Legal Requirements
A polarizing diode is used on DC equipment: A. To prevent the machine from being operated with the cable leads reversed. B. Because it is cheap. C. To polarize any stray current which could affect the grounding system. D. To keep the surge current off the lights.
A
All of the following are required electrical devices on belts, EXCEPT: A. Belt alignment switches. B. Sequence switches. C. Slippage switches. D. Automatic fire sensors.
A
All unattended loading points where electrically driven hydraulic systems are used must utilize: A. Fire proof oil or emulsion. B. DOT approved oil. C. Standard hydraulic oil. D. Synthetic oil.
A
All ungrounded exposed power conductors and telephone wires must be equipped with: A. Suitable lightning arrestors that are properly installed and grounded. B. Ungrounded lightning arrestors. C. Guards. D. Lightning arrestors connected to a high-resistance ground.
A
An electrician is to perform work under-ground on an idle day. What must be done within three hours before the electrician can enter the mine? A. The area must be declared safe by a fire boss. B. The area must be provided with additional support. C. The ventilation must be increased. D. Nothing needs to be done on idle days when no production is scheduled.
A
Automatic circuit breaking devices or fuses of the correct type and capacity must be installed to: A. Protect equipment and circuits against overloads and short circuits. B. Enable equipment to operate under an overload condition. C. Help the conductor carry overloads. D. Reduce the heat of the equipment when an overload occurs.
A
Before any welding or cutting is performed inby the last open crosscut: a. An examination for methane must be made. b. All individuals not involved in performing the task must be withdrawn from the affected area. c. Equipment must be removed outby the last open crosscut. d. The area must be wetted down.
A
Before work is performed on any power circuit, what precaution should be taken? a. Open and lockout visible disconnects. b. Open molded case circuit breaker. c. Check for frame ground d. Notify mine management.
A
Cable couplers must be designed so that when they are uncoupled, the: A. Ground check continuity conductor is broken first and the ground conductor last. B. Ground conductor is broken first and the ground continuity conductor is broken last. C. Either the ground conductor or the ground check conductor is broken first. D. Ground conductor and the ground continuity conductor are broken simultaneously.
A
Circuits that are used to power portable or mobile three phase AC equipment must be protected against over-current by: A. Circuit breakers only. B. Circuit breakers or fuses. C. Fuses only. D. Over voltage relays.
A
Couplers used in medium or high voltage circuits must be of the: A. Three phase type and be enclosed in a full metallic shell. B. Three phase type and need not be enclosed. C. Could either be two or three phase and should be enclosed. D. Two phase type and need not be enclosed.
A
Disconnecting devices should be installed in conjunction with the circuit breaker in order to provide: A. Visual evidence that the power is disconnected. B. Protection in case the circuit breaker should fail. C. Greater over-current protection in the machine. D. Greater over-current protection in the cable.
A
Disconnecting devices used to disconnect power from trailing cables should be: A. Plainly marked and identified. B. Adjusted to protect cable against short circuits. C. Locked out when not in use. D. Within sight of the person performing the electrical work.
A
How long can insulated power wires remain on insulated J hooks? A. 6 months. B. Insulated power wires cannot be placed on insulated J hooks. C. 1 year. D. Permanently, as long as the cable has not been damaged or is not in danger of being damaged.
A
How often must fire extinguishers be examined? A. At least once every six months. B. At least twice every year. C. At least once every year. D. At least once every month.
A
If insulated wires other than cables are used, the entry holes to metal frames: A. Must have insulated bushings to protect the wires from friction. B. Need not be bushed for small power wires. C. Need not have bushings since there is no friction at this point. D. Need not be bushed.
A
If the power conductor is smaller than No. 6 AWG, the cross-sectional area of the grounding, must be: a. Equal to that of the power conductor. b. One-half the size of the power conductor. c. Larger that the power conductor d. Three-fourths the size of the power conductor.
A
One circuit breaker used to protect two or more branch circuits: A. Must provide over-current protection for the smallest conductor B. Must provide over-voltage protection for both conductors. C. Must provide over-voltage protection for the smaller conductor. D. Must provide over-current protection for the largest conductor.
A
Protection devices that do not meet NEC requirements would: A. Not be considered adequate under the law. B. Probably be safe to use only underground. C. Probably be safe to use only on the surface. D. Probably still be adequate under th law. E. Probably be safe to use in most situations.
