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Electricity - USCG Exam Questions

Marine electrical systems: motors and generators, switchboards and distribution, batteries, electronics, and control engineering.

Every question below is a real U.S. Coast Guard exam question with four choices. Answer one and the correct choice is revealed instantly, with the USCG reference and illustration where the question uses one.

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All Electricity questions

Questions 1,001–1,100 of 1,595 · page 11 of 16

  1. #1002 As shown in figure "A" of the illustration, the actual rudder angle repeatback signal originates at what device and is delivered to what other device?... illustration
  2. #1003 If coil 'R1-R2-R3' on the transmitter in figure "C" shown in the illustration is turned 30 degrees clockwise, how will the corresponding coils 'R1-R2-... illustration
  3. #1004 What does figure "C" of the illustration represent? EL-0092 illustration
  4. #1005 In actual applications, electrical connections associated with 'R1, R2 and R3' of the transmitter to 'R1, R2, and R3' of the indicators shown in figur... illustration
  5. #1006 What is the name of the mechanism used to transmit torque angle over distance in the illustrated rudder angle indicator system? EL-0092 illustration
  6. #1007 The electrical energy necessary to power a sound-powered telephone's small vibrating bell is obtained from what power source?
  7. #1008 What type of equipment does the wiring diagram shown in the illustration represent? EL-0093 illustration
  8. #1009 Referring to the sound-powered telephone circuit shown in the illustration, in what component are the sound-powered transmitter and receiver units loc... illustration
  9. #1010 Referring to the sound-powered telephone circuit shown in illustration, what statement is true concerning the button on the handset as represented by... illustration
  10. #1011 If overloading an electric motor becomes necessary in an emergency situation, what should be done to prevent damage to the motor while allowing sustai...
  11. #1012 What should be included in the routine periodic maintenance checks for electrical motors?
  12. #1013 When regreasing the electric motor bearing as shown in figure "B" of the illustration, what practice should be avoided? EL-0218 illustration
  13. #1014 When testing insulation resistance of electric equipment and machinery, ideally when should the insulation resistance be tested for the lowest normal...
  14. #1015 What would be the indication of a grounded switch or cable as measured by a megohmmeter?
  15. #1016 As shown in the illustrated plots of uncorrected and temperature corrected insulation resistance readings for a particular piece of equipment, at what... illustration
  16. #1017 Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out?
  17. #1018 What should you be aware of when checking the specific gravity of the battery electrolyte with a hydrometer?
  18. #1019 For accuracy purposes, which of the following devices should be used to measure the temperature of a battery electrolyte?
  19. #1020 Which of the substances listed should be applied to battery terminals to help prevent corrosion?
  20. #1021 Which of the listed battery charging circuits is used to maintain a wet-cell, lead-acid, storage battery in a fully charged state during long periods...
  21. #1022 What is the best method of determining the state of charge of a lead acid storage battery?
  22. #1023 Which of the following activities occurs during the charging process of a lead-acid storage battery?
  23. #1024 Why must caution be exercised during the charging of lead-acid storage batteries?
  24. #1025 What statement is true concerning the actual mixing process and the container used when mixing electrolyte for a lead-acid storage battery?
  25. #1026 What statement is true concerning the charging a 100 amp-hour lead-acid battery?
  26. #1027 Which of the following statements concerning Nickel-Cadmium batteries is true?
  27. #1028 You are reconnecting a three-phase induction motor to the supply line. To prevent possible damage to the load, due to the wrong direction of rotation,...
  28. #1029 What is a useful instrument for checking 3 phase A.C. motor performance by measuring possible unbalanced currents?
  29. #1030 Suppose it is desired to connect a dual voltage three phase squirrel cage induction motor for low volts, but it is undetermined whether the nine-lead... illustration
  30. #1031 Which of the conditions listed will indicate the need to clean the insulation on the windings of an electric motor?
  31. #1032 When using the test set-up shown in figure "A" of the illustration, besides the motor windings and the motor feeder cable, what circuit components are... illustration
  32. #1033 Large machines undergoing a resistance insulation testing using a megohmmeter should be discharged to remove any accumulated electrostatic/capacitive...
  33. #1034 When you are making a high potential test (megger) on the motor coils of repaired electrical machinery to ground. What would a low resistance reading...
  34. #1035 Using the temperature correction factor for the winding insulation temperature graph shown in the illustration, what would be the correction factor an... illustration
