IEC Independent Electrical Contractors Journeyman Electrician Exam — Questions and Answers

Question 1: Which type of fire extinguisher is appropriate for use on an energized electrical fire?

Class C (CO2, dry chemical, or halon) (Correct answer)
Class B (CO2 or dry chemical)
Class D (dry powder)
Class A (water-based)

Correct answer: Class C (CO2, dry chemical, or halon)

Class C extinguishers use non-conductive agents such as CO2, dry chemical, or halon, making them safe for use on energized electrical fires.

Question 2: A residential air conditioning unit draws 24 amperes at 240 volts and the electric heat load is 10 kW. Which load is omitted from the service calculation per NEC 220.60?

The air conditioning load is omitted
The heating load is omitted and AC used at 125%
The smaller of the two loads is omitted (Correct answer)
Both are included at 100%

Correct answer: The smaller of the two loads is omitted

NEC 220.60 permits omitting the smaller of the non-coincident heating or cooling loads since both are unlikely to operate simultaneously.

Question 3: In a dwelling, at least how many ampere branch circuit must be provided for bathroom receptacles?

20-ampere (Correct answer)
100-ampere
21-ampere
10-ampere

Correct answer: 20-ampere

Explanation: According to the National Electrical Code (NEC), a minimum of a 20-ampere branch circuit must be provided for bathroom receptacles in a dwelling. This circuit is dedicated to powering the outlets in the bathroom and is required to meet the electrical demands of modern bathroom appliances and devices.

Question 4: In a Class I, Division 2 location, which of the following is NOT required to be explosion-proof?

Switches and circuit breakers
Luminaires
Conduit seals
General-purpose motors that won't arc normally (Correct answer)

Correct answer: General-purpose motors that won't arc normally

In Division 2 locations, motors that are not normally arcing and are totally enclosed may be used without explosion-proof listing, unlike Division 1.

Question 5: When is it permitted to connect the neutral bar and ground bar together in a subpanel?

When the subpanel is fed by a 3-wire feeder
Never — neutral and ground must always be separate in subpanels (Correct answer)
When the feeder originates from a separately derived system
When the subpanel is located in the same building as the main panel

Correct answer: Never — neutral and ground must always be separate in subpanels

In a subpanel (remote distribution panel), the neutral and equipment grounding conductors must always be kept separate to prevent objectionable current on grounding paths.

Question 6: Per the NEC, what is the maximum number of overcurrent devices permitted in a lighting and appliance branch-circuit panelboard?

24
36
60
42 (Correct answer)

Correct answer: 42

NEC 408.36 limits lighting and appliance branch-circuit panelboards to a maximum of 42 overcurrent devices.

Question 7: What is plugging as a method of motor braking?

Reversing the phase sequence of the motor while it is running to create braking torque (Correct answer)
Applying DC to the stator after disconnecting AC power
Using a mechanical friction brake
Removing power and allowing the motor to coast to a stop

Correct answer: Reversing the phase sequence of the motor while it is running to create braking torque

Plugging reverses the phase sequence applied to the motor while it is still rotating, creating a reverse rotating field that produces braking torque.

Question 8: Which insulation type is listed for use in wet locations as well as dry locations, making it suitable for outdoor branch circuit wiring in conduit?

TW
THHN
THWN (Correct answer)
RHH

Correct answer: THWN

THWN (Thermoplastic, Heat- and Moisture-Resistant, Nylon-jacketed) insulation is listed for both wet and dry locations and is commonly used in outdoor conduit runs.

Question 9: What action is required when a splice is made in a branch circuit conductor inside a conduit?

The splice must be soldered before taping
The splice must be enclosed in an accessible junction box (Correct answer)
Splices are never permitted inside conduit
The splice must be taped with electrical tape only

Correct answer: The splice must be enclosed in an accessible junction box

NEC Section 300.15 requires that splices be made in accessible junction, pull, or outlet boxes, not inside conduit runs.

Question 10: When NM cable passes through a floor, what protection is required?

No protection is needed if the cable is secured
The cable must be placed inside PVC conduit for at least 12 inches above the floor
The cable must be protected by a minimum 6-inch guard from the floor and a bushing at the top (Correct answer)
The cable must be enclosed in rigid metal conduit for the entire floor thickness

Correct answer: The cable must be protected by a minimum 6-inch guard from the floor and a bushing at the top

NEC 334.15(C) requires NM cable passing through a floor to be enclosed in rigid metal conduit, IMC, Schedule 80 PVC, or equivalent protection for at least 6 inches above the floor, with a bushing at the top.

