Week 6

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Week 6
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  1. Which OSHA standard states "temporary protective grounds shall be placed at such locations and arranged in such a manner as to prevent each employee from being exposed to hazardous differences in electrical potential.
    1910.269(n)(3)
  2. A task to stop the flow of power on a line or piece of equipment such as opening a switch or jumper.  Synonymous with de-energize.
    Kill
  3. What are the first two steps to working on lines and equipment?
    • To properly clear the line or equipment from all potential sources of energy.
    • To properly install personal protective grounds.
  4. A condition where a line or piece of equipment does not have any power flowing through it.  Synonymous with de-energized.
    Dead
  5. What are the two main objectives of personal grounding equipment?
    • Limit the amount of current flow and voltage drop across the lineworker's body.
    • Minimize the time the current can flow through the lineworker's body.
  6. A condition where a line or piece of equipment has power flowing through it.  The term that is synonymous with energized.
    Hot
  7. "If it is not grounded, it is not______."
    Dead
  8. The fundamental concept of ______ ______ ______ is to provide a path to ground for the power to flow through, bypassing the line worker.
    Personal protective grounding
  9. What is the current range that is detectable to the human body?
    1-5 milliamperes.
  10. What is the current range that is painful to the human body?
    9-15 milliamperes.
  11. What is the current range that causes the human body to instantaneously respond to the pain by letting go or moving away?
    16-100 milliamperes.
  12. What is the current range that can cause ventricular fibrillation of the heart?
    100-700 milliamperes.
  13. What is the current range that causes burning of the skin and organs?
    Greater than 1 ampere.
  14. As it pertains to the effect of current on the human body, what else contributes to the potential for injury?
    Voltage
  15. Grounding methods are designed to limit the current to a ________.
    Safe level
  16. What are the two methods of using personal protective grounds to protect line workers?
    • Bracket grounding
    • Equipotential zone grounding
  17. The personal protective grounding method that is most commonly used during large construction projects and on underground lines.
    Bracket grounding
  18. The personal protective grounding method that provides a low resistance, short-circuited connection from the line to the earth at key locations on one or both sides of the work site.
    Bracket grounding
  19. The personal protective grounding method where some current would flow through the line worker's body.
    Bracket grounding
  20. The personal protective grounding method where almost no current would flow through the line worker's body.
    Equipotential zone grounding
  21. The personal protective grounding method that provides a low resistance, short-circuited connection from the line to the earth and shunts or diverts the flow of current around the line worker.
    Equipotential zone grounding
  22. The personal protective grounding method that is typically used on wood pole lines and is applied on the structure that the line worker is working on.
    Equipotential zone grounding
  23. The personal protective grounding method that is most commonly used when only a few locations need to be worked on.  This typically occurs during maintenance of existing power delivery systems.
    Equipotential zone grounding
  24. The best method of personal protective grounding.
    Equipotential zone grounding
  25. What factors cause the resistance of the grounding source to vary?
    • Connections
    • Soil resistance
    • Neutral conductor size
    • How the grounds are installed
  26. What causes the resistance of wood poles to vary?
    • Treatment method
    • Wood species
    • Moisture content
  27. The amount of induction is somewhat proportional to what three factors?
    • The distance between the line you are working on and the source of induction
    • The line voltage
    • The amount of current flowing
  28. Other than powerlines, what are three other possible sources of induction mentioned in the book?
    • Radio
    • Television
    • Microwave towers
  29. What are the five sources of energy mentioned in this chapter that can cause the line to become accidentally energized?
    • Induced voltage
    • Lightning
    • Capacitance
    • Static charge
    • Inadvertent Energizing
  30. What are the three sources of capacitance that are encountered while working on power lines?
    Line capacitors and underground cables are the most common.  Long overhead transmission lines can also have a capacitance effect.
  31. What typically causes a static buildup in a conductor?
    Warmer winds blowing across the surface of the conductor.
  32. The amount of static charge in a conductor is dependent upon?
    • Size of the conductor
    • Length of the line
    • Wind direction
    • Temperature
  33. What are the four ways a line can become inadvertently energized mentioned in the book?
    • Inadvertent operation of a switch, breaker, disconnect, etc.