A
Sheaths, armors, and conduits which are made of metal and which enclose power conductors: a. Must be grounded because it is the law and also for safety reasons. b. Need not be grounded. c. Should be grounded when required by the mine operator d. Should be grounded when required by an electrician supervisor.
A
The cross-sectional area of any grounding wire must be at least: A. One-half the cross-sectional area of the power conductor. B. One-forth the cross-sectional area of the power conductor. C. Three-fourths the cross-sectional area of the power conductor. D. Three-fifths the cross-sectional area of the power conductor.
A
The current-carrying capacity of a conductor found in an underground mine must be deter-mined by the standards set by the: A. National Electric Code. B. UMWA Safety Committee. C. Underwriter's Laboratory. D. State Mine Law.
A
The fence surrounding all surface transformer installations should be at least: a. 6-feet high. b. 8-feet high. c. 4-feet high d. 5-feet high.
A
To protect cables from damage and to prevent strain on electrical connections: A. The cable should be clamped to the machine. B. The cable should have a loosely made splice in it which will pull apart when excessive strain is exerted on the cable. C. The cable must be adequately guarded. D. The cable must be on a cable reel.
A
Underground low and medium voltage alternating current, serving portable or mobile three-phase alternating current equipment, must be protected by: A. Circuit breakers. B. Dual element fuses. C. Fuses D. Either fuses or circuit breakers.
A
What type of resistor is provided with power-factor capacitors? A. Bleed-off resistors. B. Carbon resistors. C. Series resistors. D. Parallel resistors.
A
When a main power circuit enters the underground mine the disconnecting switch is installed: A. On the surface within 100 feet of the entry point. B. Underground. C. Either on the surface or underground. D. On the surface within 1000 feet of the entry point.
A
When changes in the electrical system are made, those changes must be made on the mine map: A. No later than the end of the workday following completion of the change. B. By the end of the month in which the change was made. C. Within three days. D. Within one week.
A
When electrical equipment is operated inby the last open crosscut, a test methane shall be taken at intervals not to exceed: a. 20 minutes. b. 15 minutes. c. 10 minutes. d. 30 minutes.
A
When insulated wires, other than cables, pass through metal frames, the holes: A. Must be substantially bushed with insulated bushings. B. Should be bushed with material other than insulation. C. Need not be bushed. D. Should be bushed only if they are power wires.
A
When underground, the disconnecting device must be located within: A. 500 feet of the bottom of the shaft or bore-hole. B. 1000 feet of the bottom of the shaft or bore-hole C. 200 feet of the bottom of the shaft or bore-hole. D. 400 feet of the bottom of the shaft or bore-hole.
A
Which of the following types of power wires need not be supported on well installed insulators and prevented from coming in contact with combustible material, roof, or ribs? A. Special high voltage cables. B. Trolley feeder wires. C. Signal wires. D. Special low voltage and medium voltage cables.
A
Which of these power wires must be supported on insulators? A. Ordinary cables to power non-mobile equipment. B. Trailing cables for mobile equipment. C. Specially designed high voltage cables to underground transformers. D. Insulated ground wires.
A
Who should make the daily inspection of ventilation fans? A. A certified electrician or competent person. B. A fire boss. C. A mine foreman. D. The superintendent.
A
All electric equipment and circuits must be protected from a short circuit by: A. Proper grounding. B. Automatic circuit breakers or fuses. C. Fuses only. D. Air switches.
B
All metallic frames, casing or enclosures of electrical equipment: a. Need not be grounded when no hazards exist b. Must be grounded to ensure no difference of potential between the equipment and c. Need not be grounded if the equipment rests on the ground. d. Should be grounded under certain circumstances.
B
All underground electrical equipment should be examined: a. During each working shift. b. Weekly c. Monthly d. Daily
B
Circuit breakers and disconnect switches that protect high voltage circuits: A. Should be labeled only to some special equipment. B. Must be labeled to show which equipment they control. C. Can be labeled for convenience. D. Need not be labeled because it is obvious which equipment they control.
B
Diode grounding can used on: a- AC machinery only. b. DC machinery with one polarity permanently grounded c. Face equipment only d. Rubber-tired dog sleds.
B
Each ungrounded, exposed power conductor that leads underground must be equipped with lightning arrestors that are located within: A. 500 feet of where the circuit enters the mine. B. 100 feet of where the circuit enters the mine. C. 400 feet of where the circuit enters the mine. D. 200 feet of where the circuit enters the mine.