Question 11: For fixed electric space heating, NEC 220.51 requires that heating loads be calculated at what percentage of the total connected load?

125%
65%
100% (Correct answer)
80%

Correct answer: 100%

NEC 220.51 requires fixed electric space heating to be calculated at 100% of the total connected load with no demand factor reduction.

Question 12: The time constant (τ) of an RC series circuit determines:

The resonant frequency of the circuit
The maximum voltage across the resistor
The steady-state current
The rate at which the capacitor charges or discharges (Correct answer)

Correct answer: The rate at which the capacitor charges or discharges

τ = R × C; after one time constant the capacitor reaches about 63.2% of supply voltage.

Question 13: When connecting two single-phase transformers in parallel, which of the following is NOT a requirement for proper parallel operation?

Same impedance percentages
Identical kVA ratings (Correct answer)
Same voltage ratios (turns ratio)
Same polarity

Correct answer: Identical kVA ratings

Transformers operating in parallel do not need identical kVA ratings; they must have the same voltage ratios, polarity, and impedance percentages for proper load sharing.

Question 14: A 120-volt, 20-ampere branch circuit feeds a small office. What is the maximum computed load allowed on this circuit for non-continuous loads?

20 amperes (Correct answer)
16 amperes
12 amperes
24 amperes

Correct answer: 20 amperes

Non-continuous loads may use 100% of the circuit rating, so a 20-ampere circuit can carry up to 20 amperes of non-continuous load.

Question 15: Kirchhoff's Current Law (KCL) states that:

Voltage drops are additive in parallel circuits
The sum of voltages around any closed loop equals zero
The sum of currents entering a node equals the sum leaving it (Correct answer)
Current is proportional to resistance

Correct answer: The sum of currents entering a node equals the sum leaving it

KCL states that the algebraic sum of all currents at any node in a circuit equals zero (current in = current out).

Question 16: How many feet should an extension ladder extend above the top of a building to ensure proper safety and be securely anchored?

10 feet
3 feet (Correct answer)
6 feet
12 feet

Correct answer: 3 feet

Explanation: An extension ladder should extend 3 feet above the top of the building and be secured. This extension provides stability and ensures safe access to and from the roof or elevated area.

Question 17: A dwelling has 3,500 sq ft of living space. Using NEC 220.12, what is the general lighting load at 3 VA per sq ft?

8,000 VA
12,000 VA
7,000 VA
10,500 VA (Correct answer)

Correct answer: 10,500 VA

3,500 sq ft × 3 VA/sq ft = 10,500 VA for general lighting and receptacle loads.

Question 18: Which NEC table is used to determine the allowable ampacity of conductors in conduit based on temperature rating and insulation type?

Table 250.66
Table 310.16 (Correct answer)
Table 220.12
Table 430.52

Correct answer: Table 310.16

NEC Table 310.16 lists the allowable ampacities of insulated conductors rated up to 2000V in raceway, cable, or earth.

Question 19: What is the minimum burial depth for a ground ring used as a grounding electrode per NEC 250.52(A)(4)?

12 inches
24 inches (2.5 feet) (Correct answer)
18 inches
36 inches

Correct answer: 24 inches (2.5 feet)

NEC 250.52(A)(4) requires the ground ring to be buried at least 2.5 feet (30 inches) below the surface of the earth.

Question 20: For a grain storage elevator, the area within 3 feet of any opening in a belt or bucket elevator housing is classified as:

Class III, Division 1
Class II, Division 1 (Correct answer)
Unclassified
Class II, Division 2

Correct answer: Class II, Division 1

NEC 511.3 Table defines the area within 3 feet of openings in grain elevator housings as Class II, Division 1 due to constant grain dust presence.

Question 21: A variable frequency drive (VFD) controls motor speed primarily by varying the:

Number of motor poles
Supply frequency and voltage supplied to the motor (Correct answer)
Rotor resistance
Supply voltage only

Correct answer: Supply frequency and voltage supplied to the motor

VFDs control motor speed by simultaneously varying the output frequency and voltage (maintaining a constant V/Hz ratio) supplied to the motor.

Question 22: For a 240-volt, 2-wire branch circuit (no neutral), what conductors are present?

