Journeyman Electrician Practice Test 21

Question 1: Which of the following does NOT affect the resistance of an electrical conductor?

• The length of the conductor
• The color of the conductor
• The temperature of the conductor
• The cross-sectional area of the conductor

Question 2: The maximum load on a feeder or branch circuit must not exceed ........................ of normal rating of the feeder or branch circuit.

• 80 %
• 75 %
• 90 %
• 85 %

Question 3: No. 12 Type T or TW wire in conduit has an ampacity of 20; if you install it in a 50 ⁰ C ambient, what is its new ampacity?

• 15 amperes
• 20 amperes
• 11.6 amperes
• 14.6 amperes

Question 4: Two smaller wires need not have same cross sectional area to be connected in parallel to form a large wire.

• True
• False

Question 5: For equipment supplied by two ungrounded wires, ....................... switches may be used to disconnect the circuit.

• Single pole switches
• Double pole switches

Question 6: The voltage between conductors on  branch circuits supplying screw-shell lamp-holders, receptacles of dwelling units may not exceed............. volts, except for permanently connected appliances.

• 150
• 100
• 230
• 120

NEC Reference: NEC 210.6(A)

Question 7: The demand factor in calculating ampacity should never applied to branch circuits.

• True
• False

Question 8: The current in electrical circuit takes the least resistance path.

• True
• False

Question 9: An AC system of less than 50 Volts must be grounded which of the following conditions?

• If the supply transformer voltage exceeds 100 volts to ground.
• If the supply transformer is ungrounded
• if it is used as feeder conductor

NEC Reference: NEC 250.20(A)

Question 10: The total current flows through the 3-wire single phase electrical system is .................................

• the sum of the current flowing in two hot conductors
• the difference between the current flowing in two hot conductors

Question 11: When conductors are connected in parallel to increase ampacity, they must have the same .............

• Length only
• Length, size, type, and material
• Color and size
• Size and color only

NEC Reference: NEC 310.10(H)

Question 12: What is the minimum size conductor allowed to be run in parallel per NEC 310.10(H)(1)?

• No. 4 AWG
• No. 2 AWG
• 1/0 AWG
• No. 8 AWG

NEC Reference: NEC 310.10(H)(1)

Question 13: Why must conductor ampacity be derated when the ambient temperature is higher than the conductor rating?

• Because higher ambient means lower voltage
• To prevent the insulation from overheating and failing
• Because the NEC requires a safety factor only
• Higher ambient increases conductor resistance only

Question 14: In a dwelling unit, what is the maximum voltage between conductors allowed on a branch circuit that supplies screw-shell lampholders?

• 120 volts
• 150 volts
• 230 volts
• 300 volts

NEC Reference: NEC 210.6(A)

Question 15: Which of the following is NOT a standard ampere rating for fuses and circuit breakers listed in NEC 240.6(A)?

• 50 amperes
• 55 amperes
• 60 amperes
• 70 amperes

NEC Reference: NEC 240.6(A)

Question 16: What is the purpose of applying a demand factor to feeder and service conductor calculations?

• To increase the size of the service entrance
• To allow feeder conductors to be smaller than the total connected load
• To determine the number of branch circuits required
• To allow branch circuit conductors to be sized smaller

Question 17: An AC system of less than 50 volts must be grounded when the supply transformer primary voltage exceeds .............

• 50 volts to ground
• 150 volts to ground
• 120 volts to ground
• 240 volts to ground

NEC Reference: NEC 250.20(A)

Question 18: In a 3-wire single-phase system (120/240V), the neutral wire carries the current that is .............

• The sum of both hot conductor currents
• The difference between the two hot conductor currents
• Always zero regardless of load
• Equal to the largest hot conductor current

Question 19: How much free conductor must be left inside a junction box or outlet box for making connections?

• 3 inches
• 6 inches
• 8 inches
• 12 inches

NEC Reference: NEC 300.14

Question 20: Rigid Metal Conduit (RMC) is permitted to be used in which locations?

• Dry locations only
• All locations including hazardous and wet locations
• Wet locations only
• Exposed locations only

NEC Reference: NEC 344.10

Question 21: The size of the grounding electrode conductor (GEC) is determined by .............

• The voltage of the service
• The size of the service entrance conductors
• The number of circuits in the panel
• The length of the GEC run

NEC Reference: NEC 250.66

Question 22: If a single ground rod does not have a resistance to ground of 25 ohms or less, what must be done?

• Replace the ground rod with a water pipe electrode
• Install a second electrode at least 6 feet away
• Add more wire to the ground rod to increase contact
• No action needed — 25 ohms is just a recommendation

NEC Reference: NEC 250.56

Question 23: What is the maximum continuous load permitted on a 20-ampere branch circuit?

• 20 amperes
• 16 amperes
• 18 amperes
• 15 amperes

NEC Reference: NEC 210.20(A)

Question 24: Why is a double-pole (2-pole) switch required for equipment connected to two ungrounded (hot) conductors?

• Because single-pole switches are only for lighting
• To disconnect both hot conductors at the same time and fully de-energize the equipment
• Because 2-pole switches are cheaper
• Single-pole switches cannot handle 240V loads due to current limits

Question 25: What is the minimum depth of working clearance in front of a 120/240V panelboard where live parts are on one side and a grounded wall is on the other side?

• 2 feet
• 3 feet
• 4 feet
• 6 feet

NEC Reference: NEC 110.26(A)(1)

Question 26: What is the minimum headroom required in the working space in front of electrical equipment such as panelboards and motor control centers?

• 5 feet
• 6 feet
• 6.5 feet
• 8 feet

NEC Reference: NEC 110.26(E)(1)

Question 27: Kirchhoff's Voltage Law (KVL) states that the sum of all voltages around a closed loop is .............

• Equal to the supply voltage only
• Always zero
• Equal to the largest resistance
• Always positive

Question 28: Kirchhoff's Current Law (KCL) states that the sum of currents entering a junction is .............

• Always greater than currents leaving
• Equal to the sum of currents leaving that junction
• Always zero
• Equal to the supply current only

Question 29: What does the "H" in conductor insulation designation THHN stand for?

• Hollow core
• Heat resistant
• High voltage rated
• Hard outer jacket

Question 30: A wattmeter connected to an AC circuit with inductive loads will read .............

• Apparent power in volt-amperes
• True power in watts
• Reactive power in VAR
• Power factor in percentage