B
How far from the portal must a disconnecting device that is serving a high-voltage circuit be located? a. 500 feet. b. Within 100 feet. c. 2,000 feet. d. 1,000 feet.
B
How often should automatic closing doors on main mine fans be checked? A. Once a day. B. Once a month. C. Once each six months. D. Once a week.
B
If a piece of electrical equipment has the approval plate missing, it: a. Should be taken outside to the shop within 24 hours. b. Is not permissible. c. Is permissible. d. Is still approved but a new plate should be obtained
B
If an electrician observes an electrical hazard, that electrician should first: A. Begin repairing the cable immediately. B. De-energize the circuit. C. Tag-out the machine. D. Notify the foreman or supervisor.
B
If in some special where energized power centers and portable transformers must be moved, relocation must be done under the direct supervision of a: A. Mine supervisor. B. Qualified person. C. Trained person. D. Mine operator.
B
In most instances, before power centers and portable transformers are moved they: A. Need not be de-energized. B. Must be de-energized. C. Should be de-energized only when there are hazardous conditions. D. Need not be de-energized if they are moved by electricians.
B
Incandescent lamps must be installed in weatherproof sockets when they are used: a. To illuminate all underground areas. b. In a track or belt entry or near track entries to illuminate special areas other than structures. c. In underground areas of a mine except in a track or belt entry d. For illumination in any area of a surface or underground mine.
B
Incandescent lamps powered from trolley or DC feeder circuits need not be provided with short-circuit protection, as long as the lamp is: A. Of substantial construction in a glass enclosure. B. Not more than 8 feet from the circuit. C. Installed in an explosion-proof enclosure. D. Installed in a weather-proof socket.
B
Records of daily fan inspection must be kept for at least: A. 3 years. B. 1 year. C. 7 years. D. 5 years.
B
The panic bar or lever on self-propelled electric face equipment, which actuates the emergency stop switch, must extend a sufficient distance in each direction to permit: A. An increase in power. B. A quick de-energization of tramming motors. C. A reduction in power. D. A gradual de-energization of tramming motors.
B
What fire fighting equipment must be located at each temporary electrical installation of an underground coal mine? A. One portable fire extinguisher. B. One portable fire extinguisher and 240 lbs of rock dust. C. Water and 240 lbs of rock dust. D. None, if it is a temporary installation.
B
What fire suppression must be provided at all temporary electrical installations? A. One portable fire extinguishers or 240 lbs of rock dust. B. One portable fire extinguisher and 240 lbs of rock dust. C. Two pails of water and a carton of hot dogs. D. Two portable fire extinguishers.
B
What must be provided on a power unit having different sized circuit breakers? A. Different types of circuit breakers. B. Means to prevent the connection of wrong sized cable to wrong sized circuit breaker. C. Separate distribution compartments for different sized breakers D. A protective conductive mat.
B
What should be provided at storage battery charging stations to prevent the energizing the power circuits in the event of a power failure? a. Automatic disconnect switches or circuit breakers. b. Reverse current protection. c. Undervoltage release coils or undervoltage relays d. Emergency power supply
B
When adjusted to provide protection to the smallest conductor, one circuit breaker may be used to protect: A. Only two branch circuits. B. Two or more branch circuits. C. Not more than four branch circuits. D. Only one branch circuit.
B
When can one circuit breaker be used to protect two or more branch circuits? A. Two circuits cannot be connected to one circuit breaker. B. When the circuit breaker is adjusted to afford protection for the smallest conductor. C. Only when the largest conductor is protected. D. When the circuit breaker is set at maximum.
B
When electrical equipment is powered by a single-phase, 110-volt or 220-volt circuit: a. Several grounding methods can be used. b. Only one grounding method is used-a separate grounding conductor to the grounded center tap c. Grounding is unnecessary d. Can be the same grounding methods as the three-phase power circuit
B
When main power circuits enter a mine through a shaft or bore hole, the disconnecting device is installed: A. On the surface. B. Underground, within 500 feet of the bottom. C. Underground within 1000 feet of the shaft or bore hole. D. Either underground or on the surface.
B
Where should lightning arrestors be provided for underground mine phones? a. At each phone. b. At the point of entry. c. At the substation. d. 200 feet outby phones.XC
B
Which of the following is NOT true concerning movement of energized power centers and transformers? a. Energized power center and transformers must be examined prior to movement and they must be grounded during movement. b. Tower centers and transformers can never be moved while energized c. A permit is required to move energized power centers and transformers. d. Energized power centers and transformers must be moved under the supervision a qualified person.