Two hot conductors and one grounding conductor (Correct answer)
One hot, one neutral, and one grounding conductor
One hot and one grounding conductor
Two hot conductors only, with no grounding required

Correct answer: Two hot conductors and one grounding conductor

A 240V 2-wire branch circuit has two ungrounded (hot) conductors and an equipment grounding conductor; no neutral is needed since neither leg is grounded.

Question 23: A conductor rated 90°C is terminated on a 75°C-rated device. Which temperature rating governs the conductor's usable ampacity at that termination?

75°C, since the termination limits the system (Correct answer)
60°C, always use the lowest standard rating
The average of 75°C and 90°C
90°C, since the conductor can handle it

Correct answer: 75°C, since the termination limits the system

Per NEC 110.14(C), ampacity must be limited to the lowest temperature rating of any connected component, so the 75°C termination governs.

Question 24: Per NEC 230.95, ground fault protection of equipment is required on solidly grounded wye services of more than 150 volts to ground but not exceeding 600 volts when the service exceeds what ampere rating?

800 amperes
600 amperes
1,000 amperes (Correct answer)
400 amperes

Correct answer: 1,000 amperes

NEC 230.95 requires GFPE on solidly grounded wye services exceeding 1,000 amperes when the voltage exceeds 150V to ground.

Question 25: What reading will the voltmeter display if its leads are connected to T3 and T4?

120 volts (Correct answer)
220 volts
110 volts
250 volts

Correct answer: 120 volts

Explanation: When the leads of the voltmeter are placed at T3 and T4, the meter will indicate 120 volts. This is because T3 and T4 represent the hot legs of a split-phase 240-volt system, and measuring between them gives the voltage across one phase, which is typically 120 volts in a residential electrical system.

Question 26: A 15-ampere branch circuit supplies both lighting outlets and receptacle outlets in a commercial office. What is the maximum rating of any single cord-and-plug-connected piece of equipment that is NOT fastened in place that can be used on this circuit?

10 amperes
7.5 amperes
12 amperes (Correct answer)
15 amperes

Correct answer: 12 amperes

According to NEC® 210.23(A)(1), on a 15- or 20-ampere branch circuit that supplies two or more outlets, the rating of any one cord-and-plug-connected utilization equipment not fastened in place shall not exceed 80% of the branch-circuit rating. For a 15-ampere circuit, this is 15A * 0.80 = 12A.

Question 27: Which three-phase transformer connection provides a neutral conductor on the secondary side?

Wye-Delta
Delta-Delta
Open Delta
Delta-Wye (Correct answer)

Correct answer: Delta-Wye

A Delta-Wye transformer provides a neutral from the center point of the wye-connected secondary windings.

Question 28: What is the primary advantage of a capacitor-start motor over a standard split-phase motor?

Lower noise operation
Higher starting torque due to greater phase displacement between windings (Correct answer)
Higher running efficiency
No need for a starting winding

Correct answer: Higher starting torque due to greater phase displacement between windings

The capacitor in the starting circuit creates nearly 90° phase displacement between the main and auxiliary winding currents, producing significantly higher starting torque.

Question 29: For a commercial kitchen with six pieces of equipment, NEC 220.56 states that the feeder or service calculated load shall not be less than the sum of the ________.

ratings of all equipment
largest equipment load plus 50% of the others
largest two kitchen equipment loads (Correct answer)
three smallest equipment loads

Correct answer: largest two kitchen equipment loads

NEC 220.56 contains a provision that, regardless of the demand factors applied from Table 220.56, the final calculated load for commercial kitchen equipment cannot be less than the sum of the largest two kitchen equipment loads. This ensures the service is adequately sized for a worst-case scenario where the two biggest pieces of equipment run simultaneously.

Question 30: How much is allowed for each branch circuit serving laundry receptacles when calculating residential service load?

3,000 volt-amperes
2,500 volt-amperes
1,500 volt-amperes (Correct answer)
2,000 volt-amperes

Correct answer: 1,500 volt-amperes

Explanation: When calculating residential service load, 1,500 volt-amperes are allowed for each branch circuit serving laundry receptacles. This allowance accounts for the typical load of laundry appliances such as washing machines and dryers, ensuring that the electrical system is adequately sized to handle the expected demand.

Question 31: When installing a panelboard in a residential garage, what NEC requirement applies?

It requires a dedicated circuit
It must be mounted at least 8 feet above the floor
It must be rated for outdoor use only
Working space clearances of 36 inches depth must be maintained (Correct answer)

Correct answer: Working space clearances of 36 inches depth must be maintained

NEC 110.26 requires a minimum of 36 inches of clear working space in front of electrical panels.

