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JOURNEYMAN NEC 2020

NEC 2020 Journeyman Practice Test 10

Free Online Journeyman Electrician Practice Test — NEC 2020 Edition 10This free 30-question practice test covers grounding electrode system details, transformer installation and vault rules, motor control circuits and overload protection, and a mixed review of branch circuits, box fill, and GFCI/AFCI rules. All questions and explanations are based on the 2020 NEC.

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Frequently Asked Questions

Yes — completely free with no account required. All questions include detailed explanations and NEC references.

Most state Journeyman exams have 80–100 questions covering NEC code, wiring methods, branch circuits, motor controls, and load calculations.

Most states require a 70–75% passing score. This practice test uses the same 70% pass threshold so you know where you stand.

Questions are written to the 2020 NEC. Check your state licensing board to confirm which edition your state has adopted.

How to Use This Practice Test

This NEC 2020 Journeyman Practice Test 10 has 30 questions with detailed answers and NEC references. Take the full test, review every wrong answer, and look up the NEC article it references before moving on.

Tip: This is an open-book exam — tab your NEC index and Articles 210, 250, and 430 before you start.

Topics covered: Branch circuits, grounding, wiring methods, load calculations, and motors.
Passing score: 70–75% (most states). Aim for 80% on practice tests so the real exam feels easy.
Questions: 30 multiple-choice, one correct answer each

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45 min

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NEC 2020 Journeyman Practice Test 10 — Question List

Question 1: Per NEC 250.52(A)(1), a metal underground water pipe may be used as a grounding electrode only if it is in direct contact with the earth for at least:

5 feet
10 feet
20 feet
25 feet

NEC Reference: NEC 250.52(A)(1)

Question 2: Per NEC 250.53(D)(2), a metal underground water pipe electrode used as a grounding electrode must be:

Supplemented by an additional grounding electrode of another recognized type
The only electrode ever required, with no supplement needed
Prohibited entirely as a grounding electrode
Used only for lightning protection, never for the service ground

NEC Reference: NEC 250.53(D)(2)

Question 3: Per NEC 250.52(A)(2), the metal frame of a building or structure may qualify as a grounding electrode if:

At least one structural member is in contact with earth for 10 feet or more, or bonded to another recognized electrode
Any steel beam anywhere in the building automatically qualifies
Only above-grade steel members qualify
Metal building frames can never be used as electrodes

NEC Reference: NEC 250.52(A)(2)

Question 4: Per NEC 250.104(A)(1), metal water piping installed in or attached to a building must be bonded, with the bonding jumper sized according to which table?

Table 250.66
Table 250.122
Table 430.52
Table 310.15(B)(16)

NEC Reference: NEC 250.104(A)(1)

Question 5: A service has multiple disconnecting means in separate enclosures, as permitted by NEC 230.71. Per NEC 250.64(D)(1), how may the grounding electrode conductor connection be arranged?

A common GEC may be tapped, with individual tap conductors run to each disconnect
A completely separate grounding electrode system is required for each disconnect
No grounding electrode conductor is required if there is more than one disconnect
Only the largest disconnect enclosure needs a GEC connection

NEC Reference: NEC 250.64(D)(1)

Question 6: A water meter is installed in the interior metal water piping that is used as part of the grounding electrode system. Per NEC 250.68(B), what must be done to maintain grounding continuity?

Install a bonding jumper around the water meter
Remove the water meter permanently
Nothing — continuity is not a concern at a water meter
Replace all metal piping with plastic

NEC Reference: NEC 250.68(B)

Question 7: Per NEC 430.72(B), the maximum overcurrent protection permitted for motor control circuit conductors depends on:

The conductor size and whether it extends beyond the controller enclosure
The color of the conductor insulation only
The brand of the controller
Control circuit conductors never require overcurrent protection

NEC Reference: NEC 430.72(B)

Question 8: Per NEC 430.109(A)(1), the disconnecting means for a motor circuit must generally be which type of device?

