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NEC CODE NEC 2023

Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2023 Edition

Free NEC 2023 practice test on cabinets, enclosures, and boxes. Covers box fill volume calculations, splices and taps in enclosures, and which items count toward box fill. Simple English, full explanations.

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The National Electrical Code (NFPA 70) is the benchmark standard for safe electrical installation in the US. It is updated every 3 years by the NFPA.

Study the edition adopted by your state. As of 2025, most states use the 2020 or 2023 NEC. These tests are written to the 2023 edition.

The most tested articles are 100 (Definitions), 200–250 (Wiring & Grounding), 300–314 (Wiring Methods), 400–411 (Conductors), 430 (Motors), and 700–701 (Emergency Systems).

How to Use This Practice Test

This Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2023 Edition 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: Use the NEC index (back of the book) — find answers by keyword, not by article number.

Topics covered: NEC articles 100, 210, 220, 240, 250, 300, 310, 430, and special occupancies.
Passing score: Aim for 80%+ on NEC code tests before exam day.
Questions: 30 multiple-choice, one correct answer each

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Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2023 Edition — Question List

Question 1: What is the minimum box fill volume allowance required for each 16 AWG conductor?

1.75 cubic inches
2.0 cubic inches
2.25 cubic inches
2.5 cubic inches

NEC Reference: NEC Table 314.16(B)

Question 2: True or false: a cabinet or enclosure can never be used as a raceway for conductors passing through it.

True
False
Only for metal enclosures
Only underground

NEC Reference: NEC 312.8

Question 3: Splices and taps can be installed in a cabinet or enclosure used as a raceway if they do not fill more than what percent of the cross-sectional area at that point?

NEC Reference: NEC 312.8

Question 4: True or false: locknuts, bushings, AND internal cable clamps are all excluded from box fill volume calculations.

True
False
Only for plastic boxes
Only for metal boxes

NEC Reference: NEC 314.16(B)

Question 5: Which of the following conductors is NOT counted for box fill calculations?

Conductors that originate and terminate entirely within the box
A conductor loop less than 12 inches long that enters the box
A conductor that terminates in the box
A conductor that passes through the box

NEC Reference: NEC 314.16(B)(1)

Question 6: A junction box contains two receptacles, four 12 AWG circuit conductors, and two 12 AWG equipment grounding conductors. What is the total required box fill volume?

20.25 cu in
22.50 cu in
18 cu in
24.75 cu in

NEC Reference: NEC 314.16 / Table 314.16(B)

Question 7: A box has 14.40 cubic inches of remaining volume after devices are accounted for. How many additional 14 AWG conductors can be added?

NEC Reference: NEC Table 314.16(B)

Question 8: How many 10 AWG conductors can be spliced within an 11 cubic inch conduit body?

NEC Reference: NEC Table 314.16(B)

Question 9: A box is generally required at each termination point for which type of wiring?

Power and lighting systems
Communication systems
Control conductors only
Signaling conductors only

NEC Reference: NEC 300.15

Question 10: A 3-wire, single-phase, 120/240-volt circuit supplies a 1,000 W, 120-volt electric heater and a 600 W, 120-volt electric dryer on the opposite leg. What is the operating voltage of the heater?

90 volts
100 volts
120 volts
110 volts

NEC Reference: General electrical theory (series circuit with two different loads)

Question 11: For box fill calculations, a single device (like a switch or receptacle) mounted on one strap counts as how many conductor-equivalents?

Two
Zero
One
Three

NEC Reference: NEC 314.16(B)(4)

Question 12: When one or more equipment grounding conductors enter a box, how many conductor-equivalents are counted for box fill?

One, for the whole group
One for each equipment grounding conductor
Zero -- they are never counted
Two for each conductor

NEC Reference: NEC 314.16(B)(5)

Question 13: What is the box fill volume allowance required for each 8 AWG conductor?

3.00 cubic inches
2.50 cubic inches
2.00 cubic inches
3.50 cubic inches

NEC Reference: NEC Table 314.16(B)

Question 14: What is the box fill volume allowance required for each 18 AWG conductor?