Question 32: What is the NEC-required minimum clearance from the top of a window opening for service-entrance conductors or overhead branch circuit spans?

10 feet (3.0 m)
3 feet (900 mm) (Correct answer)
4 feet (1.2 m)
No clearance required if conductors are insulated

Correct answer: 3 feet (900 mm)

NEC Section 230.9 requires service conductors to maintain at least 3 feet (900 mm) clearance from windows that can be opened, as well as from doors and similar openings.

Question 33: How many 15-ampere, 120-volt branch circuits are required per NEC for general lighting in a 2,400 sq ft dwelling unit using a 3 VA/sq ft load?

2 circuits
4 circuits
5 circuits
3 circuits (Correct answer)

Correct answer: 3 circuits

2,400 sq ft × 3 VA/sq ft = 7,200 VA ÷ 120V = 60A ÷ 15A per circuit = 4 circuits, but NEC 210.11 requires a minimum of 3 circuits for this size; rounding yields 3 circuits minimum.

Question 34: For a commercial occupancy, NEC 220.42 allows a demand factor of 50% on lighting loads exceeding how many volt-amperes?

3,000 VA
20,000 VA (Correct answer)
10,000 VA
50,000 VA

Correct answer: 20,000 VA

NEC Table 220.42 permits a 50% demand factor on the portion of the lighting load above 20,000 VA for certain commercial spaces.

Question 35: According to Faraday's Law, EMF is induced in a conductor when:

The magnetic flux through it changes (Correct answer)
It is placed in a static magnetic field
Current flows through it
It is heated

Correct answer: The magnetic flux through it changes

Faraday's Law states that induced EMF is proportional to the rate of change of magnetic flux through the conductor.

Question 36: Under what location classification would a luminaire installed under a covered breezeway need to be marked as suitable for?

A green location
A damp location (Correct answer)
A dry location
A wet location

Correct answer: A damp location

Explanation: A luminaire installed under a covered breezeway would need to be marked as suitable for a ""damp"" location. Even though it's covered, it can still be exposed to moisture from humidity or occasional splashing, so the fixture needs to be designed to withstand these conditions safely.

Question 37: A service disconnect rated 200A feeds a panel. Per NEC 230.90, the service overcurrent device must be rated at or below:

150A
175A
200A (Correct answer)
250A

Correct answer: 200A

NEC 230.90 requires the service overcurrent device to be rated not more than the ampacity of the service conductors, which here supports 200A.

Question 38: In a Class II hazardous location, the primary hazard is from:

Flammable gases and vapors
Explosive atmospheres from fibers
Combustible dust (Correct answer)
Flammable liquids

Correct answer: Combustible dust

Class II hazardous locations are defined by the presence of combustible dust that can ignite and create an explosive atmosphere.

Question 39: According to NEC 450.41, transformer vault walls, roofs, and floors must have a minimum fire resistance rating of how many hours?

1 hour
2 hours
3 hours (Correct answer)
4 hours

Correct answer: 3 hours

NEC 450.41 requires transformer vault construction to have a minimum 3-hour fire resistance rating to contain fire and protect the surrounding structure.

Question 40: In a Class I, Division 1 hazardous location, which wiring method is acceptable?

Type NM cable
Rigid metal conduit (RMC) (Correct answer)
Open wiring on insulators
Type AC cable

Correct answer: Rigid metal conduit (RMC)

Rigid metal conduit is approved for Class I, Division 1 locations because it provides the required explosion-proof enclosure integrity.

Question 41: When calculating the demand load for a residential range rated at 12 kW, what demand factor does NEC Table 220.55 apply for a single range?

70%
8 kW (Column C value) (Correct answer)
100%
80%

Correct answer: 8 kW (Column C value)

NEC Table 220.55, Column C assigns 8 kW demand for a single household cooking appliance rated 12 kW or less.

Question 42: What minimum ampacity service is required for a one-family dwelling under NEC 230.79(C)?

150 amperes
200 amperes
100 amperes (Correct answer)
60 amperes

Correct answer: 100 amperes

NEC 230.79(C) requires a minimum 100-ampere, 3-wire service for one-family dwellings.

Question 43: Which NEC article governs the installation of services, including service-entrance conductors?

Article 200
Article 310
Article 250
Article 230 (Correct answer)

Correct answer: Article 230

NEC Article 230 covers services, including service conductors, service equipment, and clearances.