  35. #1036 Which of the listed conditions will occur if dirt and grease are allowed to accumulate between the commutator segments of a DC motor?
  36. #1037 In general, what can cause D.C. propulsion motor brush sparking to be excessive?
  37. #1038 What should be used in the cleaning of a D.C. propulsion motor's commutator face?
  38. #1039 How is the seating the brushes on a DC motor commutator first accomplished?
  39. #1040 D.C. propulsion motor brush pressure depends on the brush grade used. In practice with what device is the proper brush pressure established?
  40. #1041 With regard to the maintenance of electrical generating machines with insulated pedestal bearings, what practice should be avoided?
  41. #1042 Rotor-to-stator air gap readings should be periodically taken for electrical generation equipment. What is the best tool to use to take these measurem...
  42. #1043 If rotor-to-stator air gap readings for an electrical generating machine have changed significantly from the last reading, what should be checked?
  43. #1044 In performing routine maintenance of a ship's service alternator, what should be included?
  44. #1045 How may chattering of the collector/slip ring brushes on a generator be remedied?
  45. #1046 Which of the following materials is recommended for burnishing the slip rings of an alternator after grinding or turning?
  46. #1047 Which of the following statements, concerning the cleaning maintenance of a brushless generator, is correct?
  47. #1048 When an alternator is to remain idle for even a few days, what should be done?
  48. #1049 While inspecting the copper commutator bars of a DC generator, you notice a chocolate brown film covering the bars. What should be done?
  49. #1050 As the brushes ride on the commutator of a DC generator, eventually mica ridges will form between the bars causing sparking and chipping of the brushe...
  50. #1051 Referring to the illustration of possible brush holder mounting configurations, which figure is the correct method of configuring the brushholders on... illustration
  51. #1052 Incorrect brush pressure can result in accelerated brush wear on a DC generator. What statement concerning brush pressure is true?
  52. #1053 If a DC generator was disassembled during overhaul, it is important that the brush holder rigging be installed in the neutral plane. On larger machine...
  53. #1054 Why are electric strip heaters used in motor controllers?
  54. #1055 Before working on an electric cargo winch master switch or controller, what should be done?
  55. #1056 Which of the following methods should be used to dress the face of silver-plated contacts?
  56. #1057 The current at which a magnetic-type overload relay tends to trip may be decreased by raising the plunger further into the magnetic circuit of the rel...
  57. #1058 High pressure compressed air should not be used to clean electric motors or controller equipment. Why not?
  58. #1059 What device can be used to check the calibration of a circuit breaker?
  59. #1060 Which of the listed pairs of materials make the best insulators?
  60. #1061 As shown in figure "A" of the illustration, what phenomenon is illustrated with respect to electrical cables and ground? EL-0126 illustration
  61. #1062 When a megohmmeter is used to test insulation, what condition causes the gradual rise of the pointer reading as a result of continued cranking?
  62. #1063 When a fluorescent lamp has reached the end of its useful life, it should be replaced immediately. If not, what condition could the resultant flashing...
  63. #1064 As part of a routine maintenance program for deck machinery motor controllers, what should be done?
  64. #1065 If deck machinery is expected to be idle for an extended period of time, what should be done?
  65. #1066 If a spring-set electric solenoid-released brake on a winch fails to hold a load properly when the solenoid is de-energized, what must be done?
  66. #1067 An AC winch hoist controller such as shown in the illustration has welded contacts on the hoist contactor, and the contacts must be replaced. Before r... illustration
  67. #1068 An AC winch hoist controller such as shown in the illustration has a burned out hoist contactor coil, and the coil must be replaced. Before replacing... illustration
  68. #1069 If it becomes absolutely necessary to run an alternator at lower than 5% below its rated frequency, in terms of output voltage, what must be done?
  69. #1070 Upon loss of field excitation of a generator operating in parallel with others, what must be done?
  70. #1071 Under unusual circumstances, it may be required to operate a ship's service generator above its rated kVA. What supplemental casualty control action w...
  71. #1072 When a self-excited alternator's field has lost its residual magnetism due to a prolonged idle period, it will fail to produce a voltage. Flashing the...
  72. #1073 In the illustrated one line diagram, if the ship's service generator on line fails, what statement is true concerning the operation of the emergency d... illustration
  73. #1074 As shown in the illustrated one-line diagram of a two-tiered emergency power system for a passenger ship, what statement is true? EL-0166 illustration