1.50 cubic inches
1.75 cubic inches
2.00 cubic inches
1.25 cubic inches

NEC Reference: NEC Table 314.16(B)

Question 15: Metal boxes must generally be durably and legibly marked with what, to help with box fill calculations?

Their cubic inch capacity
Nothing is required
Only the manufacturer's logo
Only the color

NEC Reference: NEC 314.16(A)(2)

Question 16: For a straight pull in a pull box, the box length must generally be at least what multiple of the largest raceway's trade diameter?

8 times
4 times
6 times
10 times

NEC Reference: NEC 314.28(A)(1)

Question 17: For an angle or U-pull in a pull box, the distance between raceway entries enclosing the same conductor must generally be at least what multiple of the raceway trade diameter?

6 times
8 times
4 times
10 times

NEC Reference: NEC 314.28(A)(2)

Question 18: Outlet, device, pull, and junction boxes must generally be installed so as to be what, after the building is finished?

Accessible without removing building finish
Permanently sealed behind drywall
Buried with no access at all
Removed after construction

NEC Reference: NEC 314.29

Question 19: A domed or raised box cover can generally add to the box's usable fill volume if what condition is met?

The cover is marked with its volume
Any cover always counts, marked or not
Covers never add volume
Only plastic covers count

NEC Reference: NEC 314.16(A)(2)

Question 20: Fittings used with cabinets and cutout boxes, such as connectors and locknuts, must generally be what?

Listed and used per their listing
Homemade only
Unlisted is preferred
Nothing is required

NEC Reference: NEC 110.3(B)

Question 21: What is the box fill volume allowance required for each 6 AWG conductor?

5.00 cubic inches
4.00 cubic inches
3.50 cubic inches
6.00 cubic inches

NEC Reference: NEC Table 314.16(B)

Question 22: A box contains 6 current-carrying 14 AWG conductors and one duplex receptacle (a single device). What is the total required box fill volume?

16 cubic inches
12 cubic inches
14 cubic inches
18 cubic inches

NEC Reference: NEC 314.16 / Table 314.16(B)

Question 23: For a nonmetallic box with integral (built-in) cable clamps, how are those clamps generally counted in box fill?

One conductor-equivalent for the whole box
One for each individual clamp
They are never counted
Two for each clamp

NEC Reference: NEC 314.16(B)(2)

Question 24: An outlet box used to support a ceiling-suspended paddle fan must generally be what?

Listed for fan support
Any general-purpose box
A cardboard box
Not required to hold any weight

NEC Reference: NEC 314.27(C)

Question 25: An outlet box used to support a luminaire weighing more than 50 pounds must generally be what?

Listed and marked for that weight
Made of plastic with no rating
Ignored, weight does not matter
Removed completely

NEC Reference: NEC 314.27(A)(2)

Question 26: Per NEC Article 100 definitions, what generally distinguishes a "cutout box" from a "cabinet"?

A cutout box is surface-mounted only
There is no difference at all
A cutout box is always underground
A cabinet is always outdoors

NEC Reference: NEC Article 100

Question 27: Support fittings, such as fixture studs or hickeys that take up space in a box, are generally treated in box fill calculations similar to what other item?

A cable clamp
A locknut
A bushing
Nothing -- it is never counted

NEC Reference: NEC 314.16(B)(3)

Question 28: A cabinet or cutout box installed outdoors or in a wet location must generally be what?

Weatherproof
Left uncovered
Made only of untreated wood
Nothing special is required

NEC Reference: NEC 312.2(A)

Question 29: A standard single-gang device box with 18 cubic inches of volume, containing one duplex receptacle and 3 current-carrying 12 AWG conductors, plus 1 equipment grounding conductor -- is this box fill compliant?