Question 44: A new electrical installation has just been completed. According to NEC 110.7, the completed wiring installation must be free from short circuits, ground faults, or any connection to ground that is not...

approved by the property owner.
documented in the as-built drawings.
inspected by the general contractor.
required or permitted by the Code. (Correct answer)

Correct answer: required or permitted by the Code.

NEC 110.7 states that completed wiring installations shall be free from short circuits, ground faults, or any connections to ground other than as required or permitted elsewhere in the Code. This is a fundamental safety requirement for all electrical systems.

Question 45: What gauge is the smallest copper conductor permitted for branch circuits under NEC Article 210?

8 AWG
10 AWG
12 AWG
14 AWG (Correct answer)

Correct answer: 14 AWG

NEC Section 210.19 permits 14 AWG copper as the minimum conductor size for branch circuits, which corresponds to a 15-ampere rating.

Question 46: What does NEC 110.26(A)(1) Condition 3 combined with voltage over 600V (medium voltage) require for working space depth in installations over 600 volts?

Only qualified persons exempt from depth requirements at medium voltage
Depth increases significantly—NEC 110.34 governs with depths starting at 5 feet (Correct answer)
Medium voltage equipment is exempt from working space requirements if in a vault
The same 4-foot depth as for 0-600 volt installations

Correct answer: Depth increases significantly—NEC 110.34 governs with depths starting at 5 feet

For equipment over 600 volts, NEC 110.34 governs working space with greater depths (starting at 5 feet) to account for increased arc flash hazards.

Question 47: What is the primary purpose of tap connections on a transformer's primary winding?

To adjust the voltage ratio for variations in supply voltage (Correct answer)
To increase the transformer's kVA capacity
To provide multiple secondary voltage levels
To connect multiple transformers in parallel

Correct answer: To adjust the voltage ratio for variations in supply voltage

Primary taps allow the turns ratio to be adjusted in small increments (typically 2.5% or 5%) to compensate for supply voltage that is higher or lower than the transformer's nominal rating.

Question 48: When aluminum conductors are used for branch circuits, which minimum size is permitted for 15-ampere circuits under NEC Article 310?

12 AWG aluminum (Correct answer)
8 AWG aluminum
10 AWG aluminum
14 AWG aluminum

Correct answer: 12 AWG aluminum

NEC Table 310.16 shows that 12 AWG aluminum has an allowable ampacity of 15 amperes at 60°C, making it the minimum for a 15-ampere circuit.

Question 49: When conductors of different circuits are installed in the same raceway, which NEC adjustment factor must be applied?

Demand factor
Temperature correction factor
Voltage drop correction
Bundling or fill derating factor (Correct answer)

Correct answer: Bundling or fill derating factor

When more than three current-carrying conductors are in a raceway, NEC Table 310.15(C)(1) bundling derating factors must be applied to reduce allowable ampacity.

Question 50: What is the purpose of the 'interrupting rating' requirement found in NEC 110.9?

To specify the voltage rating of circuit breakers
To limit the maximum ampere rating of overcurrent devices
To ensure equipment can handle continuous load currents
To ensure protective devices can safely interrupt the maximum available fault current (Correct answer)

Correct answer: To ensure protective devices can safely interrupt the maximum available fault current

NEC 110.9 requires that overcurrent protective devices have an interrupting rating sufficient for the nominal circuit voltage and current that is available at the line terminals.

Question 51: A branch circuit runs 150 feet from the panelboard to a 120V, 10-ampere load. Which NEC guideline addresses keeping voltage drop within acceptable limits?

NEC 220.12 sets a hard 2% limit for branch circuits
Voltage drop is not addressed anywhere in the NEC
NEC 310.15 mandates a maximum 5% voltage drop for all circuits
NEC 210.19(A) Informational Note recommends voltage drop not exceed 3% on branch circuits (Correct answer)

Correct answer: NEC 210.19(A) Informational Note recommends voltage drop not exceed 3% on branch circuits

NEC Section 210.19(A) contains an Informational Note recommending that voltage drop on branch circuits not exceed 3% to maintain efficiency and equipment performance.

Question 52: What is the maximum voltage permitted for underwater pool lighting in a wet-niche fixture?

120 volts
15 volts
12 volts
30 volts (Correct answer)

Correct answer: 30 volts

NEC 680.23(A)(4) permits wet-niche luminaires to operate at no more than 150 volts between conductors, but the practical limit for underwater fixtures is 30 volts.

