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Equipment for General Use (NEC 400/402/408/424/440/480) — NEC 2023 Edition

Free NEC 2023 practice test on general-use equipment rules: flexible cords, fixture wires, panelboards, air-conditioning branch circuits, transformer vaults, fixed electric space heating, and storage batteries. 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 Equipment for General Use (NEC 400/402/408/424/440/480) — 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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Equipment for General Use (NEC 400/402/408/424/440/480) — NEC 2023 Edition — Question List

Question 1: What is the smallest fixture wire size permitted by the NEC?

16 AWG
18 AWG
20 AWG
22 AWG

NEC Reference: NEC 402.6

Question 2: Where must the disconnecting means for air-conditioning or refrigerating equipment be located?

Within 100 ft of the equipment
At the service equipment only
Anywhere in the same building
Within sight from, and readily accessible from, the equipment

NEC Reference: NEC 440.14

Question 3: Two cord-and-plug-connected room air conditioners are the only loads on a 30-ampere branch circuit. What is the maximum total marked rating of the two units?

15 amperes
24 amperes
27 amperes
30 amperes

NEC Reference: NEC 440.62(B)

Question 4: A transformer vault is protected by an automatic sprinkler system. What minimum fire rating is permitted for the vault doorway?

1 hour
3 hours
1/2 hour
2 hours

NEC Reference: NEC 450.43(A)

Question 5: Ground-fault protection of equipment is provided for an impedance heating system. What is the maximum transformer secondary voltage permitted?

30 volts
80 volts
65 volts
50 volts

NEC Reference: NEC 426.32

Question 6: How must fixed outdoor electric deicing and snow-melting equipment be treated when sizing its branch circuit?

continuous load
Non continuous load
Heavy load
Not important load for service conductor calculations

NEC Reference: NEC 426.4

Question 7: Which of the following is an allowable ampacity of an 10 AWG fixture wire?

23 amp
17 amp
28 amp
30 amp

NEC Reference: NEC Table 402.5

Question 8: According to the Article 100 definition of nominal voltage, what is the nominal voltage of a lead-acid cell?

2 volts
1.2 volts
1.7 volts
2.2 volts

NEC Reference: NEC Article 100

Question 9: A disconnecting means for a motor circuit rated 1000 volts or less must have an ampere rating of at least what?

150% of the motor full-load current
125% of the motor full-load current
115% of the motor full-load current
100% of the motor full-load current

NEC Reference: NEC 430.110(A)

Question 10: A branch circuit supplies two or more outlets for fixed electric space-heating equipment. Which rating is NOT permitted for that circuit?

15 amperes
20 amperes
30 amperes
40 amperes

NEC Reference: NEC Article 424

Question 11: A flexible cord generally cannot be used as a substitute for what?

The fixed wiring of a structure
A portable lamp cord
An extension cord
A tool cord

NEC Reference: NEC 400.12

Question 12: What does 408.36(C) say about delta breakers?

They may be back-fed if secured
They must be marked SWD
They may be used only in dwelling units
They shall not be installed in panelboards

NEC Reference: NEC 408.36(C)

Question 13: A single cord-and-plug window air conditioner is supplied by a 15-ampere branch circuit. What is the maximum full-load current rating permitted for that unit?

12 amperes
15 amperes
10 amperes
18 amperes

NEC Reference: NEC 440.62(B)

Question 14: If a transformer vault doorway is NOT protected by an automatic sprinkler or water spray system, what fire rating does it generally require, versus the 1-hour rating used when sprinklers ARE present?

A higher rating (typically 3 hours)
The same 1-hour rating
No fire rating is ever required
Exactly half an hour

NEC Reference: NEC 450.43

Question 15: An impedance heating system is NOT protected by ground-fault protection of equipment. What is the maximum transformer secondary voltage permitted?

30 volts
50 volts
80 volts
120 volts

NEC Reference: NEC 426.32

Question 16: What is the general definition of a "continuous load" under the NEC?

Maximum current expected to continue for 3 hours or more
Any load running for more than 10 minutes
Any load over 50 amperes
Only loads running 24 hours a day

NEC Reference: NEC Article 100

Question 17: What is the allowable ampacity of a 14 AWG fixture wire according to Table 402.5?