    • A mechanical failure of a switch, causing it to fall closed
    • Generator backfeed
    • Line contacts with foreign objects
  34. The amount of current that a given system can deliver to a fault or short circuit.
    Fault current
  35. The amount of current that can be delivered to a fault is largely dependant upon...
    • The impedance of the system components, which increases the farther you get from the substation, causing less availability
    • Size and type of the substation transformers
    • Size and type of the generators
  36. It is extremely important that personal protective grounds are sized to be able to carry the fault current at the location until ___________________.
    the circuit protection clears the fault
  37. A difference in potential between a worker's or a member of the public's feet when the ground is energized by fault current.
    Step potential
  38. A voltage drop or difference of potential between an energized metallic object that the employee is in contact with and the point on the earth's surface where he is standing.
    Touch potential
  39. The National Electric Safety Code requires the system neutral be grounded a minimum of _____ times per mile.
    Four
  40. This conductor can be viewed as an extension of the station ground grid.
    System neutral
  41. The selection of the best available ground sources is critical to the objectives of personal protective grounding.  What six examples does this chapter give as possible grounding points?
    • Substation ground grid
    • System neutral
    • Static/shielding wires
    • Driven ground rod
    • Anchor rods
    • Metal structures
  42. What grounding point is prohibited by some companies due to the uncertainty of what would happen to the structure should a fault occur?
    Anchor rods
  43. When using driven grounding rods, a change of temperature from 68 degrees to 23 degrees will increase the soil resistance by a factor of _____ due to freezing.
    Ten
  44. When using a metal structure as a grounding point, what must you take into consideration?
    Paint, rust, or non-conducting substances that would prevent a low-resistance connection.
  45. After de-energizing a line or equipment, what does OSHA require before personal protective grounds may be installed?
    Testing for voltage
  46. What are the most common methods of testing for voltage before applying personal protective grounds?
    • Buzz testing
    • Audible Tester
    • Neon indicator
    • Multi-range voltage detector
  47. The act of connecting a metal object to the end of a live line tool and slowly touching and pulling away from the conductor several times.  A humming noise may be heard and an arc may be seen indicating voltage is present?
    Buzz testing
  48. An electronic instrument that connects to a live-line tool.  When the tool is held near the conductor the tool will provide an audible sound and a flashing light if voltage is present.
    Audible tester
  49. An instrument that can be attached to a live-line tool.  When held near an energized conductor it will provide a clear visual indication.
    Neon indicator
  50. The tool which uses the field strength to estimate the line to line voltage of conductors. 
    Multi-range voltage detector
  51. The tool which can be used to detect the presence of voltage through capacitance test points on underground elbow connectors.
    Multi-range voltage detector
  52. For personal protective grounding on distribution circuits, what two categories of clamps are most widely used?
    • "C" clamps
    • Snap-on clamps (duckbill)
  53. For personal protective grounding on transmission circuits, what four categories of clamps are most widely used?
    • All-angle
    • "C" clamp
    • Snap-on (duckbill)
    • Tower grounding clamps
  54. The length of grounding jumpers should be kept as short as practical to minimize the ______ ______ that can occur during a fault.
    whipping effect
  55. The IEEE guide for protective grounding says the mechanical force of a jumper with a fault current range of 30,00 to 60,000 amps can reach _____ foot pounds.
    450
  56. Personal protective grounding cables must never be smaller than #___ AWG copper.
    2
  57. Cluster brackets are only used with ______ _______ grounding.
    equipotential zone 
  58. Used to effectively ground conductors that are being installed.  They are made of a roller system that is attached to the conductors that are in motion and are mounted to a housing that allows for the attachment of a grounding cable.  They are typically installed at each end of the pull section.
    Running ground
  59. Used to effectively ground conductors that are being installed.  They are installed at various locations throughout the pull section. They essentially connect to the assembly that supports the weight of the conductor as it's being pulled through.