Question 53: What is the purpose of a motor's 'reduced voltage solid-state starter' (soft starter)?

To convert three-phase power to single-phase for the motor
To provide power factor correction during running
To gradually ramp up the voltage to the motor during starting to reduce inrush current and mechanical stress (Correct answer)
To vary the motor speed continuously during operation

Correct answer: To gradually ramp up the voltage to the motor during starting to reduce inrush current and mechanical stress

Soft starters use SCRs to gradually increase the voltage applied to the motor, reducing starting current and mechanical shock to the driven equipment.

Question 54: When calculating the service load for four household clothes dryers in an apartment building, what demand factor does NEC Table 220.54 apply?

70%
80% (Correct answer)
85%
100%

Correct answer: 80%

NEC Table 220.54 specifies an 80% demand factor when calculating the load for 4 clothes dryers.

Question 55: What is the minimum headroom required above the working space for electrical panelboards supplying branch circuits in commercial occupancies?

6.0 feet (1.8 m) or the height of the equipment, whichever is greater (Correct answer)
7.0 feet (2.1 m)
8.0 feet (2.4 m)
5.5 feet (1.7 m)

Correct answer: 6.0 feet (1.8 m) or the height of the equipment, whichever is greater

NEC Section 110.26(A)(3) requires a minimum headroom of 6.0 feet or the height of the equipment, whichever is greater, in front of electrical equipment.

Question 56: How much current is flowing in the neutral conductor if circuits 7 and 9, sharing a neutral in a multi-wire branch circuit, draw 13 amps and 16 amps, respectively?

3 amps (Correct answer)
2 amps
50 amps
20 amps

Correct answer: 3 amps

Explanation: In a multi-wire branch circuit, the neutral current is calculated by summing the unbalanced currents of the circuits sharing the neutral. In this case, circuit 7 is drawing 13 amps, and circuit 9 will draw 16 amps. Therefore, the unbalanced current is 3 amps (16 amps - 13 amps). So, 3 amps is flowing in the neutral.

Question 57: What factor primarily determines the voltage drop on a branch circuit conductor run?

Conductor length and load current (Correct answer)
Number of splices in the run
Type of conduit used
Insulation color

Correct answer: Conductor length and load current

Voltage drop is primarily a function of conductor resistance (related to length and wire gauge) multiplied by the load current.

Question 58: When is it permissible to use 10 AWG copper on a 30-ampere branch circuit per NEC Article 210?

When the 10 AWG conductor has a 90°C insulation rating
Never; 10 AWG copper is only rated 30A on a feeder
When the run is less than 50 feet to limit voltage drop
When the circuit supplies a single receptacle rated 30 amperes (Correct answer)

Correct answer: When the circuit supplies a single receptacle rated 30 amperes

NEC Section 210.21(B) permits a single 30-ampere receptacle outlet to be supplied by 10 AWG copper (30A at 75°C) on a 30-ampere branch circuit.

Question 59: In a dwelling unit, how many small-appliance branch circuits are required by NEC 210.11(C)(1) for kitchen, pantry, breakfast room, and dining room receptacles?

One 15-ampere circuit
Three 20-ampere circuits
At least two 20-ampere small-appliance branch circuits (Correct answer)
One 20-ampere circuit per countertop space

Correct answer: At least two 20-ampere small-appliance branch circuits

NEC Section 210.11(C)(1) mandates a minimum of two 20-ampere small-appliance branch circuits for receptacles in the kitchen, pantry, breakfast room, and dining room.

Question 60: A motor's locked rotor current (LRC) is typically how many times its full-load current (FLC)?

2 to 3 times FLC
6 to 10 times FLC (Correct answer)
1 to 2 times FLC
15 to 20 times FLC

Correct answer: 6 to 10 times FLC

Typical induction motors draw 6 to 10 times their full-load current during starting (locked rotor condition).

Question 61: In a motor branch circuit, the short-circuit and ground-fault protective device is sized larger than the conductor's ampacity. What is the primary reason for this allowance?

To provide overload protection for the motor.
To account for voltage drop over the length of the circuit.
To simplify the selection of overcurrent devices.
To allow for the high inrush current when the motor starts. (Correct answer)

Correct answer: To allow for the high inrush current when the motor starts.

NEC® Article 430 allows the branch-circuit short-circuit and ground-fault protective device to be sized higher than the conductor's ampacity to prevent tripping during the motor's starting period, which involves a high inrush current. Overload protection is a separate device.

