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Engine · 1,595 questions

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 1,101–1,200 of 1,595 · page 12 of 16

  1. #1102 Which of the following devices would be forbidden to use as a primary means of electrical isolation?
  2. #1103 Before electrical work can be safely undertaken, the equipment must be de-energized, locked and tagged out, and verification must be made that the cir...
  3. #1104 With all other factors considered equal (such as voltage, conducting path through the body and the duration of contact), contact with an energized ele...
  4. #1105 At a minimum threshold, how many milliamps of current through the body produces a condition where most people would suffer ventricular fibrillation an...
  5. #1106 At a minimum threshold, how many milliamps of current through the body produces a condition where most people would experience respiratory paralysis a...
  6. #1107 At a minimum threshold, how many milliamps of current through the body produces a condition where most people would be unable to let go of the energiz...
  7. #1108 After prior isolation and lockout/tagout procedures are performed, which electrical device requires discharging any stored electrical energy before an...
  8. #1109 At a minimum threshold, how many milliamps of current through the body produces a painful sensation that most people would perceive as an electric sho...
  9. #1110 In figure "B" of the illustrated circuit, if the resistance of R1 is 10 ohms, R2 is 10 ohms, and R3 is 10 ohms, what is the total resistance? Illustra... illustration
  10. #1111 What would be the terminal voltage and ampere-hour capacity of the battery bank illustrated if each battery was rated at 75 ampere-hours and 12 volts?... illustration
  11. #1112 What would be the total current in figure "A" of the circuit illustrated if the value of capacitor C1 was 100 microfarads, capacitor C2 was 200 microf... illustration
  12. #1113 What will be the resulting total current if a voltage of 125 VDC is applied to the loads of the circuit in figure "A" of the illustration where the re... illustration
  13. #1114 As shown in figure "B" of the illustration, if the source voltage at the branch circuit breaker is 220 VAC, what would be the applied voltage to the l... illustration
  14. #1115 The turns ratio of the step down transformer with dual voltage secondary shown in figure "B" of the illustration is two to one (total). If 220 volts w... illustration
  15. #1116 What is the maximum current allowed to be drawn from the secondary of a 2 kVA step- down transformer with a turns ratio of four to one if connected ac...
  16. #1117 A 440/110 V single phase transformer supplies a load of 5 kW at 0.8 power factor load. What will be its primary current?
  17. #1118 A 440/110 V single phase transformer supplies a load of 5 kW at 0.8 power factor load. What will be its secondary current ignoring transformer power l...
  18. #1119 An AC motor is started and produces 25 horsepower when running at rated speed and load. Neglecting power factor considerations, how much will the kW m...
  19. #1120 The apparent power supplied to a motor is six kilovoltamps at 120 volts. What is the impedance of the motor?
  20. #1121 An electrical component is connected across a 120 volt 60 hertz AC supply. What is the current drawn by the component if the impedance is 200 ohms?
  21. #1122 If a 6-pole motor is supplied at 60 Hz and runs with a slip of 5%, what is the actual rotor speed? SB0081
  22. #1123 If the values of C1 and R1 shown in the illustration were 1 microfarad and 3 megohms respectively, which of the listed intervals of time would equal o... illustration
  23. #1124 What will be the resulting current when a voltage of 12 VDC is applied to a capacitance of 470 microfarads in figure "C" of the illustrated circuit af... illustration
  24. #1125 What does the symbol labeled "OL" represent as shown in the power circuit on lines T1 and T3 to the motor as shown in figure "A" of the illustration?... illustration
  25. #1126 Which figure represents the schematic symbol shown in figure "2"? EL-0034 illustration
  26. #1127 As shown in the illustrated devices and symbols, which of the symbols represents a standard normally closed relay contact? EL-0005 illustration
  27. #1128 In electrical circuit schematics, a normally open pressure switch is represented by which of the symbols shown in the illustration? EL-0059 illustration
  28. #1129 0. Which of the electronic schematic symbols represents the capacitor illustrated in figure 1 of the illustration? EL-0015 illustration
  29. #1130 As shown in figure "6" of the illustration, what does the symbol represent as used in electrical drawings? EL-0026 illustration
  30. #1131 The clamp-on AC ammeter consists essentially of a split-core and a rectifier-type instrument connected to the secondary winding of a particular type o...