B
Which of the following would NOT create a safety hazard when charging batteries? A. A flame safety lamp around batteries. B. Battery-box covers were lined with a flame-resistant insulating material. C. Battery trays not frame grounded while charging. D. Charging station not ventilated properly.
B
Who should change the adjustment for a circuit breaker for a continuous miner? A. The miner operator. B. An electrician. C. The foreman. D. A miner experienced in proper equipment operation.
B
All electrical equipment must be equipped with: A. Back-up lights. B. High tram. C. A frame ground. D. Rubber tires.
C
All power wires with some exceptions: A. Should be kept out of the way of workers. B. Must be insulated wherever they touch the ground. C. Will be supported on well-insulated insulators and must not contact combustible material, roof or ribs. D. Need not be specially supported.
C
Circuit breakers used in low and medium voltage AC circuits must be tested at least: A. Every three months by a qualified person. B. Once a year by an electrician. C. Once a month by a qualified person. D. Every other month by an electrician.
C
Couplers that are used with medium or high voltage circuits must be adequate for the voltage and current expected as well as being: A. Two phase. B. One phase. C. Three phase. D. Either one or three phase.
C
Disconnecting devices used to dis-connect trailing cables should be designed or equipped so that you can tell by: A. Using test equipment when power is disconnected. B. A flashlight when power is disconnected. C. Visual observation when power is disconnected. D. The sound of an alarm when the power is disconnected.
C
Electrically operated main mine fans should be equipped with all of the following EXCEPT: A. A pressure recording gauge. B. An audible warning device. C. A fan slippage alarm. D. An independent power source.
C
Frame grounds and return grounds of direct current powered equipment: A. Must be tied under the same clamp. B. Are the same leads. C. Should be separated. D. Should be cut out of all splices.
C
How often should main mine fans be checked for mechanical and electrical reliability? A. Every 6 months. B. Weekly. C. Daily. D. Monthly.
C
If a DC power system, is feeding an offtrack DC Machine, the grounded polarity of the power system: a. Cannot be used as a grounding medium. b. Can be used as grounding medium and need not be approved. c. Is an approved grounding medium fox the frame. d. Can be used for grounding only in a few situations.
C
In which one of the following may gaskets be used between two surfaces forming arresting path? a. Low-voltage switches. b. Enclosures less than 45 cubic inches. c. Headlights. d. J-boxes.
C
Insulated power cables used along belt conveyors can be suspended by insulated J-hooks for: A. As long as needed. B. 3 months. C. 6 months. D. 1 year.
C
Mobile equipment with two conductor cables and grounding diodes should be checked weekly by the following method EXCEPT: a. Reversing the incoming power to make sure that the diodes block the power to the frame. b. Passing current through the frame grounding diodes to prove the circuit is properly. c. Checking the value of the current flow through the diodes. d. With the incoming power reversed, try to start the machine to make sure that the polarizing diode is working.
C
Permanent electrical installations must be provided with at least: A. One portable fire extinguisher and 240 lbs of rock dust. B. One portable fire extinguisher. C. Two portable fire extinguishers. D. Two portable fire extinguishers and 240 lbs of rock dust.
C
Self-propelled electric face equipment that is equipped with a substantially constructed cab: A. Must be equipped with a de-energization device if used underground B. Must be equipped with a de-energization device. C. Need not be equipped with a de-energization device. D. Must be equipped with a de-energization device if used on the surface.
C
Since couplers must carry the same load as the cables with which they are used: A. They should be used only when absolutely necessary. B. Their current and voltage rating should never exceed that of the cables. C. They must be adequate for the voltage and current of the circuit. D. It is not at all practical to use couplers.
C
The entire electrical system of a mine: A. Need not be shown on a mine map. B. Should be indicated on a mine map only if it's a surface mine. C. Must be indicated on a mine map according to the law. D. Should be indicated on a mine map when deemed necessary by the operator.
C
The minimum fire fighting protection that must be provided where welding or cutting is being performed is: A. Two portable fire extinguishers. B. Rock dust and one portable fire extinguishers. C. One portable fire extinguisher and water. D. An acid soda fire extinguisher.