A horsepower-rated motor-circuit switch or listed molded case circuit breaker/switch
Any ordinary residential light switch
A standard duplex receptacle
A twist-off wire nut

NEC Reference: NEC 430.109(A)(1)

Question 9: Per NEC 430.7(B) and Table 430.7(B), the "code letter" marked on a motor nameplate indicates:

Locked-rotor kVA per horsepower
The manufacturer's warranty period
The motor's operating voltage only
The wire color code for the motor leads

NEC Reference: NEC 430.7(B)

Question 10: Per NEC 430.22(B), branch-circuit conductors between the controller and a multispeed motor must be sized based on:

125% of the highest full-load current rating among the speeds
The average of all the speed current ratings
Only the lowest speed current rating
A fixed value regardless of nameplate current

NEC Reference: NEC 430.22(B)

Question 11: Per NEC 430.23(A), for a continuous-duty wound-rotor motor, the secondary conductors between the motor and its controller must have an ampacity of at least:

100% of the secondary full-load current
110% of the secondary full-load current
125% of the secondary full-load current
150% of the secondary full-load current

NEC Reference: NEC 430.23(A)

Question 12: Per NEC 430.36, where fuses are used to provide motor overload protection, how must they be arranged?

A fuse must be inserted in each ungrounded conductor
A single fuse on the neutral is sufficient
No fuses are permitted for overload protection
Only one fuse total is required regardless of phase count

NEC Reference: NEC 430.36

Question 13: Per NEC 430.37 and Table 430.37, a 3-phase, 3-wire motor circuit protected by separate overload relays generally requires how many overload units, one in each ungrounded conductor?

One
Two
Three
Four

NEC Reference: NEC 430.37

Question 14: A motor will not start with its branch-circuit short-circuit protective device set at the standard percentage from Table 430.52. Per the Exception to NEC 430.52(C)(1), what is generally permitted?

The device rating may be increased, up to specified maximum limits, to allow the motor to start
The motor circuit must be left completely unprotected
The motor must be replaced with a smaller unit
No increase is ever permitted under any condition

NEC Reference: NEC 430.52(C)(1)

Question 15: Per NEC 450.4, an autotransformer supplying a branch circuit must generally have a grounded conductor common to both the input and output circuits, primarily to prevent what hazard?

An overvoltage on the load side if the winding opens
Excess noise from the transformer core
Reduced efficiency only
Corrosion of the transformer case

NEC Reference: NEC 450.4(A)

Question 16: Per NEC Table 450.3(B), a transformer 600 volts or less, in an unsupervised location, protected only on the primary side, shall have its overcurrent device set at not more than _____ percent of the transformer's rated primary current (for a primary current of 9 amperes or more).

100 percent
125 percent
167 percent
250 percent

NEC Reference: NEC Table 450.3(B)

Question 17: Per NEC 450.41, a transformer vault must be located where it can be:

Ventilated to the outside air without flues or ducts, where practicable
Sealed completely with no ventilation of any kind
Located only below sea level
Located only in single-family dwellings

NEC Reference: NEC 450.41

Question 18: Per NEC 450.42, the walls, roof, and floor of a transformer vault must generally be constructed with a fire-resistance rating of at least how many hours, unless an automatic fire suppression system or other exception applies?

1 hour
2 hours
3 hours
6 hours

NEC Reference: NEC 450.42

Question 19: Per NEC 450.45, ventilation openings for a transformer vault must be located and sized to:

Dissipate the transformer heat and be located away from doors, windows, and combustibles
Be sealed shut to prevent any airflow
Face directly into an adjoining occupied office
Have no minimum size requirement whatsoever

NEC Reference: NEC 450.45

Question 20: A branch circuit supplies a continuous load of 24 amperes. Per NEC 210.19(A)(1), what is the minimum required conductor ampacity?

24 amperes
27 amperes
30 amperes
36 amperes

NEC Reference: NEC 210.19(A)(1)

Question 21: Per NEC 210.23(A)(2), a piece of cord-and-plug-connected utilization equipment on a 20 ampere branch circuit supplying multiple outlets must not exceed what rating?

12 amperes
16 amperes
20 amperes
24 amperes

NEC Reference: NEC 210.23(A)(2)

Question 22: A box contains one or more fixture studs or hickeys used to support a ceiling fixture. Per NEC 314.16(B)(3), how many box fill volume allowances are counted for these fittings, and based on what conductor size?