Yes, 13.5 cu in is required, which fits
No, it exceeds 18 cu in
It requires exactly 18 cu in, no margin
Box fill does not apply to device boxes

NEC Reference: NEC 314.16

Key NEC References for This Test

Article	What It Covers
Ch. 1–4	General rules — apply to all installations
Ch. 5–7	Special rules — override Ch. 1–4 where they conflict
Ch. 8	Communications — completely independent of Ch. 1–7
Ch. 9	Tables — referenced by articles, not standalone enforceable rules
Art. 210.12	AFCI — major expansion in NEC 2026
Art. 230.67	Surge protection at service equipment — new NEC 2026

Study Tip: Learn the NEC index — use keywords, not article numbers. Practice finding 5 different topics in under 2 minutes each.

Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2023 Edition

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Key NEC References for This Test

Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2023 Edition

How this test works

Frequently Asked Questions

Is this Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2023 Edition free?

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What articles are covered on electrician licensing exams?

How to Use This Practice Test

Student Reviews

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Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2023 Edition — Question List

Question 1: What is the minimum box fill volume allowance required for each 16 AWG conductor?

Question 2: True or false: a cabinet or enclosure can never be used as a raceway for conductors passing through it.

Question 3: Splices and taps can be installed in a cabinet or enclosure used as a raceway if they do not fill more than what percent of the cross-sectional area at that point?

Question 4: True or false: locknuts, bushings, AND internal cable clamps are all excluded from box fill volume calculations.

Question 5: Which of the following conductors is NOT counted for box fill calculations?

Question 6: A junction box contains two receptacles, four 12 AWG circuit conductors, and two 12 AWG equipment grounding conductors. What is the total required box fill volume?

Question 7: A box has 14.40 cubic inches of remaining volume after devices are accounted for. How many additional 14 AWG conductors can be added?

Question 8: How many 10 AWG conductors can be spliced within an 11 cubic inch conduit body?

Question 9: A box is generally required at each termination point for which type of wiring?

Question 10: A 3-wire, single-phase, 120/240-volt circuit supplies a 1,000 W, 120-volt electric heater and a 600 W, 120-volt electric dryer on the opposite leg. What is the operating voltage of the heater?

Question 11: For box fill calculations, a single device (like a switch or receptacle) mounted on one strap counts as how many conductor-equivalents?

Question 12: When one or more equipment grounding conductors enter a box, how many conductor-equivalents are counted for box fill?

Question 13: What is the box fill volume allowance required for each 8 AWG conductor?

Question 14: What is the box fill volume allowance required for each 18 AWG conductor?

Question 15: Metal boxes must generally be durably and legibly marked with what, to help with box fill calculations?

Question 16: For a straight pull in a pull box, the box length must generally be at least what multiple of the largest raceway's trade diameter?

Question 17: For an angle or U-pull in a pull box, the distance between raceway entries enclosing the same conductor must generally be at least what multiple of the raceway trade diameter?

Question 18: Outlet, device, pull, and junction boxes must generally be installed so as to be what, after the building is finished?

Question 19: A domed or raised box cover can generally add to the box's usable fill volume if what condition is met?

Question 20: Fittings used with cabinets and cutout boxes, such as connectors and locknuts, must generally be what?

Question 21: What is the box fill volume allowance required for each 6 AWG conductor?

Question 22: A box contains 6 current-carrying 14 AWG conductors and one duplex receptacle (a single device). What is the total required box fill volume?

Question 23: For a nonmetallic box with integral (built-in) cable clamps, how are those clamps generally counted in box fill?

Question 24: An outlet box used to support a ceiling-suspended paddle fan must generally be what?

Question 25: An outlet box used to support a luminaire weighing more than 50 pounds must generally be what?

Question 26: Per NEC Article 100 definitions, what generally distinguishes a "cutout box" from a "cabinet"?

Question 27: Support fittings, such as fixture studs or hickeys that take up space in a box, are generally treated in box fill calculations similar to what other item?

Question 28: A cabinet or cutout box installed outdoors or in a wet location must generally be what?

Question 29: A standard single-gang device box with 18 cubic inches of volume, containing one duplex receptacle and 3 current-carrying 12 AWG conductors, plus 1 equipment grounding conductor -- is this box fill compliant?

Key NEC References for This Test

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