C
The purpose of the grounding circuit in a portable or mobile equipment circuit is to: A. Serve as a conductor. B. Be used on three-phase equipment only. C. Serve as a grounding conductor for the frames of the equipment receiving power from that circuit. D. Be used on low-,medium-voltages only.
C
Three-phase motors must be equipped with overload protection that de-energizes: A. The phase (phases) that is (are) overloaded. B. One phase when an overload occurs. C. All three phases when any phase is overloaded. D. At least two phases when there's an overload.
C
When examining fire extinguishers, the date of such examination should be recorded: A. On the mine map. B. In a special book provided by the State Department of Mines. C. On a permanent tag attached to the extinguisher. D. In the daily report kept by the mine officials.
C
When grounding, diodes, overcurrent devices, and polarizing diodes are installed on permissible equipment, they should be placed in: a. Flame-resistant compartments b. Dustproof compartments. c. Explosion-proof compartments. d. Water-proof compartments.
C
When not in use, power circuits under-ground should be deenergized on idle days and idle shifts, EXCEPT those used on: A. Trolley wire. B. Belts. C. Rectifiers and transformers. D. Ground check monitors.
C
Why must only permissible equipment be used at the face? a. To prevent dust from accumulating in the electrical components. b. To avoid the hazards of electrical shock. c. To prevent explosive gases from being ignited. d. The use of only permissible equipment is mandatory in all parts of an underground mine.
C
A de-energization device, required on self-propelled electric face equipment, is used to: A. Slowly restart the motor. B. Gradually stop the motor. C. Quickly restart the motor. D. Stop the motor immediately when necessary.
D
All circuits supplying power to underground three-phase portable or mobile equipment must contain a grounding circuit. This circuit must: a. End at the ungrounded side of the grounding resistor. b. End at the grounded side of the grounding resistor. c. Begin at the ungrounded side of the grounding resistor. d. Begin at the grounded side of the grounding resistor.
D
All single-phase loads must be connected: A. Phase-to-ground. B. In parallel-series. C. In series. D. Phase-to-phase.
D
Circuit breakers and their components and auxiliary devices: A. Need not be visually inspected. B. Need not be visually inspected if they are checked manually. C. Must be manually checked. D. Must be visually inspected.
D
Disconnecting switches or cut out switches on energized lines can be opened: A. With bare hands in most cases. B. With leather gloves. C. With bare hands only on the surface. D. Only with insulated sticks, fuse tongs, or pullers.
D
During an electrical work session, disconnecting devices should be locked out, if possible, and tagged by: A. Any certified person trained to perform electrical work. B. Any qualified person trained to perform electrical work. C. The equipment operator. D. Only the person performing the electrical work.
D
Electrical conductors should be joined together by: A. Electrical tape. B. Square knots. C. Tie wires. D. Suitable connectors.
D
High-voltage equipment in use underground, including supporting structures, must be grounded to: a. A borehole casing. b. Track. c. Metal water line. d. A high-voltage neutral.
D
The connection of lightning arrestors to the surface grounding must be located; a. No more than 25 feet from the neutral grounds entering the mine. At least 50 feet from the neutral grounds entering the mine. c. More than 50 feet from the neutral grounds entering the mine. d. At least 25 feet from the neutral grounds entering the mine.
D
The panic bar or lever on self-propelled electric face equipment must be reachable from: A. Both right and left sides of the equipment. B. The left side of the equipment. C. The right side of the equipment. D. All locations from which the equipment can be operated.
D
Underground power circuits must: A. Remain energized unless they are not in use more than two hours. B. Be energized during shift changes and down time. C. Remain energized at all times. D. Be de-energized on idle days and idle shifts
D
What type of controls are required for belt conveyors used to transport people? A. Switches every 500 feet. B. Switches every 1000 feet. C. Switches every 200 feet. D. Continuous controls.
D
When telephone wires cross over or under power lines, they must: A. Be twisted together to prevent an inductive build-up. B. Be grounded. C. Telephone wires are not permitted to cross power lines. D. Be properly insulated.
D
Where should cross bonds be placed? a. Not more than 300 feet apart. b. Not more than 2,000 feet apart. c. Not more than 500 feet apart. d. Not more than 200 feet apart.
D
B
From the following charts listed in the Code of Federal Regulation, what would be the maximum allowable circuit setting that could be used for providing short-circuit protection using a No. 6 AWG single conductor? A. 85 B. 300 C. 70 D. 65