  31. #1132 To properly use a clamp-on-type ammeter to check current flow, what must be done FIRST?
  32. #1133 How should the shunt used in an ammeter be connected?
  33. #1134 Why are external shunts sometimes used with ammeters?
  34. #1135 What is an ammeter used to measure?
  35. #1136 When a resistor is used as a shunt and is connected in parallel with a meter movement coil, what capability does this provide?
  36. #1137 Which of the following electric meter movements uses a stationary permanent magnet and movable coil?
  37. #1138 To limit the current flow through a DC voltmeter to as low a value as possible, what is the moving coil circuit provided with?
  38. #1139 What is the instrument called a galvanometer used to measure?
  39. #1140 How is a wattmeter electrically connected in a circuit?
  40. #1141 In testing a hand cranked megger prior to use, what statement is true?
  41. #1142 Prior to using an analog multimeter set up as an ohmmeter, the leads are purposely shorted together. Which of the following actions should be taken if...
  42. #1143 While troubleshooting a circuit in an engine room central control console, a resistor is suspected of being faulty. Which of the following precautions...
  43. #1144 If you disconnect and arrange both ends of a conductor of a multi-conductor cable without any contact between the individual conductors, what would a...
  44. #1145 Which of the listed statements is correct when using an digital multimeter set up as an ohmmeter?
  45. #1146 When testing a capacitor with an digital multimeter set up as an ohmmeter, what would be the indication on the display when testing an initially disch...
  46. #1147 A digital multimeter, set up as a milliammeter on the 100 milliamp scale, is known to have an accuracy of plus or minus 2%. A display reading of 10.0...
  47. #1148 If a digital multimeter set up to measure AC volts reads slightly above 'zero' when its leads are disconnected, what is this a result of?
  48. #1149 Under what circumstance would a hand-held portable phase sequence indicator be used should the main switchboard mounted fixed phase sequence indicator...
  49. #1150 In what situation would an electrical phase sequence indicator be useful?
  50. #1151 Using the portable harmonic analyzer shown in figure "A", if the clamp-on test lead is connected as shown in figure "C" of the illustration, what is b... illustration
  51. #1152 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...
  52. #1153 What will be the freezing point of the electrolyte in a fully charged lead-acid battery as compared to a discharged battery?
  53. #1154 What should be performed as routine maintenance of lead acid batteries?
  54. #1155 Which of the processes listed occurs during the charging of a lead-acid storage battery?
  55. #1156 To test the state of charge of a nickel-cadmium battery, what should be used?
  56. #1157 Which of the problems listed will occur if a lead-acid battery is allowed to remain in a discharged condition for a long period of time?
  57. #1158 What is the standard procedure for maintaining the charge in an emergency diesel starting battery by trickle charge?
  58. #1159 Which of the substances listed should be applied to battery terminals to help prevent corrosion?
  59. #1160 What is practice is considered conducting proper storage battery maintenance?
  60. #1161 What condition associated with a lead-acid battery cell can cause the plates to partially short-out and cause the cell to fail to hold a charge.
  61. #1162 What would cause a lead-acid battery to become hotter than normal during charging?
  62. #1163 When troubleshooting a lead-acid storage battery, what is the best method for detecting a weak or dead cell?
  63. #1164 Which of the problems listed will occur if a lead-acid battery is allowed to remain in a discharged condition for a long period of time?
  64. #1165 After a black out onboard and once ships power has been restored, the engine room supply fans must be started manually. What characteristic of the ele...
  65. #1166 What is the advantage of using an auto-transformer starter?
  66. #1167 What is the advantage of using a star delta starter?