One allowance total, based on the largest conductor present
One allowance for every stud or hickey present
No allowance is ever required
Two allowances regardless of conductor size

NEC Reference: NEC 314.16(B)(3)

Question 23: Per NEC 590.6(A), 125-volt, 15-, 20-, and 30-ampere receptacle outlets that are not part of the permanent wiring, used to supply temporary power (such as on a construction site), must have what type of protection?

GFCI protection for personnel
AFCI protection only
No protection is required for temporary wiring
Only a warning label is required

NEC Reference: NEC 590.6(A)

Question 24: Per the Exception to NEC 210.12(A), a fire alarm system circuit installed using which wiring methods may be exempt from the AFCI protection requirement?

Rigid metal conduit, IMC, EMT, or steel-armored Type AC/MC cable
Type NM cable exclusively
Open knob-and-tube wiring
Uninsulated bare conductors

NEC Reference: NEC 210.12(A)

Question 25: Per NEC 352.10, rigid polyvinyl chloride (PVC) conduit is permitted for which of the following without additional corrosion protection?

Direct burial and wet or corrosive locations
Only dry indoor locations above 6 feet
Only Class I hazardous locations
It is never permitted underground

NEC Reference: NEC 352.10

Question 26: Per NEC 352.44, expansion fittings are required in a rigid PVC conduit run where the expected length change due to thermal expansion or contraction is:

1/8 inch or greater
1/4 inch or greater
1 inch or greater
6 inches or greater

NEC Reference: NEC 352.44

Question 27: Per NEC 430.52(A), the motor branch circuit must be protected against which two conditions by a device sized in accordance with Table 430.52?

Short-circuit and ground-fault conditions
Only voltage sags
Only harmonic distortion
Only lightning surges

NEC Reference: NEC 430.52(A)

Question 28: A single continuous-duty motor has a full-load current of 36 amperes as listed in the NEC motor full-load current tables. Per NEC 430.22(A), what is the minimum required branch-circuit conductor ampacity?

36 amperes
40 amperes
45 amperes
50 amperes

NEC Reference: NEC 430.22(A)

Question 29: What is the primary purpose of motor overload protection required under NEC Article 430, Part III, as distinguished from branch-circuit short-circuit protection under Part IV?

Protects against sustained excessive current from motor overloading, not instantaneous faults
Protects only against lightning strikes
Serves no functional safety purpose
Replaces the need for any branch-circuit protection

NEC Reference: NEC Article 430

Question 30: Per NEC Table 250.66, a service has 2/0 AWG copper ungrounded conductors. What is the minimum size copper grounding electrode conductor required (assuming the electrode is not a rod, pipe, plate, or ground ring)?

6 AWG copper
4 AWG copper
2 AWG copper
1/0 AWG copper

NEC Reference: NEC Table 250.66

Key NEC References for This Test

Article	What It Covers
Art. 100	Definitions — know: feeder, branch circuit, OCPD, dwelling unit
Art. 210	Branch Circuits — GFCI/AFCI locations, circuit ratings, outlet spacing (most tested)
Art. 220	Load Calculations — dwelling unit standard method
Art. 250	Grounding & Bonding — GEC sizing, electrode system, EGC
Art. 310	Conductors — ampacity (Table 310.12), insulation, derate rules
Art. 430	Motors — conductor 125% FLA, OCPD 250% FLA, overloads, disconnects

Study Tip: Tab Articles 210, 250, and 430 in your NEC before the exam. Know the Table 310.12 ampacity values for 14, 12, 10, 8, 6, and 4 AWG copper.

NEC 2020 Journeyman Practice Test 10

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NEC 2020 Journeyman Practice Test 10

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NEC 2020 Journeyman Practice Test 10 — Question List

Question 1: Per NEC 250.52(A)(1), a metal underground water pipe may be used as a grounding electrode only if it is in direct contact with the earth for at least:

Question 2: Per NEC 250.53(D)(2), a metal underground water pipe electrode used as a grounding electrode must be:

Question 3: Per NEC 250.52(A)(2), the metal frame of a building or structure may qualify as a grounding electrode if:

Question 4: Per NEC 250.104(A)(1), metal water piping installed in or attached to a building must be bonded, with the bonding jumper sized according to which table?

