
Testing of equipment grounding conductors and grounding electrode conductors is not required if a fail-safe ground wire monitor is used to continuously monitor the grounding circuit and which will cause the circuit protective devices to operate when the grounding conductor continuity is broken.
A record of the most recent resistance tests conducted must be kept and made available to the Secretary or his authorized representative upon request. When a record of testing is required by the standard, MSHA intends that the test results be recorded in resistance value in ohms.
56/57.12042 Track Bonding
This standard requires that both rails shall be bonded or welded at every joint, and rails shall be crossbonded at least every 200 feet if the track serves as a return trolley circuit. When rails are moved, replaced or broken bonds are discovered, they shall be rebonded within three working shifts.
A citation for a violation of this standard should not be issued until the end of the third working shift after rails are moved, replaced or a broken bond is discovered. That is, assuming a three shift operation, if a broken bond is discovered on a day shift, the citation shall be issued at the end of the next day shift if the broken bond is still unrepaired. A citation shall not be issued if the bond has been repaired within this period of time.
The bonding (or welding) of the rails shall be completed before any new installation of track is placed in regular or production operation. In a new area of the mine or major track installation, the bonding of both rails shall be completed in conjunction with, and progress with, the laying of rail lengths.
57.12082 Isolation of Powerlines
This standard requires that powerlines shall be well separated or insulated from waterlines, telephone lines, and air lines. Additional insulation is not required between powerlines and waterlines, telephone lines, and air lines if the insulation of the powerlines, as provided by the manufacturer, is in its original condition.
When powerlines are found to be in contact with water, telephone, or air lines, a careful check must be made of the condition of the insulation of the entire cable. If the cable contains splices, they must be vulcanized or of an equivalent type. Any insulation splits, cuts or other signs of cable abuse must be repaired in order to eliminate the possibility of "electrical tracking" and in order to make the insulating qualities of the splice or repair approximate the original dielectric quality provided by the manufacturer.
57.12084 Branch Circuit Disconnecting
This standard requires that disconnecting switches that can be opened safely under load shall be provided underground at all branch circuits extending from primary power circuits near shafts, adits, levels and boreholes.
"Branch circuit" means that portion of a wiring system extending beyond the final overcurrent device protecting the system. It follows that any circuit ahead of the branch circuit is considered a primary circuit.
Subpart L Compressed Air and Boilers
56/57.13015(b) Records of Inspections of Compressed
and Other Unfired Pressure Vessels
Section (b) of standard 56/57.13015 requires that records of inspections made by inspectors holding a valid National Board Commission shall be retained by the mine operator in accordance with the requirements of the National Board Inspection Code (progressive record - no limit on retention time) and shall be made available to the Secretary or his authorized representative.
The recordkeeping requirement may be satisfied by an operator's written statement that the inspections have been made in accordance with the incorporated code. MSHA will accept such a certifying statement annually, without regard to format, if it is made available at the time of inspection.
56/57.13021 High Pressure Hose
This standard requires the use of safety chains or other suitable locking devices at certain high-pressure hose-to-hose or hose-to- machine connections. Quick-coupling connectors are considered to be in compliance with this standard without safety chains or other locking devices if the wire used to hold the connectors is actually in use.
56/57.13030(c) Records of Inspections and Repairs of
Section (c) of standard 56/57.13030 requires that records of inspection and repairs be retained by the mine operator in accordance with the requirements of the ASME Boiler and Pressure Vessel Code and the National Board Inspection Code (progressive records - no limit on retention time) and shall be made available to the Secretary or his authorized representative.
The recordkeeping requirement may be satisfied by an operator's written statement that the inspection and/or repairs have been made in accordance with the incorporated code. MSHA will accept such a certifying statement annually, without regard to format, if it is made available at the time of inspection.
Subpart M Machinery and Equipment
56/57.14100 Safety Defects: Examination, Correction, and
This standard applies to all off-road and on-road self-propelled equipment used on mine property, including vehicles such as vans, suburbans, and pick-up trucks that are used at mine sites and remain on mine property. In most instances, it does not apply to vehicles used to transport persons between locations off mine property to mine property; however, if such vehicles transport personnel on mine property (e.g., from the gate to various sites at the mine), then such equipment must be inspected.
This standard will not be cited when an audible warning device has been installed on heavy duty mobile equipment at surface mines and surface operations of underground mines, but is inoperative because of electrical or mechanical defect.
Standard .14132 shall be used when the equipment has not been equipped with audible warning devices, or when they have been so equipped, and the device is not operational for whatever reason.
In some cases, mine operators have installed audible reverse alarms on underground equipment because prevailing conditions have dictated the need for a warning device to ensure miner safety. In this instance, Standard .14100 can be considered if the alarm is inoperable or inaudible and the defect can be shown to affect the safety of workers in the area. Surrounding noise levels, confined work areas, and distracting work assignments shall be considered at the time.
Subsection (a) is divided into three parts. Part (1) of this subsection sets a minimum performance standard for service brake systems on self-propelled mobile equipment. Part (2) sets a minimum performance standard for parking brakes on self-propelled mobile equipment. Part (3) sets a maintenance standard for all braking systems on self-propelled mobile equipment.
