Journeyman Electrician Practice Test 26

Question 1: What is the largest trade size of flexible metal conduit (FMC) permitted?

• ½ in.
• 2 in.
• 4 in.
• 6 in.

NEC Reference: NEC 348.20(B)

Question 2: An impedance heating system for a pipeline is supplied through a transformer. What type of transformer is required?

• A shielded dual-winding transformer
• An autotransformer of any rating
• A buck-boost transformer
• Any transformer with a 30 V secondary

NEC Reference: NEC 427.26

Question 3: What minimum ampacity must the branch-circuit conductors have for a 5 hp, 230-volt, single-phase motor?

• 62.5 A
• 35 A
• 32.2 A
• 28 A

NEC Reference: NEC 430.22 and Table 430.248

Question 4: Which panelboard circuit directory entry does NOT comply with 408.4(A)?

• "Kitchen countertop receptacles, north wall"
• "Water heater"
• "Furnace and air handler"
• "Bob's room"

NEC Reference: NEC 408.4(A)

Question 5: A 120-volt, 30-ampere branch circuit supplies a cord-and-plug-connected room air conditioner and also other outlets. What is the maximum rating of the air conditioner?

• 15 A
• 20 A
• 24 A
• 30 A

NEC Reference: NEC 440.62(C)

Question 6: The supply voltage to a loaded induction motor drops. What happens to the slip?

• It increases
• It decreases
• It stays exactly the same
• It becomes zero

Question 7: A mobile home is supplied by a power-supply cord. How many conductors must the cord have?

• 2
• 3
• 4
• 5

NEC Reference: NEC 550.10(B) and (C)

Question 8: Which type of AC motor is the most widely used in industry?

• Synchronous motor with DC field
• Universal (series) motor
• Shaded-pole fan motor
• Squirrel-cage induction motor

Question 9: Six mobile home lots are supplied by one feeder. What demand factor applies under Table 550.31?

• 28%
• 29%
• 33%
• 35%

NEC Reference: NEC 550.31 and Table 550.31

Question 10: What is the operating (hot) resistance of a 100-watt, 120-volt lamp?

• 0.83 Ω
• 1.2 Ω
• 83 Ω
• 144 Ω

Question 11: What is the general minimum trade size of flexible metal conduit (FMC)?

• ½ in.
• 1 in.
• ¾ in.
• ⅜ in.

NEC Reference: NEC 348.20(A)

Question 12: What is the synchronous speed of a 4-pole induction motor operating on 60 Hz power?

• 3600 RPM
• 1800 RPM
• 900 RPM
• 1200 RPM

Question 13: Slip in an induction motor is the difference between .............

• The supply voltage and the back-EMF
• The synchronous speed and the actual rotor speed
• The starting torque and the running torque
• The input power and the output power

Question 14: Where must the service equipment for a mobile home be located?

• Anywhere within 100 ft of the lot
• Mounted on the mobile home itself
• At the park office building
• In sight, within 30 ft of the home

NEC Reference: NEC 550.32(A)

Question 15: Why may a "delta" (3-phase) breaker not be installed in a panelboard that has only two bus bars?

• It costs too much for most panels
• It needs a special tool to install it
• It is listed only for dwelling units
• 3-phase devices need three bus bars

NEC Reference: NEC 408.36(C)

Question 16: A load draws 12 kW of true power and 9 kVAR of reactive power. What is its apparent power?

• 3 kVA
• 15 kVA
• 21 kVA
• 108 kVA

Question 17: For a manufactured home installed in a mobile home park, the supply cord or feeder assembly connects from the park pedestal to .............

• The utility transformer
• The manufactured home distribution panel or cord inlet
• Any outdoor receptacle on the home
• The home's water heater disconnect

NEC Reference: NEC 550.10

Question 18: A 30-ampere, 120-volt branch circuit supplies only one cord-and-plug connected room air conditioner. What is the maximum current the air conditioner may draw?

• 30 amperes
• 15 amperes
• 24 amperes
• 20 amperes

NEC Reference: NEC 440.62(B)

Question 19: Why is a 3-phase induction motor considered "self-starting" while a single-phase induction motor is not?

• 3-phase motors have larger windings
• 3-phase supply creates a rotating magnetic field that provides starting torque automatically
• 3-phase motors run at higher speed
• Single-phase motors use more current

Question 20: When sizing motor branch circuit conductors and overcurrent protection, the full load current (FLC) used for calculations must come from .............

• The motor nameplate
• NEC Tables 430.247 through 430.250
• The motor manufacturer's specification sheet
• The calculated demand load

NEC Reference: NEC 430.6(A)(1)

Question 21: A 120/240-volt panelboard (150 V to ground) faces another panelboard with exposed live parts across the aisle (Condition 3). What is the minimum working space depth?

• 4 ft
• 3½ ft
• 3 ft
• 2 ft

NEC Reference: NEC 110.26(A)(1) and Table 110.26(A)(1)

Question 22: Fixed electric space-heating equipment is a continuous load. A 5,000 W, 240-volt baseboard heater is installed. What minimum ampacity must its branch-circuit conductors have?

• 20.8 A
• 24.0 A
• 26.0 A
• 31.3 A

NEC Reference: NEC 424.4(B)

Question 23: In an AC circuit supplying inductive loads (motors, transformers), the current waveform .............

• Leads the voltage
• Lags behind the voltage
• Is always in phase with the voltage
• Has a higher frequency than the voltage

Question 24: The service entrance cable or individual conductors at the service head (weatherhead) must be formed into a ............. to prevent water entry into the service.

• Straight splice covered with tape
• Drip loop to prevent water entry
• Tight upward bend
• Weatherproof junction box connection

NEC Reference: NEC 230.54(F)

Question 25: Service-entrance cable that is subject to physical damage must be protected by:

• RMC, IMC, EMT, Sch. 80 PVC or RTRC-XW
• Nothing, if it is over 6 ft above grade
• Schedule 40 PVC conduit only
• Two layers of tape wrapping

NEC Reference: NEC 230.50(A)

Question 26: Joule's Law states that the heat energy produced in a conductor is proportional to .............

• Current only (I)
• Current squared times resistance times time (I²Rt)
• Voltage squared (V²)
• Resistance only (R)

Question 27: Feeder conductors installed on marina docks must have ground-fault protection set at not more than:

• 30 mA
• 100 mA
• 300 mA
• 1,200 A

NEC Reference: NEC 555.35(A)(3)

Question 28: Under the 2023 NEC, what is the maximum phase-to-phase voltage of pier power distribution systems at a marina (where not serviced only by qualified personnel)?

• 120 V
• 250 V
• 480 V
• 1,000 V

NEC Reference: NEC 555.5

Question 29: Which fixed electric space-heating equipment requires a disconnecting means?

• Only 3-phase heating equipment
• Only heaters rated over 1,000 W
• All fixed space-heating equipment
• Only heaters rated over 240 V

NEC Reference: NEC 424.19

Question 30: To improve (raise) the power factor of a system with many inductive loads (motors), which of the following is connected to the system?

• Additional inductors (reactors)
• Capacitors connected in parallel with the load
• Resistors in series with the load
• A higher voltage transformer