    Stringing block grounds
  60. Grounded conductors within the equipotential zone such as down guys and phone messenger cables.
    Foreign grounds
  61. Underground splices and terminations are frequently rated as either ___ amp or ___ amp.
    • 200
    • 600
  62. A device that is inserted into a bushing to provide a contact point for a voltage detector.
    Test probe
  63. Used for isolating, testing, and grounding underground circuits.
    Portable feedthru bushing
  64. Used for grounding applications in underground systems and provide a temporary ground.  They are ussually used in conjunction with a feedthru bushing where this device is plugged into one side and the conductor into the other side.
    Grounding elbow
  65. Used for grounding applications in underground systems and bleed off capacitance.  The cable must be tested and grounded before being temporarily stored in this device.
    Grounded bushing
  66. Used to cover vacated bushings on transformers and other underground apparatus.  They insulate, shield, and seal the vacated bushings.
    Insulated protective cap
  67. Used to prove underground cable de-energized at the work location and are not used as a personal protective ground.
    Grounded spike clamp
  68. A specially designed clamp that attaches to single blade cutout switches and provides a stud for the attachment of personal protective grounds.
    Disconnect grounding clamp
  69. The smallest part of an element that contains all the properties of that element.
    Atom
  70. A material that readily allows the flow of electrical current.
    Conductor
  71. One of the three principle parts of the atom, the part that carries a negative charge.
    Electron
  72. A substance that can not chemically be broken down any farther.
    Element
  73. Magnetic lines of force.
    Flux
  74. Loosely held electrons in the outermost shell of an atom.
    Free electrons
  75. The number of times a generator rotates in a second.
    Frequency
  76. The unit of measure for frequency.
    Hertz
  77. The process by which current flows through a conductor when passed through a magnetic field.
    Magnetic induction or induction
  78. Any material that resists the flow of electrical current.
    Insulator
  79. A naturally occuring discharge of static electricity.
    Lightning
  80. A substance that possesses the property of attracting iron.
    Magnet
  81. One of the three principle parts of the atom, it has no charge.
    Neutron
  82. The positively charged mass at the center of an atom, it contains the proton and neutron and makes up most of the mass of the atom.
    Nucleus
  83. One of three principle parts of the atom, it has a positive charge.
    Proton
  84. Electrons that are sitting still and not moving.
    Static electricity
  85. The outermost electron orbit of an atom.  Electrons located in this shell determine the conductive properties of an element.
    Valance shell
  86. The measure of electromotive force.
    Volt
  87. The basic building blocks of the universe.
    Atoms
  88. A specific type of atom.
    Element
  89. Name the three principle parts of an atom according to the book, the two additional basic parts according to the lecture, and the sixth part that we will need to know for the test.
    • Proton
    • Neutron
    • Electron
    • Nucleus
    • Valence shell
    • Electron shell
  90. An electron is about ___ times larger than a proton.
    three
  91. The proton weighs about ______ times more than the electron.
    1840
  92. What is the law of charges?
    Opposite charges attract, and like charges repel.
  93. The law that states a spinning object will pull away from it's center point, and the faster it goes, the stronger the force.
    The law of centrifugal force
  94. How many electrons do good conductors generally have in their valence shell?
    one to three
  95. If the negative pole of a magnet is passed near a conductor, the free electrons will ____________.  If the positive pole of a magnet is passed near a magnet, the free electrons will ____________.
    • Move away creating current flow
    • Come rushing back
  96. What would be impossible if magnets did not exist?
    AC generation
  97. What three elements have molecular properties that allow them to be magnetized by applying an electrical current?
    • Iron
    • Nickel
    • Cobalt
  98. The basic operating principle for transformers and generators.
    Magnetic induction
  99. Electromagnetic fields around power lines vary based on what two variables?
    • Voltage
    • Current flow of the circuit
  100. Does induction work with DC circuits?
    Nope
  101. How many times does the magnetic field around a power line in the U.S. expand and collapse per second?
    60 times
  102. The theory that says electricity flows from the most negative point to the most positive point.
    The electron theory of current flow
  103. Lightning can carry up to _____ volts and between ____ and ____ amps of current.
    • a billion
    • 10,000
    • 20,000
  104. What is the average length of a lightning bolt?
    six miles
  105. What is the best method to protect a line worker against lightning.
    There is no protection from lightning, sit it out in the cab of a truck.
