Journeyman Electrician
Journeyman Electrician is a trademark of its owner, which is not affiliated with and does not endorse Test Treasure Publication or TTP Prep.
Journeyman Electrician is a trademark of its owner, which is not affiliated with and does not endorse Test Treasure Publication or TTP Prep.
10 sample questions for the Journeyman Electrician, with the correct answer and an explanation for each. No account needed. Try each one before you open the answer.
Sections covered on the exam: Electrical Theory And Calculations, Electrical Theory and Calculations, Three-Phasesystemsandtransformers, Voltagedropandconductorsizing, Nec Fundamentals, Branch Circuits, And, Requirements, Workingspaceaboutelectricalequipment, NEC Fundamentals, Branch Circuits, and Load Calculations, Requiredreceptacleoutlets, Services, Overcurrent Protection, And, Outsidebranchcircuits,Feeders,Andservices, Overcurrentprotection, Groundingelectrodesystemandconductors, Wiring Methods and Materials, Services, Overcurrent Protection, and Grounding, Wiring Methods And Materials, Generalwiringmethodrequirements, Equipment For General Use, Luminairesandappliances, Motorcircuits, Transformers, Special Occupancies, Equipment, And, Healthcareandotherspecialoccupancies, Specialequipment, Renewable,Emergency,Andfirealarmsystems, Electrical Safety And Safe Work Practices, Electrical Safety and Safe Work Practices, Shockandarcflashprotection, Equipment for General Use.
Question 1 · Electrical Theory And Calculations
A 10 Ω resistor is connected in series with a parallel group made up of a 20 Ω resistor and a 30 Ω resistor. The circuit is supplied at 110 V. What is the voltage across the 20 Ω resistor?
Answer: B. 60 V
The parallel group is (20 × 30) ÷ (20 + 30) = 12 Ω, so the total resistance is 10 + 12 = 22 Ω and the current is 110 ÷ 22 = 5 A. The voltage across the parallel group (and therefore across the 20 Ω resistor) is 5 × 12 = 60 V. Treating all three resistors as series elements (60 Ω, 1.83 A) gives 36.7 V, and 50 V is the drop across the 10 Ω resistor.
Question 2 · NEC Fundamentals, Branch Circuits, and Load Calculations
A 20 A, 120 V branch circuit supplies several 20 A general-purpose receptacles. What is the maximum rating of a single cord-and-plug-connected appliance that may be supplied by one of these receptacles?
Answer: A. 16 A
Table 210.21(B)(2) limits a cord-and-plug-connected load on a 20 A receptacle on a 20 A circuit to 16 A, which is 80% of the rating. The 10 A value is the 50% limit that applies to utilization equipment fastened in place under 210.23.
Question 3 · Overcurrentprotection
A 25 ft feeder tap is made from a feeder protected by a 300 A overcurrent device. The tap terminates in a single circuit breaker that limits the load to the tap ampacity, and the calculated load is 70 A. What is the minimum ampacity of the tap conductors?
Answer: D. 100 A
Section 240.21(B)(2) requires 25 ft tap conductors to have an ampacity of at least one-third of the feeder overcurrent device rating: 300 ÷ 3 = 100 A. That minimum exceeds the 70 A load, so 100 A governs. The 1/10 ratio (30 A) applies only to the 10 ft tap rule.
Question 4 · Wiring Methods and Materials
A pull box has an angle pull of 4 AWG and larger conductors. One 3-in conduit and two 2-in conduits enter the same wall, and the conductors turn toward an adjacent wall. What is the minimum distance from that wall to the opposite wall?
Answer: C. 22 in
Section 314.28(A)(2) requires 6 times the largest trade size plus the sum of the other raceways on the same wall: 6 × 3 + 2 + 2 = 22 in. Eighteen inches ignores the other raceways, 24 in uses the 8× straight-pull rule, and 42 in multiplies all trade sizes by 6.
Question 5 · Special Occupancies, Equipment, And
In a process area of a chemical plant, hydrogen gas can be present in ignitable concentrations during normal operation. How is this area classified?
Answer: A. Class I, Division 1, Group B
Flammable gas makes the area Class I, and an ignitable concentration under normal operating conditions makes it Division 1. Hydrogen is a Group B gas. Division 2 applies when the gas is present only under abnormal conditions, Group D covers gases such as gasoline vapor, propane, and natural gas, and Group A is acetylene.
Question 6 · Electrical Theory And Calculations
Resistors of 5 Ω, 10 Ω, and 15 Ω are connected in series across a 120 V source. How much power is dissipated in the 15 Ω resistor?
Answer: D. 240 W
Total resistance is 5 + 10 + 15 = 30 Ω, so the current is 120 ÷ 30 = 4 A, and the 15 Ω resistor dissipates 4² × 15 = 240 W. Using the full source voltage across the 15 Ω resistor gives 960 W, 480 W is the total circuit power, and 160 W is the power in the 10 Ω resistor.
Question 7 · Workingspaceaboutelectricalequipment
A 40 A branch circuit supplies two receptacle outlets. Which receptacle ratings does the NEC permit on this circuit?
Answer: C. 40 A or 50 A
Table 210.21(B)(3) permits receptacles rated 40 A or 50 A on a 40 A circuit supplying two or more receptacles. A 30 A receptacle is too small for the circuit rating, and the table does not limit the circuit to a single receptacle rating.
Question 8 · Overcurrentprotection
A circuit breaker carries a slash rating of 480Y/277 V. On which system may it be applied?
Answer: C. A 480Y/277 V solidly grounded wye system
Section 240.85 permits a slash-rated breaker only in a solidly grounded circuit where the nominal voltage of any conductor to ground does not exceed the lower value and the voltage between conductors does not exceed the higher value. On ungrounded, corner- grounded, or impedance-grounded 480 V systems, the voltage to ground can reach 480 V, exceeding the 277 V rating.
Question 9 · Wiring Methods and Materials
In an angle pull, two 3-in conduits on adjacent walls of a pull box contain the same 4/0 AWG conductors. What is the minimum distance between the raceway entries inside the box?
Answer: A. 18 in
Section 314.28(A)(2) requires raceway entries that enclose the same conductor to be at least 6 times the trade size of the larger raceway apart: 6 × 3 = 18 in. Twenty-four inches uses the 8× straight-pull multiplier. The other values do not follow from either rule.
Question 10 · Special Occupancies, Equipment, And
In a grain elevator, grain dust is in the air in ignitable quantities during normal operation. How is the area classified?
Answer: B. Class II, Division 1, Group G
Combustible dust makes the location Class II, and dust in ignitable quantities under normal operation makes it Division 1. Grain, flour, wood, and plastic dusts are Group G. Group F is carbonaceous dust such as coal, Group E is combustible metal dust, and Class III covers fibers and flyings.
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