Question 62: What is the minimum burial depth for rigid metal conduit (RMC) under a parking lot?

18 inches
12 inches (Correct answer)
6 inches
24 inches

Correct answer: 12 inches

NEC Table 300.5 requires RMC to be buried at least 6 inches under a parking lot when not subject to vehicular traffic, but 24 inches in other cases—however under parking lots with vehicle traffic the minimum is 24 inches.

Question 63: What is the unit of magnetic flux?

Gauss
Henry
Weber (Correct answer)
Tesla

Correct answer: Weber

The Weber (Wb) is the SI unit of magnetic flux, where 1 Wb = 1 V·s.

Question 64: Under NEC 110.26(E), where electrical equipment that could require examination, adjustment, or maintenance is installed above a suspended ceiling, what is required?

Access panels shall be provided and the working space requirements of 110.26(A) still apply above the ceiling (Correct answer)
A permanent ladder must be installed for access
The equipment is exempt from working clearance requirements if behind an access panel
Only equipment rated under 150 volts may be installed above suspended ceilings

Correct answer: Access panels shall be provided and the working space requirements of 110.26(A) still apply above the ceiling

NEC 110.26(E) requires that electrical equipment above suspended ceilings still meet working space requirements and have access panels provided.

Question 65: A 400-ampere service has a calculated load of 320 amperes. The neutral calculated load is 210 amperes. What is the neutral ampacity after applying the NEC 220.61 reduction?

168 amperes
147 amperes
200 amperes + 7 amperes = 207 amperes (Correct answer)
210 amperes

Correct answer: 200 amperes + 7 amperes = 207 amperes

200 A at 100% = 200 A; (210 A − 200 A) × 70% = 7 A; total neutral = 207 amperes per NEC 220.61.

Question 66: A 120/240V, single-phase, 3-wire service has a 20A load on phase A and a 15A load on phase B. What is the neutral current?

17.5A
35A
5A (Correct answer)
20A

Correct answer: 5A

In a single-phase 3-wire system, neutral current equals the difference between the two hot-leg currents: 20 − 15 = 5A.

Question 67: An electrician is installing Electrical Nonmetallic Tubing (ENT) in the walls of a new wood-frame residential construction. What is the maximum spacing interval required for securing and supporting the ENT?

4.5 feet
5 feet
6 feet
3 feet (Correct answer)

Correct answer: 3 feet

Per NEC Article 362.30(A), Electrical Nonmetallic Tubing (ENT) must be securely fastened at intervals not exceeding 3 feet (900 mm). Additionally, it must be secured within 3 feet of every outlet box, junction box, cabinet, or fitting. [10, 22, 23]

Question 68: When a motor is rewound with a higher number of turns per coil using thinner wire, the motor will have:

Same voltage but higher starting torque
Lower voltage rating and higher current draw
Same electrical characteristics with higher efficiency
Higher voltage rating and lower current draw (Correct answer)

Correct answer: Higher voltage rating and lower current draw

More turns increase the winding impedance, raising the voltage required and reducing the current drawn for equivalent power output.

Question 69: When must tap conductors be protected by an overcurrent device at the point where they receive their supply?

Exceptions in NEC 240.21 allow unprotected taps under specific length and ampacity conditions (Correct answer)
Only when the tap exceeds 10 feet
Only when the tap feeds a motor
Always, with no exceptions

Correct answer: Exceptions in NEC 240.21 allow unprotected taps under specific length and ampacity conditions

NEC Section 240.21 provides tap conductor exceptions that allow conductors to be run without overcurrent protection at the source under defined length and ampacity rules.

Question 70: In a motor control ladder diagram, the symbol for a normally open (NO) contact that is controlled by a pushbutton is:

Two parallel vertical lines
Two vertical lines with a diagonal line between them representing the actuator (Correct answer)
A circle with a line through it
A horizontal line with a diagonal arrow through it

Correct answer: Two vertical lines with a diagonal line between them representing the actuator

In ladder diagrams, a normally open pushbutton contact is represented by two vertical lines (the contact symbol) with a slanted line representing the actuator arm.

Question 71: Ground-fault protection of equipment (GFPE) per NEC 230.95 is required on solidly grounded wye services of more than 150V to ground but not exceeding 600V phase-to-phase when the service rating is at least:

800A (Correct answer)
600A
400A
1000A

Correct answer: 800A

NEC 230.95 requires GFPE on services rated 800A or more on solidly grounded wye systems meeting the voltage criteria.