Question 5: A service has multiple disconnecting means in separate enclosures, as permitted by NEC 230.71. Per NEC 250.64(D)(1), how may the grounding electrode conductor connection be arranged?

Question 6: A water meter is installed in the interior metal water piping that is used as part of the grounding electrode system. Per NEC 250.68(B), what must be done to maintain grounding continuity?

Question 7: Per NEC 430.72(B), the maximum overcurrent protection permitted for motor control circuit conductors depends on:

Question 8: Per NEC 430.109(A)(1), the disconnecting means for a motor circuit must generally be which type of device?

Question 9: Per NEC 430.7(B) and Table 430.7(B), the "code letter" marked on a motor nameplate indicates:

Question 10: Per NEC 430.22(B), branch-circuit conductors between the controller and a multispeed motor must be sized based on:

Question 11: Per NEC 430.23(A), for a continuous-duty wound-rotor motor, the secondary conductors between the motor and its controller must have an ampacity of at least:

Question 12: Per NEC 430.36, where fuses are used to provide motor overload protection, how must they be arranged?

Question 13: Per NEC 430.37 and Table 430.37, a 3-phase, 3-wire motor circuit protected by separate overload relays generally requires how many overload units, one in each ungrounded conductor?

Question 14: A motor will not start with its branch-circuit short-circuit protective device set at the standard percentage from Table 430.52. Per the Exception to NEC 430.52(C)(1), what is generally permitted?

Question 15: Per NEC 450.4, an autotransformer supplying a branch circuit must generally have a grounded conductor common to both the input and output circuits, primarily to prevent what hazard?

Question 16: Per NEC Table 450.3(B), a transformer 600 volts or less, in an unsupervised location, protected only on the primary side, shall have its overcurrent device set at not more than _____ percent of the transformer's rated primary current (for a primary current of 9 amperes or more).

Question 17: Per NEC 450.41, a transformer vault must be located where it can be:

Question 18: Per NEC 450.42, the walls, roof, and floor of a transformer vault must generally be constructed with a fire-resistance rating of at least how many hours, unless an automatic fire suppression system or other exception applies?

Question 19: Per NEC 450.45, ventilation openings for a transformer vault must be located and sized to:

Question 20: A branch circuit supplies a continuous load of 24 amperes. Per NEC 210.19(A)(1), what is the minimum required conductor ampacity?

Question 21: Per NEC 210.23(A)(2), a piece of cord-and-plug-connected utilization equipment on a 20 ampere branch circuit supplying multiple outlets must not exceed what rating?

Question 22: A box contains one or more fixture studs or hickeys used to support a ceiling fixture. Per NEC 314.16(B)(3), how many box fill volume allowances are counted for these fittings, and based on what conductor size?

Question 23: Per NEC 590.6(A), 125-volt, 15-, 20-, and 30-ampere receptacle outlets that are not part of the permanent wiring, used to supply temporary power (such as on a construction site), must have what type of protection?

Question 24: Per the Exception to NEC 210.12(A), a fire alarm system circuit installed using which wiring methods may be exempt from the AFCI protection requirement?

Question 25: Per NEC 352.10, rigid polyvinyl chloride (PVC) conduit is permitted for which of the following without additional corrosion protection?

Question 26: Per NEC 352.44, expansion fittings are required in a rigid PVC conduit run where the expected length change due to thermal expansion or contraction is:

Question 27: Per NEC 430.52(A), the motor branch circuit must be protected against which two conditions by a device sized in accordance with Table 430.52?

Question 28: A single continuous-duty motor has a full-load current of 36 amperes as listed in the NEC motor full-load current tables. Per NEC 430.22(A), what is the minimum required branch-circuit conductor ampacity?

Question 29: What is the primary purpose of motor overload protection required under NEC Article 430, Part III, as distinguished from branch-circuit short-circuit protection under Part IV?

Question 30: Per NEC Table 250.66, a service has 2/0 AWG copper ungrounded conductors. What is the minimum size copper grounding electrode conductor required (assuming the electrode is not a rod, pipe, plate, or ground ring)?

Key NEC References for This Test

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