Standard 56/57.14101(a)(1) should be cited if a service brake system is not capable of stopping and holding the equipment with its typical load on the maximum grade it travels.
Standard 56/57.14101(a)(2) should be cited if the parking brakes are not capable of holding the equipment with its typical load on the maximum grade it travels.
Standard 56/57.14101(a)(3) should be cited if a component or portion of any braking system on the equipment is not maintained in functional condition even though the braking system is in compliance with (1) and/or (2) above. It is important to note that if a component or portion of either system renders the equipment incapable of stopping or holding itself with its typical load on the maximum grade it travels, the appropriate standard, 56/57.14101(a)(1) or (2), should be cited.
Separate citations or orders should be issued if violations of 56/57.14101(a)(1) and 56/57.14101(a)(2) are found on the same piece of equipment.
56/57.14107 Moving Machine Parts
All moving parts identified under this standard are to be guarded with adequately constructed, installed and maintained guards to provide the required protection. The use of chains to rail off walkways and travelways near moving machine parts, with or without the posting of warning signs in lieu of guards, is not in compliance with this standard.
Conveyor belt rollers are not to be construed as "similar exposed moving machine parts" under the standard and cannot be cited for the absence of guards and violation of this standard where skirt boards exist along the belt. However, inspectors should recognize the accident potential, bring the hazard to the attention of the mine operators, and recommend appropriate safeguards to prevent injuries.
This standard is to be cited when a guard at conveyor locations does not extend a distance sufficient to prevent any parts of a person from accidentally getting behind the guard and becoming caught, or in those instances when there is no guard at the conveyor-drive, conveyor-head, conveyor-tail, or conveyor take-up pulleys.
56/57.14109 Unguarded Conveyors With Adjacent
Sections 56/57.14109 require unguarded conveyors next to travel-ways to be equipped with emergency stop devices or railings. A travelway is defined in 30 CFR §§ 56/57.2 as a passage, walk or way regularly used and designated for persons to go from one place to another. If an unguarded conveyor has travelways on each side of it, both unguarded sides must be equipped with emergency stop devices or railings.
Under Sections 56/57.14109(a), emergency stop devices must be located so that a person falling on or against the conveyor can readily deactivate the conveyor drive motor. MSHA expects that a miner would be able to readily reach the emergency stop device to activate it and that the device would be located along the portion of the unguarded conveyor that is adjacent to a travelway.
Under Sections 56/57.14109(b), railings must: (1) be positioned to prevent persons from falling on or against the conveyor; (2) withstand the vibration, shock, and wear to which it will be subjected during normal operation; and (3) be constructed and maintained so that it will not create a hazard. MSHA expects that railings would be located along the portion of the unguarded conveyor that is adjacent to a travelway.
Neither the conveyor installation nor its framework is considered a railing for the purpose of these standards irrespective of its height or conformance with standard railing heights.
Sections 56/57.14109 do not apply to unguarded conveyors which are not next to travelways, including overhead conveyors, where there is no reasonable possibility that miners will come into contact with system components (e.g., idlers, conveyor belt) of the conveyor.
56/57.14130 and 56/57.14131 Providing, Maintaining,
Wearing Seat Belts
In an effort to reduce the severity of powered haulage accidents, district managers shall carefully consider the gravity and negligence of citations and orders issued for the failure to provide, maintain, or wear seat belts.
Gravity: The failure to provide, maintain, or wear seat belts is a serious safety hazard and under most circumstances should be a significant and substantial violation. Without mitigating circumstances, the gravity evaluation of reasonably likely or highly likely, and fatal would usually be justified.
Negligence: The failure to provide seat belts as required by the regulations may be considered highly negligent and therefore be the basis for a 104(d) citation/order in the absence of mitigating circumstances.
Failure to maintain seat belts in functional condition may be considered less negligent than the failure to provide seat belts.
Some factors that could increase the degree of negligence are if the defect has been reported on a preshift examination, the defect is obvious, or the defect has existed for a long period of time. The examination of seat belts for defects is required by 30 CFR 56/57.14100.
Negligence for failure to wear seat belts should be determined by
the extent of the mine operator's efforts to enforce the seat
belt requirement. Examples of such efforts may include:
- evidence that the equipment operators are instructed on
the mandatory use of seat belts;
- regular observation by supervisors to determine whether
seat belts are being worn;
- corrective action taken by supervisors when seat belts
are not being worn; and
- the development and implementation of a job safety analysis program to reinforce task training for equipment operators.
If the mine operator does not make any effort to ensure that seat belts are worn, the negligence would be high and a 104(d) citation/order would be appropriate. If, however, the mine operator's conduct indicated an effort to have seat belts worn, the negligence would usually be less than high.
Special Assessment: All citations/orders issued for failure
provide, maintain, or wear seat belts should be reviewed for
special assessment. The types of violations that meet the
requirements for special assessments are:
- violations cited as contributing to a serious injury or
- violations cited as an unwarrantable failure;
- violations cited as an imminent danger; or
- violations evaluated as having extraordinarily high gravity (highly likely and fatal).
