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NEC 2020 Code Questions Practice Test 16

Free NEC 2020 practice test with 30 questions on conductor sizing, feeder taps, cable types, and motor circuits. Plain-English questions with full explanations.

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This NEC 2020 Code Questions Practice Test 16 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: Mixed-format test — questions jump between topics just like the real exam. Don't spend more than 90 seconds on any one question.

Topics covered: All NEC chapters — branch circuits, grounding, conductors, wiring methods, motors, and more.
Passing score: Aim for 80%+ consistently before scheduling your exam.
Questions: 30 multiple-choice, one correct answer each

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NEC 2020 Code Questions Practice Test 16 — Question List

Question 1: Where the grounding electrode conductor connects only to a concrete-encased electrode, it need not be larger than:

4 AWG copper
2/0 AWG copper
14 AWG copper
There is no maximum

NEC Reference: NEC 250.66(B)

Question 2: Where the grounding electrode conductor connects only to a rod electrode, it need not be larger than:

6 AWG copper
2 AWG copper
14 AWG copper
There is no maximum

NEC Reference: NEC 250.66(A)

Question 3: What is the maximum standard overcurrent device rating for a 12 AWG copper conductor?

15 amperes
20 amperes
25 amperes
30 amperes

NEC Reference: NEC 240.4(D)(5)

Question 4: What is the maximum standard overcurrent device rating for a 10 AWG copper conductor?

20 amperes
25 amperes
30 amperes
40 amperes

NEC Reference: NEC 240.4(D)(7)

Question 5: What is the maximum standard overcurrent device rating for a 16 AWG copper fixture wire?

7 amperes
10 amperes
15 amperes
20 amperes

NEC Reference: NEC 240.4(D)(2)

Question 6: Under the 25-foot tap rule, the tap conductor ampacity must be at least what fraction of the feeder overcurrent device rating?

One-tenth
One-third
One-half
Full rating

NEC Reference: NEC 240.21(B)(2)

Question 7: Under the 10-foot tap rule, tap conductors can skip overcurrent protection at the tap point if they are not longer than:

10 feet
25 feet
50 feet
100 feet

NEC Reference: NEC 240.21(B)(1)

Question 8: As a general rule, overcurrent protection is placed at the point where a conductor:

Receives its supply
Ends at the last outlet
Crosses a property line
There is no general rule

NEC Reference: NEC 240.21

Question 9: Which of the following is a standard fuse and breaker rating?

45 amperes
48 amperes
52 amperes
58 amperes

NEC Reference: NEC 240.6(A)

Question 10: A panelboard circuit directory must be:

Legible and clear
Handwritten in pencil only
Not required
Written in a foreign language only

NEC Reference: NEC 408.4(A)

Question 11: A 4 inch round box, 1 1/2 inches deep, has a listed volume of:

12.5 cubic inches
15.5 cubic inches
18 cubic inches
21 cubic inches

NEC Reference: NEC Table 314.16(A)

Question 12: NM cable (Romex) is not permitted to be:

Embedded in poured concrete
Used in a wall cavity
Fished through a finished wall
Run in an attic

NEC Reference: NEC 334.12

Question 13: Type AC cable has an internal bonding strip in contact with the armor. This strip is used to:

Give a backup grounding path
Add insulation only
Improve color coding
It has no purpose

NEC Reference: NEC 320.108

Question 14: Type SE (service entrance) cable ampacity is based on the:

60 C column
90 C column
It has no ampacity
30 C column

NEC Reference: NEC 338.10

Question 15: For sizing motor conductors, the full-load current value used should come from:

The NEC full-load current tables
The nameplate current, always
A guess
The panel rating

NEC Reference: NEC 430.6(A)(1)

Question 16: A motor has a full-load current of 12 amperes. What is the minimum branch-circuit conductor ampacity?

12 amperes
15 amperes
18 amperes
24 amperes

NEC Reference: NEC 430.22(A)

Question 17: A 3/4 horsepower motor normally runs unattended and is not readily accessible. What can serve as its overload protection?

The branch-circuit overcurrent device
Nothing, protection is skipped
A padlock
A separate 400% fuse only

NEC Reference: NEC 430.32(B)

Question 18: Under the 25-foot transformer secondary tap rule, the tap conductors must be protected from physical damage and be no longer than:

10 feet
25 feet
50 feet
100 feet

NEC Reference: NEC 240.21(C)(6)

Question 19: An autotransformer supplying a branch circuit needs overcurrent protection set at not more than what percent of the rated input current?

125 %
250 %
400 %
No protection is needed

NEC Reference: NEC 450.4

Question 20: Dry-type transformer vent openings must not be blocked by:

Walls or other obstructions
Nothing, blocking is fine
Paint only
It does not matter

NEC Reference: NEC 450.9

Question 21: A receptacle for servicing HVAC equipment must be within what distance of the equipment?

