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JOURNEYMAN NEC 2020

NEC 2020 Journeyman Practice Test 6

Free Online Journeyman Electrician Practice Test — NEC 2020 Edition 6This free 30-question practice test covers grounding electrodes and the grounding electrode system, bonding jumpers, overcurrent protection rules, and conductor ampacity under Table 310.15(B)(16). All questions and explanations are based on the 2020 NEC.

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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 6 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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NEC 2020 Journeyman Practice Test 6 — Question List

Question 1: At service equipment, the main bonding jumper connects the grounded (neutral) conductor to which of the following?

A driven ground rod only
The service equipment enclosure
The utility transformer neutral only
Nothing — the neutral must stay isolated at the service

NEC Reference: NEC 250.28

Question 2: Which of the following is specifically prohibited from being used as a grounding electrode?

Metal underground gas piping system
Metal frame of the building
Concrete-encased electrode (Ufer ground)
Ground ring

NEC Reference: NEC 250.52(B)(1)

Question 3: Per NEC Table 250.66, for a service with copper ungrounded conductors of 2 AWG or smaller, what is the minimum size copper grounding electrode conductor (GEC)?

6 AWG copper
8 AWG copper
4 AWG copper
10 AWG copper

NEC Reference: NEC Table 250.66

Question 4: Per NEC 250.53(A)(2), a single rod, pipe, or plate electrode with a resistance to earth greater than _____ ohms must be supplemented with an additional electrode.

10 ohms
25 ohms
15 ohms
50 ohms

NEC Reference: NEC 250.53(A)(2)

Question 5: A concrete-encased electrode (Ufer ground) using bare copper conductor must be at least how long to qualify as a grounding electrode?

10 feet
20 feet
6 feet
8 feet

NEC Reference: NEC 250.52(A)(3)

Question 6: A ground ring grounding electrode must consist of at least 20 feet of bare copper conductor not smaller than _____ encircling the building.

2 AWG
4 AWG
6 AWG
8 AWG

NEC Reference: NEC 250.52(A)(4)

Question 7: A driven ground rod electrode must have a minimum length of at least how many feet in contact with the soil?

5 feet
8 feet
10 feet
6 feet

NEC Reference: NEC 250.52(A)(5)

Question 8: Per NEC 250.53(A)(3), when two rod electrodes are used, they must be spaced not less than _____ apart to be effective.

3 feet
6 feet
10 feet
12 feet

NEC Reference: NEC 250.53(A)(3)

Question 9: Per NEC Table 250.122, what is the minimum size copper equipment grounding conductor (EGC) required for a circuit protected by a 20 ampere overcurrent device?

14 AWG
12 AWG
10 AWG
8 AWG

NEC Reference: NEC Table 250.122

Question 10: A feeder is protected by a 100 ampere circuit breaker. Per NEC Table 250.122, what is the minimum size copper equipment grounding conductor required?

10 AWG
8 AWG
6 AWG
4 AWG

NEC Reference: NEC Table 250.122

Question 11: Downstream of the service disconnecting means, which of the following is generally NOT a recognized equipment grounding conductor?

Rigid metal conduit
Electrical metallic tubing
The grounded (neutral) conductor
A bare copper conductor

NEC Reference: NEC 250.118

Question 12: Per NEC 250.104(B), metal piping systems (such as gas piping) that may become energized must be bonded to which of the following?

The service equipment enclosure, grounded conductor, GEC, or a grounding electrode
Nothing — bonding of gas piping is prohibited
Only a dedicated ground rod driven at the meter
Only the nearest metal water pipe

NEC Reference: NEC 250.104(B)

Question 13: For a separately derived system, such as a dry-type transformer secondary, where may the required system bonding jumper be installed per NEC 250.30(A)(1)?

At every panelboard fed from the transformer
At a single point — the source or the first disconnecting means, not both
At the nearest metal water pipe only
At any convenient junction box downstream

NEC Reference: NEC 250.30(A)(1)

Question 14: A feeder supplies a disconnecting means at a separate structure on the same property. Per NEC 250.32(B)(1), what is required at the structure regarding grounding?

An EGC must be run with the feeder; the neutral must stay isolated from the EGC and enclosure
The neutral must be bonded to the enclosure the same as at the service
No EGC is needed if a ground rod is driven at the structure
The neutral may be reduced to half the size of the ungrounded conductors

NEC Reference: NEC 250.32(B)(1)

Question 15: Grounding and bonding connections must be made in a way that does NOT create what condition, per NEC 250.6(A)?

