Previous Branch Circuits (NEC 210) — NEC 2023 Edition Next Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2023 Edition

NEC CODE NEC 2020

Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2020 Edition

Free NEC 2020 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.

TOPICS COVERED

NEC Practice Tests

How this test works

Read each question carefully

Look for absolute words like always / never — they often distinguish the right answer.

Manage your time

You have 45 min for 30 questions. Skip tough ones and come back.

Progress is auto-saved

Your answers are saved locally — a page refresh won't lose your work.

Review your answers

After submitting you'll see every explanation and your NEC references.

Frequently Asked Questions

Yes — free, no signup required. Each question links to the relevant NEC article so you can study the code directly.

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 2020 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

Questions

45 min

Time

70%

Pass

Timer starts immediately. Progress is auto-saved.

Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2020 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: Conductors pass through a cabinet that is being used as a raceway. Their total cross-sectional area at any point may not exceed what percentage of the cabinet cross-section?

NEC Reference: NEC 312.8(A)

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: Which of the following IS counted in a box fill calculation?

Internal cable clamps
A pigtail that starts and ends inside the box
Locknuts
Bushings

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 device box contains six 12 AWG conductors, two 12 AWG equipment grounding conductors, internal cable clamps and one receptacle. What minimum box volume is required?

18.00 cubic inches
20.25 cubic inches
22.50 cubic inches
24.75 cubic inches

NEC Reference: NEC 314.16(B)

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: Per the 2020 NEC, six equipment grounding conductors (all 12 AWG) enter a box. How many volume allowances are counted for them?

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: A device box is installed in a ceramic tile (noncombustible) wall. How far may the front edge of the box be set back from the finished surface?

Not more than ¼ in.
It must be flush or project
Not more than 1/8 in.
Not more than ½ in.

NEC Reference: NEC 314.20

Question 15: Boxes of 100 cubic inches or less that are not listed in Table 314.16(A) must be durably and legibly marked with what?

Their trade size only
The maximum number of devices
The largest conductor size allowed
Their volume in cubic inches

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 be installed so that the wiring in them can be reached how?

Only from an attic or crawl space
By removing a section of drywall
Only by a qualified person with special tools
Without removing any part of the building finish

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: Connectors, locknuts and other fittings used with cabinets and boxes must be installed how?

Only with an extra locknut on every fitting
In accordance with their listing and labeling
Only as directed by the inspector on site
In any way that holds the cable firmly

NEC Reference: NEC 110.3(B)

Question 21: Several NM cables enter the top of a surface-mounted cabinet through one nonflexible raceway sleeve under the 312.5(C) exception. What length is the raceway permitted to be?

At least 18 in. but not more than 10 ft
At least 6 in. but not more than 3 ft
Any length, if the raceway is metal
At least 3 ft but not more than 20 ft

NEC Reference: NEC 312.5(C)

Question 22: A box contains 6 current-carrying 14 AWG conductors and one duplex receptacle. 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 that is the sole support for a ceiling-suspended paddle fan must be what?

Any metal box fastened with two screws
A nonmetallic box with a fan brace sticker
Listed and marked as suitable for fan support
A box listed for luminaires up to 50 lb

NEC Reference: NEC 314.27(C)

Question 25: A ceiling outlet box will support a luminaire weighing more than 50 lb. What does the NEC require?

The box must be listed and marked for the weight supported
Any box with 10-32 screws is acceptable
A nonmetallic box of any rating may be used
The luminaire canopy alone must carry the load

NEC Reference: NEC 314.27(A)(2)

Question 26: According to the Article 100 definitions, what distinguishes a cutout box from a cabinet?

A cabinet never has a door
A cutout box is designed for surface mounting only
A cutout box is designed for flush mounting only
A cutout box may not contain overcurrent devices

NEC Reference: NEC Article 100

Question 27: How are support fittings such as fixture studs and hickeys counted in box fill?

Two volume allowances for each fitting
They are counted only in metal boxes
One volume allowance for each type of fitting
They are not counted

NEC Reference: NEC 314.16(B)(3)

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

Raintight at the top only
Coated with a rust inhibitor only
Flush-mounted in the wall
Weatherproof

NEC Reference: NEC 312.2

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

Question 30: A circuit is protected by a 30-ampere overcurrent device. What is the minimum size copper equipment grounding conductor required in the box?

10 AWG
12 AWG
14 AWG
8 AWG

NEC Reference: NEC Table 250.122

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 2020 Edition

How this test works

Frequently Asked Questions

How to Use This Practice Test

Electrician Reviews

Leave a Review

Key NEC References for This Test

Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2020 Edition

How this test works

Frequently Asked Questions

Is this Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2020 Edition free?

What is the NEC code book?

Which NEC edition should I study?

What articles are covered on electrician licensing exams?

How to Use This Practice Test

Challenge your friends

Electrician Reviews

Leave a Review

Cabinets, Enclosures & Cutout Boxes (NEC 312/314) — NEC 2020 Edition — Question List

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

Question 2: Conductors pass through a cabinet that is being used as a raceway. Their total cross-sectional area at any point may not exceed what percentage of the cabinet cross-section?

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: Which of the following IS counted in a box fill calculation?

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 device box contains six 12 AWG conductors, two 12 AWG equipment grounding conductors, internal cable clamps and one receptacle. What minimum box volume is required?

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: Per the 2020 NEC, six equipment grounding conductors (all 12 AWG) enter a box. How many volume allowances are counted for them?

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

Question 14: A device box is installed in a ceramic tile (noncombustible) wall. How far may the front edge of the box be set back from the finished surface?

Question 15: Boxes of 100 cubic inches or less that are not listed in Table 314.16(A) must be durably and legibly marked with what?

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 be installed so that the wiring in them can be reached how?

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: Connectors, locknuts and other fittings used with cabinets and boxes must be installed how?

Question 21: Several NM cables enter the top of a surface-mounted cabinet through one nonflexible raceway sleeve under the 312.5(C) exception. What length is the raceway permitted to be?

Question 22: A box contains 6 current-carrying 14 AWG conductors and one duplex receptacle. 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 that is the sole support for a ceiling-suspended paddle fan must be what?

Question 25: A ceiling outlet box will support a luminaire weighing more than 50 lb. What does the NEC require?

Question 26: According to the Article 100 definitions, what distinguishes a cutout box from a cabinet?

Question 27: How are support fittings such as fixture studs and hickeys counted in box fill?

Question 28: A cabinet or cutout box installed in a wet location must 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?

Question 30: A circuit is protected by a 30-ampere overcurrent device. What is the minimum size copper equipment grounding conductor required in the box?

Key NEC References for This Test

Related Practice Tests