10 feet
25 feet
50 feet
100 feet

NEC Reference: NEC 210.63

Question 22: NEC 210.8 is split into two parts. What do these two parts cover?

Dwelling units and other than dwelling units
Only dwelling units
Only commercial buildings
Nothing, both parts are the same

NEC Reference: NEC 210.8

Question 23: AFCI protection also applies to guest rooms in:

Hotels and motels
Warehouses only
No other occupancy
Parking lots only

NEC Reference: NEC 210.12(C)

Question 24: Which of these is an accepted reason for a building to have more than one service?

A fire pump
A ceiling fan
A toaster
A lamp

NEC Reference: NEC 230.2(A)

Question 25: Which of these can be connected ahead of (supply side of) the service disconnect?

A listed surge-protective device
A lighting panel
A branch-circuit receptacle
A motor circuit

NEC Reference: NEC 230.82

Question 26: For a grounded conductor larger than 6 AWG, identification is permitted at the time of installation by:

White tape or paint at each end
No marking at all
A red marking only
A metal tag with no color

NEC Reference: NEC 200.6(B)

Question 27: A service raceway has 2/0 AWG copper conductors. What size copper supply-side bonding jumper is needed?

8 AWG
4 AWG
1/0 AWG
3/0 AWG

NEC Reference: NEC 250.102(C)

Question 28: Where several service disconnects are used, the grounding electrode conductor can be run as one common conductor with:

Taps run to each disconnect
No taps at all, ever
A separate rod for each disconnect only
It is never permitted

NEC Reference: NEC 250.64(D)

Question 29: The size of the supply-side bonding jumper is generally based on the size of the:

Largest ungrounded service conductor
Building square footage
Number of light fixtures
Roof height

NEC Reference: NEC 250.102(C)

Question 30: Why must the grounded (neutral) conductor be run to each service disconnecting means?

It is part of the ground-fault current path
It has no real purpose
To save on copper
For looks only

NEC Reference: NEC 250.24(C)

NEC 2020 Code Questions Practice Test 16

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NEC 2020 Code Questions Practice Test 16

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Student Reviews

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NEC 2020 Code Questions Practice Test 16 — Question List

Question 1: Where the grounding electrode conductor connects only to a concrete-encased electrode, it need not be larger than:

Question 2: Where the grounding electrode conductor connects only to a rod electrode, it need not be larger than:

Question 3: What is the maximum standard overcurrent device rating for a 12 AWG copper conductor?

Question 4: What is the maximum standard overcurrent device rating for a 10 AWG copper conductor?

Question 5: What is the maximum standard overcurrent device rating for a 16 AWG copper fixture wire?

Question 6: Under the 25-foot tap rule, the tap conductor ampacity must be at least what fraction of the feeder overcurrent device rating?

Question 7: Under the 10-foot tap rule, tap conductors can skip overcurrent protection at the tap point if they are not longer than:

Question 8: As a general rule, overcurrent protection is placed at the point where a conductor:

Question 9: Which of the following is a standard fuse and breaker rating?

Question 10: A panelboard circuit directory must be:

Question 11: A 4 inch round box, 1 1/2 inches deep, has a listed volume of:

Question 12: NM cable (Romex) is not permitted to be:

Question 13: Type AC cable has an internal bonding strip in contact with the armor. This strip is used to:

Question 14: Type SE (service entrance) cable ampacity is based on the:

Question 15: For sizing motor conductors, the full-load current value used should come from:

Question 16: A motor has a full-load current of 12 amperes. What is the minimum branch-circuit conductor ampacity?

Question 17: A 3/4 horsepower motor normally runs unattended and is not readily accessible. What can serve as its overload protection?

Question 18: Under the 25-foot transformer secondary tap rule, the tap conductors must be protected from physical damage and be no longer than:

Question 19: An autotransformer supplying a branch circuit needs overcurrent protection set at not more than what percent of the rated input current?

Question 20: Dry-type transformer vent openings must not be blocked by:

Question 21: A receptacle for servicing HVAC equipment must be within what distance of the equipment?

Question 22: NEC 210.8 is split into two parts. What do these two parts cover?

Question 23: AFCI protection also applies to guest rooms in:

Question 24: Which of these is an accepted reason for a building to have more than one service?

Question 25: Which of these can be connected ahead of (supply side of) the service disconnect?

Question 26: For a grounded conductor larger than 6 AWG, identification is permitted at the time of installation by:

Question 27: A service raceway has 2/0 AWG copper conductors. What size copper supply-side bonding jumper is needed?

Question 28: Where several service disconnects are used, the grounding electrode conductor can be run as one common conductor with:

Question 29: The size of the supply-side bonding jumper is generally based on the size of the:

Question 30: Why must the grounded (neutral) conductor be run to each service disconnecting means?

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