Objectionable current over grounding conductors or paths
Excess voltage drop on branch circuits
Overloaded neutral conductors only
Corrosion of buried conduit

NEC Reference: NEC 250.6(A)

Question 16: Unless a specific exception applies, what is the maximum standard overcurrent protection permitted for a 12 AWG copper conductor?

15 amperes
20 amperes
25 amperes
30 amperes

NEC Reference: NEC 240.4(D)(5)

Question 17: Unless a specific exception applies, what is the maximum standard overcurrent protection permitted for a 10 AWG copper conductor?

20 amperes
25 amperes
30 amperes
40 amperes

NEC Reference: NEC 240.4(D)(7)

Question 18: A continuous load calculation results in a required conductor ampacity of 34 amperes, which is not a standard overcurrent device size. Per NEC 240.4(B) and 240.6(A), what should be done?

Round down to 30 amperes
Round up to the next standard size, 35 amperes
Use a non-standard 34 ampere breaker
The circuit cannot be installed

NEC Reference: NEC 240.4(B)

Question 19: Under the 10-foot tap rule of NEC 240.21(B)(1), which of the following is a required condition?

Tap conductors up to 10 feet long, sized to the load and terminating device, enclosed in raceway if leaving the enclosure
Tap conductors up to 50 feet long with no ampacity requirement
Tap conductors may be any length if run overhead
Tap conductors need no overcurrent protection at all

NEC Reference: NEC 240.21(B)(1)

Question 20: Under the 25-foot tap rule of NEC 240.21(B)(2), the tap conductors must have an ampacity of at least what fraction of the rating of the overcurrent device from which they are tapped?

One-half
One-third
One-fourth
Two-thirds

NEC Reference: NEC 240.21(B)(2)

Question 21: True or false: NEC 240.24(E) prohibits installing overcurrent devices, such as panelboards, in the bathrooms of dwelling units.

True
False
Only in commercial bathrooms
Only for fuses, not breakers

NEC Reference: NEC 240.24(E)

Question 22: Per the 2020 NEC Table 310.15(B)(16), what is the allowable ampacity of an 8 AWG copper conductor with 90°C insulation (such as THHN), in a raceway with no more than 3 current-carrying conductors at 30°C ambient?

50 amperes
55 amperes
60 amperes
65 amperes

NEC Reference: NEC Table 310.15(B)(16)

Question 23: Per the 2020 NEC Table 310.15(B)(16), what is the allowable ampacity of a 6 AWG copper conductor with 90°C insulation, in a raceway with no more than 3 current-carrying conductors at 30°C ambient?

65 amperes
70 amperes
75 amperes
80 amperes

NEC Reference: NEC Table 310.15(B)(16)

Question 24: A branch circuit uses 10 AWG copper THHN conductors. Table 310.15(B)(16) lists a 90°C ampacity of 40 amperes for this conductor, but what is the maximum standard breaker size actually permitted to protect it?

40 amperes
35 amperes
30 amperes
45 amperes

NEC Reference: NEC 240.4(D)(7)

Question 25: Per NEC 310.15(B)(3)(a), when a raceway or cable contains 4 through 6 current-carrying conductors, the table ampacity of each conductor must be adjusted to what percentage?

90 percent
80 percent
70 percent
50 percent

NEC Reference: NEC 310.15(B)(3)(a)

Question 26: Per NEC 250.24(A)(5), on the load side of the service disconnecting means, the grounded (neutral) conductor must:

Remain isolated from equipment grounding conductors and the enclosure
Be bonded again at every panel for extra safety
Be removed entirely
Be connected to the ground bar only in metal buildings

NEC Reference: NEC 250.24(A)(5)

Question 27: Per NEC 250.50, if a metal underground water pipe, a concrete-encased electrode, and a ground ring are all present at a building, what must be done?

All of them must be bonded together into one grounding electrode system
Only the water pipe may be used; the others may be ignored
Only one electrode of the installer's choosing needs to be connected
Each electrode must serve a separate, unconnected system

NEC Reference: NEC 250.50

Question 28: Per NEC Table 250.66, a service has 1/0 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)?

8 AWG copper
6 AWG copper
4 AWG copper
2 AWG copper

NEC Reference: NEC Table 250.66

Question 29: Per NEC 250.66(A), when the grounding electrode conductor connects only to a rod, pipe, or plate electrode, it is not required to be larger than what size copper conductor, no matter how large the service conductors are?

3/0 AWG copper
6 AWG copper
2 AWG copper
1/0 AWG copper

NEC Reference: NEC 250.66(A)

Question 30: Per NEC 240.24(D), overcurrent protective devices shall not be located in the vicinity of _____ .