  67. #1168 If a motor is direct-on-line started with the stator winding star connected, it will only take a fraction of the starting current that it would take i...
  68. #1169 You direct the electrician to take quarterly insulation resistance reading of the ship's critical motors. What additional directions would you give to...
  69. #1170 The design Power Factor (PF) of a vessel's electrical system is generally 0.8 - 0.9. The system's greatest load is inductive. One notices a slow, grad...
  70. #1171 The electrical officer is about to check the insulation resistance. When advice should you give to him as to what temperature and or when he should ch...
  71. #1172 When testing the rotor of a synchronous motor for short circuits, a low voltage source is applied across the rotor coils through the collector rings....
  72. #1173 If a three-phase induction motor malfunctions and drops to a single-phase (one supply line open), what would be the result?
  73. #1174 What would be the most likely fault if a single-phase permanent split capacitor induction motor fails to start?
  74. #1175 In testing a three-phase delta-connected winding for an open circuit using a ohmmeter, what must be done?
  75. #1176 As shown in figure "A" of the illustration, with a digital multimeter set up as an ohmmeter, what set of readings would be consistent with an open in... illustration
  76. #1177 As shown in the illustrated diagnostic setup checking for a reversed field pole on a ten- pole synchronous motor, if a rotor is being checked after re... illustration
  77. #1178 What would happen if the centrifugal switch or relay, for cutting out the starting winding of a split-phase induction motor, failed to open while the...
  78. #1179 As shown in figure "B" of the illustration, when the DC motor in figure "A" is operating at base speed what are the armature and field characteristics... illustration
  79. #1180 How may temporary repairs to an open DC propulsion armature coil be made, allowing continued operation until permanent repairs can be made?
  80. #1181 What can insufficient brush pressure on a DC motor cause?
  81. #1182 Which of the listed colors properly describes a DC motor commutator when correct commutation is taking place?
  82. #1183 If a short circuit in the armature of a DC motor occurs what would be the result?
  83. #1184 Besides a condition of overload, what could be a cause of an open armature connection in a DC propulsion motor?
  84. #1185 An open in the armature of a DC motor is suspected, but is not found by visual inspection of the commutator. What would be the next step in troublesho...
  85. #1186 How is a short in the shunt field of a DC motor best located?
  86. #1187 Which of the listed conditions might contribute to very rapid wearing of a DC machine's commutator bars?
  87. #1188 In the illustrated motor controller, what do the contacts across terminals "3" and "4" of the control circuit represent? EL-0017 illustration
  88. #1189 As shown in the illustration, what is the purpose of the main contacts of contactor "1S"? EL-0012 illustration
  89. #1190 By what means is the rotation of a three-phase induction motor reversed?
  90. #1191 Which of the following statements is true concerning the motor controller circuit shown in the illustration? EL-0004 illustration
  91. #1192 As shown in the illustration, what type of motor and motor starter are featured? EL-0137 illustration
  92. #1193 A three-phase, induction-type motor experiences an open in one phase. Which of the listed automatic protective devices will prevent the motor from bei...
  93. #1194 Referring to figure "B" of the illustrated control circuit schematic diagram, which of the following statements is true when the motor is running in t... illustration
  94. #1195 As shown in the two-speed single winding three phase motor connection diagrams illustrated in figures "B", "C", and "D", what type of motor is shown i... illustration
  95. #1196 As shown in the illustration, using the instructions provided and Chart "A" and Table "24", what size overload relay heater would be the proper select... illustration
  96. #1197 As shown in the illustration, by what means are all the 'MS' contacts are opened and closed? EL-0073 illustration
  97. #1198 With what kind of starting equipment are most three-phase induction motors of five horsepower or less started?
  98. #1199 As shown in the illustration, what type of motor is controlled as depicted in both figure "A" and in figure "B"? EL-0144 illustration
  99. #1200 Which of the following illustrated circuit schematics provides phase failure protection for a three phase motor using load side current sensing techno... illustration
  100. #1201 Which of the following statements is true concerning the cleaning of electrical contacts?

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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