56/57.14132(a) and (b) Horns and Backup Alarms For
Standard 56/57.14132(a) sets a maintenance standard for manually operated horns or other audible warning devices that are provided as safety features on self-propelled mobile equipment. The self- propelled mobile equipment referenced in this subsection includes any wheeled, skid-mounted, or track-mounted equipment capable of moving itself. This standard should be cited if any audible warning device that was provided on the equipment as a safety feature is not functional. This includes manually-operated horns, automatic reverse-activated signal alarms, wheel-mounted bell alarms and discriminating backup alarms.
Standard 56/57.14132(b) pertains only to self-propelled mobile equipment where the operator has an obstructed view to the rear. A backup alarm system is only required when there is an obstructed view to the rear and an observer has not been provided. Standard 56/57.14132(b)(1) must be cited if an observer is not present and a backup alarm system is not provided on the equipment. Standard 56/57.14132(b)(2) must be cited if an observer is not present and a backup alarm system is provided and is operating as designed (functional) but is not audible above the surrounding noise level.
56/57.14201 Conveyor Start-Up
This standard requires that no conveyor is started unless the person starting it is certain that all persons are clear. A positive audible or visible warning system is required to provide necessary flexibility to accommodate different mining and milling conditions throughout the nation. This standard has been uniformly interpreted by MSHA, and its predecessor organizations, to include both automatic and manual conveyor alarm systems as long as these systems are effected at each conveyor or series of conveyors within a system. However, MSHA and many mine operators believe that an automatic warning and start-up system is more effective than a manual system and, therefore, should be the system of preference. An automatic conveyor alarm system, or a system designed to first activate a start-up horn before the start-up system of the conveyor, is more effective in eliminating human error at the time of a conveyor start-up than a manual system.
A manual conveyor alarm system is one which actuates an audible alarm by an independent switch and uses a separate switch to actuate the conveyor. It may be considered "positive" and in compliance with the standard provided the system is capable of effectively warning persons prior to the time the conveyor will be started. Operators should be instructed to assure that persons are clear before starting the conveyor or conveyor system.
Although the standard specifies either an audible or visible warning system, visual warnings in bright sunlight or other well-lighted places are ineffective. For this reason, it is recommended that an audible warning system (horn) be used throughout a conveyor system located in bright sunlight or other well-lighted places. The duration of the audible warning shall be long enough to allow anyone who is endangered by an activated conveyor system to move to safety.
Particular attention must be given to the scope, or the overall effectiveness of the audible warning system, to be certain that the warning is effective at each and every conveyor in the system. This does not mean that a separate horn or similar device must be installed for each conveyor, but it does mean that the warning must be positive and effective for each conveyor or series of conveyors capable of being shut down or started independently within the system.
This standard specifically exempts those conveyor systems visible from the start-up switch from the requirements of a positive start-up warning system. However, MSHA recommends that all conveyor systems have a positive audible or visible start-up warning even though they are visible from the start-up switch.
56/57.14211 Blocking Equipment in Raised
Standards 56/57.14211 prohibit persons from working on, under, or from raised portions of mobile equipment or a component of mobile equipment until the equipment has been blocked or mechanically secured. The standards specifically require blocking of raised components to prevent a "free and uncontrolled descent" in the event of a sudden failure of the system holding up the raised component. Hydraulic telescoping boom cranes with flow restrictions or check valves in the hydraulic system will prevent a free and uncontrolled descent of the boom and attached work platform.
Compliance with 56/57.14211 can also be achieved by mine
operators if the following four safety features are implemented
when hoisting personnel with cranes:
- use of an anti-two-block device with automatic shutdown
capabilities that will prevent breaking of the load or
whip line in the event of a two-block condition (a horn
or light warning in lieu of automatic shutdown is not
- all running ropes, other than rotation resistant ropes,
must have a safety factor of at least 7;
- rotation-resistant ropes must have a safety factor of
at least 10; and
- the cranes used to hoist personnel must be equipped for and operated with controlled load lowering and must not be capable of being operated in "free fall."
MSHA strongly recommends that miners avoid working near or on cranes unless there is no other means of performing the task, or the other means creates a greater hazard.
56/57.14213 Ventilation for Welding
See Subpart D, Air Quality, Radiation, and Physical Agents.
Subpart N Personal Protection
56/57.15001 First Aid Materials
This standard requires that adequate first-aid materials, including stretchers and blankets, shall be provided at places convenient to all working areas, and that water or neutralizing agents shall be available where corrosive chemicals or other harmful substances are stored, handled or used.
The purpose of this mandatory standard is to ensure that adequate first-aid materials, including eye wash solution, safety showers (not just "deluge" showers, but a constant warm water supply for long-term flushing) and other neutralizing agents are available to workers where corrosive chemicals or other harmful substances are stored, handled, or used. Neutralizing agents shall be readily available for first-aid treatment and cleanup of corrosive chemical spillage or leakage. Spill-control products are commercially available for all hazardous chemical substances.
These products both absorb and neutralize hazardous chemicals, thereby reducing the hazard to workers while containing the spilled chemicals.