  106. Lightning bolts can reach upwards of ________ degrees fahrenheit.
    50,000
  107. What did Alessandro Volta invent.
    The "first" battery known as the voltaic pile.
  108. Who was Count Alessandro Volta?
    • 1745-1827
    • Como, Italy
    • Born into nobility
    • Physicist and pioneer in the study of electricity.
  109. If the strength of a magnet is increased and the speed at which it is being passed near a conductor is increased, what will happen?
    The voltage of the current will increase
  110. According to this chapter, what four factors are affected by voltage in the power system?
    • The amount of insulation needed for a given power line
    • The seperation between line conductors
    • Safe working practices
    • The type of tools needed to work on the lines.
  111. What are the four typical distribution voltages named in this chapter?
    • 7.2/12.47 kV
    • 7.6/13.2 kV
    • 12/20.8 kV
    • 19.9/34.5 kV
  112. What are the typical transmission voltages named in this chapter?
    • 69 kV
    • 115 kV
    • 138 kV
    • 230 kV
    • 500 kV
    • 765 kV
  113. On an electron, the lines of force come ______.
    Inward
  114. On a proton, the lines of force extend _______.
    Outward
  115. Lines of force on like charges never ______.
    cross
  116. Lines of force on different charges _______.
    combine
  117. How many electrons do good insulators have in their valence shell?
    Seven or eight
  118. If an element has four, five, or six electrons in it's valence shell it would be considered to be a _________.
    Semi-conductor
  119. What is the maximum number of electrons that can be in the valence shell?
    eight
  120. What is produced when electrons are bumped in and out of the valence shell?
    Heat
  121. Which would be spinning faster, an electron in the electron shell or an electron in the valence shell?
    Valence shell
  122. If a material does not need an electrical current applied to have magnetic properties it would be considered a _________ magnet.
    Permanent
  123. What are the two methods of creating induction?
    • By moving a magnetic field over a conductor.
    • A magnetic field expanding and collapsing next to a conductor.
  124. What is the fundamental concept of personal protective grounding?
    To provide a path to ground for the power to flow through bypassing the line worker.
  125. The human body is an excellent conductor because?
    • It is 70% water.
    • The central nervous system is a network of conductors.
  126. It only takes about 1/3 of an amp to put your heart into __________.
    ventricular fibrillation
  127. What is the common current value of a light bulb?
    1 amp
  128. What is the common current value of a house service?
    20 amps
  129. What is the common current value of a secondary circuit?
    250 amps
  130. What is the common current value of a primary feeder?
    400
  131. With EPZ grounding, almost no current flows through the line workers because the cluster bar is ______________. 
    closer to the earth than the line worker's feet.
  132. According to the book, fault currents have reached ______ to ______ amps.
    • 30,000
    • 40,000
  133. The substation ground grid is designed to have adequate capacity to carry _________.
    any fault current that may flow
  134. How far would the system neutral extend throughout the circuit?
    The entire length.
  135. The ground rod should be driven as deep as possible to __________.
    reduce overall resistance
  136. Which instrument used to test lines for voltage has a self test feature?
    Multi-range voltage detector
  137. A gas filled tube that glows in the presence of voltage.
    Neon indicator
  138. When introduced to induction, coiling a conductor can ______ the magnetic field and placing an iron rod inside the coil will ______ the lines of flux.
    • intensify
    • concentrate
  139. Voltage pushes, amperage _______.
    flows
  140. Voltage dictates insulation, where amperage dictates ________.
    conductor size
  141. On personal protective grounds, the size of the cable must be marked every __ feet.
    4
  142. The personal protective grounding cluster used for underground, it has exposed clamps similar to overhead grounds.
    Live front grounds
  143. Which element is the best natural conductor?
    Silver

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