  74. #1075 You are in the planning stages of replacing a battery charger, where an exact duplicate of the charger to be replaced is not available. Obviously the...
  75. #1076 According to 46 CFR, Subchapter J (Electrical Engineering), which of the following statements concerning battery installations is correct?
  76. #1077 Suppose a cargo vessel of 1600 gross tons or more is fitted with emergency storage batteries for the purpose of supplying emergency lighting and power...
  77. #1078 Suppose a cargo vessel of 1600 gross tons or more is fitted with emergency storage batteries for the purpose of supplying emergency lighting and power...
  78. #1079 In accordance with 46 CFR Part 112, a storage battery for an emergency lighting and power system must have the capacity to accomplish which of the fol...
  79. #1080 In accordance with 46 CFR, Subchapter J (Electrical Engineering), each diesel engine driven generator prime mover must have an over speed device, inde...
  80. #1081 You are in the planning stages of setting the instantaneous trip of a ship's service generator circuit breaker. According to 46 CFR, Subchapter J (Ele...
  81. #1082 There are very specific rules that govern the testing of generators found in the appropriate publication incorporated by reference. According to 46 CF...
  82. #1083 You are in the planning stages of setting the longtime over current trip of a ship's service generator circuit breaker. According to 46 CFR, Subchapte...
  83. #1084 Assuming that a ship's service generator is directly coupled to the prime mover, what condition must cause a prime mover to automatically shut down?
  84. #1085 According to 46 CFR, Subchapter J (Electrical Engineering), emergency diesel engine starting systems are required to have sufficient capacity to provi...
  85. #1086 Emergency generators are required to automatically start upon a loss of normal supply voltage, according to 46 CFR, Subchapter J (Electrical Engineeri...
  86. #1087 Emergency generators are required to automatically start upon a loss of normal supply voltage, according to 46 CFR, Subchapter J (Electrical Engineeri...
  87. #1088 According to 46 CFR, Subchapter J (Electrical Engineering), which of the following starting aids is the ONLY method allowed to ease the starting of em...
  88. #1089 According to 46 CFR, Subchapter J (Electrical Engineering), in response to a loss of normal power or a simulated test, when will the emergency loads a...
  89. #1090 According to 46 CFR, Subchapter J (Electrical engineering), regulations prohibit the use of portable electric cord or fixture wire aboard ship if that...
  90. #1091 According to 46 CFR, Subchapter J (Electrical Engineering), what statement is true concerning the use of twist-on connectors?
  91. #1092 According to CFR, Subchapter J (Electrical Engineering), which of the following statements is true concerning flexible electric cord and cable used ab...
  92. #1093 According to 46 CFR, Subchapter J (Electrical Engineering), when considering replacement, instrument and control wiring in a switchboard is to be of w...
  93. #1094 Electrical wire in general, when used aboard vessels must meet minimum requirements. Which of the following statements is/are correct?
  94. #1095 You are in the planning stages of making up a portable cable to be used for transmitting power from a battery charger on a ship to a charging receptac...
  95. #1096 It is desired to add additional 120 VAC, 100 watt lighting fixtures in the accommodations, port side fed from circuit #1 (1L110) as illustrated in the... illustration
  96. #1097 According to CFR 111.75-5, what would be the maximum amperage load on circuit #2 (2L110) of the illustrated lighting panel board L110 of the illustrat... illustration
  97. #1098 According to 46 CFR, Subchapter J (Electrical Engineering) regulations, receptacle outlets at or above what voltage are required to have grounding pol...
  98. #1099 According to 46 CFR, Subchapter J (Electrical Engineering) regulations, what is the minimum conductor size associated with a 25 or 30 ampere lighting...
  99. #1100 What is the primary means by which an electrical maintenance worker is protected from electrical hazards while performing work on an electrical circui...
  100. #1101 Which of the following voltage testers would be associated with high quality, be safe to use, and minimize the electric shock hazard?

Electricity questions: what to expect

Q How many Electricity questions are in the Engine pool?

There are 1,595 Electricity questions on this site, every one released by the U.S. Coast Guard or taken from the National Maritime Center's sample examinations, with its correct answer. The exam draws its Electricity module from the same pool.

Q What score do I need to pass the Electricity module?

Most USCG exam modules, including Electricity, require 70 percent to pass. Rules of the Road modules require 90 percent.

Q Are these the real USCG Electricity exam questions?

Yes. They are the published U.S. Coast Guard questions, matched to the National Maritime Center's 2026 sample examinations. Answer any question to see the correct choice, the USCG reference and the illustration where the question uses one.

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