Question 72: Unless specifically identified for a different temperature, conductors connected to terminals of equipment rated 100 amperes or less shall be sized based on what temperature rating from NEC Table 310.15(B)(16)?

75°C
60°C (Correct answer)
The temperature rating of the conductor insulation.
90°C

Correct answer: 60°C

NEC 110.14(C)(1)(a) requires that for equipment rated 100 amperes or less, the ampacity of the connected conductors must be based on the 60°C column of Table 310.15(B)(16), unless the equipment terminals are listed and marked for a higher temperature rating.

Question 73: A 240-volt, 30-ampere clothes dryer circuit is installed in a dwelling. What minimum load must be used for service calculation per NEC 220.54?

7,200 VA
3,000 VA
4,500 VA
5,000 VA (Correct answer)

Correct answer: 5,000 VA

NEC 220.54 requires each dryer to be calculated at 5,000 watts or the nameplate rating, whichever is larger.

Question 74: What is the minimum wire size needed to limit the voltage drop to 5% when running a 300 ft length of type NM-B cable to supply power to a 120 volt, 1/2 HP 8-amp load?

20 AWG
12 AWG
10 AWG (Correct answer)
100 AWG

Correct answer: 10 AWG

Explanation: To limit the voltage drop to 5% for a 300 ft run of NM-B cable to a 120-volt, 1/2 HP 8-amp load, a minimum wire size of 10 AWG is needed. This gauge ensures that the voltage drop over the distance of the cable remains within acceptable limits, maintaining proper voltage supply to the load.

Question 75: Which motor protection device opens the circuit when the motor windings reach an excessive temperature?

Voltage relay
Ground fault relay
Thermal protector (thermistor or thermostat embedded in windings) (Correct answer)
Current relay

Correct answer: Thermal protector (thermistor or thermostat embedded in windings)

Thermal protectors or PTC thermistors embedded in motor windings directly sense winding temperature and open the circuit when unsafe temperatures are reached.

Question 76: A capacitor in an AC circuit causes current to:

Lag voltage by 45°
Lead voltage by 90° (Correct answer)
Lag voltage by 90°
Be in phase with voltage

Correct answer: Lead voltage by 90°

In a purely capacitive circuit, current leads voltage by 90° (mnemonic: ICE — current leads in capacitors).

Question 77: What is the minimum branch circuit rating permitted for a single outlet on a household appliance circuit where the appliance nameplate rating is 12 amperes?

30 amperes
15 amperes (Correct answer)
25 amperes
20 amperes

Correct answer: 15 amperes

A 15-ampere branch circuit is sufficient when the single outlet serves an appliance rated at 12 amperes, since 12A does not exceed 80% of 15A for continuous loads.

Question 78: In a habitable room of a dwelling, what is the maximum distance a receptacle can be from any point measured horizontally along the floor line of an unbroken wall space?

6 feet (Correct answer)
8 feet
10 feet
12 feet

Correct answer: 6 feet

NEC® 210.52(A)(1) states that receptacles in habitable rooms of a dwelling must be installed so that no point measured horizontally along the floor line in any wall space is more than 6 feet from a receptacle outlet. This effectively means receptacles can be spaced a maximum of 12 feet apart.

Question 79: What is the NEC-required number of minimum small appliance branch circuits for a dwelling unit kitchen?

Three 20-ampere circuits
One 15-ampere circuit
Two 20-ampere circuits (Correct answer)
One 20-ampere circuit

Correct answer: Two 20-ampere circuits

NEC 210.11(C)(1) requires at least two 20-ampere small appliance branch circuits for the kitchen, dining, and pantry areas.

Question 80: NEC 110.22 requires that each disconnecting means be legibly marked. Which of the following is NOT required by this section?

Clear identification on circuit directory for panelboards
The purpose of the disconnecting means
Warning labels on series-rated equipment
The manufacturer's name on the disconnect (Correct answer)

Correct answer: The manufacturer's name on the disconnect

NEC 110.22 requires identification of purpose but does not require the manufacturer's name to be marked on the disconnecting means.

IEC Independent Electrical Contractors Journeyman Electrician Exam

The IEC (Independent Electrical Contractors) journeyman electrician exam tests knowledge of the National Electrical Code (NEC), electrical theory, wiring methods, conductors, branch circuits, motor controls, and electrical calculations required for journeyman electrician licensure.

Questions

240 min

Time Limit

70%

To Pass

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