Bathrooms only
Easily ignitible material, such as in clothes closets
Outdoor equipment only
Any location above 6 feet

NEC Reference: NEC 240.24(D)

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 6

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NEC 2020 Journeyman Practice Test 6

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NEC 2020 Journeyman Practice Test 6 — Question List

Question 1: At service equipment, the main bonding jumper connects the grounded (neutral) conductor to which of the following?

Question 2: Which of the following is specifically prohibited from being used as a grounding electrode?

Question 3: Per NEC Table 250.66, for a service with copper ungrounded conductors of 2 AWG or smaller, what is the minimum size copper grounding electrode conductor (GEC)?

Question 4: Per NEC 250.53(A)(2), a single rod, pipe, or plate electrode with a resistance to earth greater than _____ ohms must be supplemented with an additional electrode.

Question 5: A concrete-encased electrode (Ufer ground) using bare copper conductor must be at least how long to qualify as a grounding electrode?

Question 6: A ground ring grounding electrode must consist of at least 20 feet of bare copper conductor not smaller than _____ encircling the building.

Question 7: A driven ground rod electrode must have a minimum length of at least how many feet in contact with the soil?

Question 8: Per NEC 250.53(A)(3), when two rod electrodes are used, they must be spaced not less than _____ apart to be effective.

Question 9: Per NEC Table 250.122, what is the minimum size copper equipment grounding conductor (EGC) required for a circuit protected by a 20 ampere overcurrent device?

Question 10: A feeder is protected by a 100 ampere circuit breaker. Per NEC Table 250.122, what is the minimum size copper equipment grounding conductor required?

Question 11: Downstream of the service disconnecting means, which of the following is generally NOT a recognized equipment grounding conductor?

Question 12: Per NEC 250.104(B), metal piping systems (such as gas piping) that may become energized must be bonded to which of the following?

Question 13: For a separately derived system, such as a dry-type transformer secondary, where may the required system bonding jumper be installed per NEC 250.30(A)(1)?

Question 14: A feeder supplies a disconnecting means at a separate structure on the same property. Per NEC 250.32(B)(1), what is required at the structure regarding grounding?

Question 15: Grounding and bonding connections must be made in a way that does NOT create what condition, per NEC 250.6(A)?

Question 16: Unless a specific exception applies, what is the maximum standard overcurrent protection permitted for a 12 AWG copper conductor?

Question 17: Unless a specific exception applies, what is the maximum standard overcurrent protection permitted for a 10 AWG copper conductor?

Question 18: A continuous load calculation results in a required conductor ampacity of 34 amperes, which is not a standard overcurrent device size. Per NEC 240.4(B) and 240.6(A), what should be done?

Question 19: Under the 10-foot tap rule of NEC 240.21(B)(1), which of the following is a required condition?

Question 20: Under the 25-foot tap rule of NEC 240.21(B)(2), the tap conductors must have an ampacity of at least what fraction of the rating of the overcurrent device from which they are tapped?

Question 21: True or false: NEC 240.24(E) prohibits installing overcurrent devices, such as panelboards, in the bathrooms of dwelling units.

Question 22: Per the 2020 NEC Table 310.15(B)(16), what is the allowable ampacity of an 8 AWG copper conductor with 90°C insulation (such as THHN), in a raceway with no more than 3 current-carrying conductors at 30°C ambient?

Question 23: Per the 2020 NEC Table 310.15(B)(16), what is the allowable ampacity of a 6 AWG copper conductor with 90°C insulation, in a raceway with no more than 3 current-carrying conductors at 30°C ambient?

Question 24: A branch circuit uses 10 AWG copper THHN conductors. Table 310.15(B)(16) lists a 90°C ampacity of 40 amperes for this conductor, but what is the maximum standard breaker size actually permitted to protect it?

Question 25: Per NEC 310.15(B)(3)(a), when a raceway or cable contains 4 through 6 current-carrying conductors, the table ampacity of each conductor must be adjusted to what percentage?

Question 26: Per NEC 250.24(A)(5), on the load side of the service disconnecting means, the grounded (neutral) conductor must:

Question 27: Per NEC 250.50, if a metal underground water pipe, a concrete-encased electrode, and a ground ring are all present at a building, what must be done?

Question 28: Per NEC Table 250.66, a service has 1/0 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)?

Question 29: Per NEC 250.66(A), when the grounding electrode conductor connects only to a rod, pipe, or plate electrode, it is not required to be larger than what size copper conductor, no matter how large the service conductors are?

Question 30: Per NEC 240.24(D), overcurrent protective devices shall not be located in the vicinity of _____ .

Key NEC References for This Test

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