8 amperes
15 amperes
17 amperes
20 amperes

NEC Reference: NEC Table 402.5

Question 18: According to the Article 100 definition of nominal voltage, what is the nominal voltage of an alkali (nickel-cadmium) cell?

1.2 volts
2 volts
3.6 volts
1.5 volts

NEC Reference: NEC Article 100

Question 19: A 300-volt motor has a full-load current of 40 amperes. What is the minimum ampere rating generally required for its disconnecting means?

46 amperes
40 amperes
50 amperes
60 amperes

NEC Reference: NEC 430.110

Question 20: Branch circuits supplying two or more outlets for fixed electric space-heating equipment must be rated at which values?

15, 20, 25, or 30 amperes
15, 20, 30, or 40 amperes
20, 30, 40, or 50 amperes
Any rating is permitted with no limit

NEC Reference: NEC Article 424

Question 21: According to the informational note to the Article 100 definition of nominal voltage, what is the nominal voltage of a lithium-ion cell?

About 3.6-3.8 volts
2 volts
1.2 volts
12 volts

NEC Reference: NEC Article 100

Question 22: What does the term "dusttight" mean in the NEC?

Dust will not enter the enclosure under specified test conditions
The enclosure can contain an internal explosion
The enclosure is sealed with silicone at every seam
The enclosure keeps out water under a hose stream

NEC Reference: NEC Article 100

Question 23: A cord-and-plug-connected room air conditioner is on a 20-ampere branch circuit that also supplies lighting outlets. What is the maximum rating of the air conditioner?

8 amperes
10 amperes
16 amperes
20 amperes

NEC Reference: NEC 440.62(C)

Question 24: Because fixed outdoor deicing and snow-melting equipment is treated as a continuous load, its branch-circuit conductors and overcurrent protection are generally sized at not less than what percentage of the load current?

125%
100%
80%
150%

NEC Reference: NEC 426.4

Question 25: Table 402.5 lists the allowable ampacity of fixture wires based on what?

The AWG size of the fixture wire
The wattage of the luminaire
The length of the run
The color of the insulation

NEC Reference: NEC Table 402.5

Question 26: Panelboards must be of what type of construction?

Live-front
Open-frame
Dead-front
Front-connected only

NEC Reference: NEC 408.38

Question 27: What protection must be provided for the branch circuit supplying fixed outdoor electric deicing and snow-melting equipment?

Ground-fault protection of equipment (GFPE)
No protection is required
Only a fuse, no GFCI/GFPE
Only a disconnect switch

NEC Reference: NEC 426.28

Question 28: Storage battery installations that can produce hydrogen gas generally require what, per NEC Article 480?

Ventilation to prevent hydrogen gas accumulation
No special provisions are ever needed
A fire sprinkler only
A dedicated 20A receptacle only

NEC Reference: NEC Article 480

Question 29: How must the personnel doors of a transformer vault open, and what hardware do they need?

Open either way, with no special hardware
Open outward in the direction of egress, with listed panic hardware
Slide sideways, with a keyed latch
Open inward, with a keyed deadbolt

NEC Reference: NEC 450.43(C)

Question 30: How must heating cable sets and heating panels be marked?

With the circuit number only
With the installation date only
With the maximum room size only
With identification and rated voltage and watts (or amperes)

NEC Reference: NEC 424.35

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.

Equipment for General Use (NEC 400/402/408/424/440/480) — NEC 2023 Edition

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Equipment for General Use (NEC 400/402/408/424/440/480) — NEC 2023 Edition

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Equipment for General Use (NEC 400/402/408/424/440/480) — NEC 2023 Edition — Question List

Question 1: What is the smallest fixture wire size permitted by the NEC?

Question 2: Where must the disconnecting means for air-conditioning or refrigerating equipment be located?

Question 3: Two cord-and-plug-connected room air conditioners are the only loads on a 30-ampere branch circuit. What is the maximum total marked rating of the two units?

Question 4: A transformer vault is protected by an automatic sprinkler system. What minimum fire rating is permitted for the vault doorway?

Question 5: Ground-fault protection of equipment is provided for an impedance heating system. What is the maximum transformer secondary voltage permitted?

Question 6: How must fixed outdoor electric deicing and snow-melting equipment be treated when sizing its branch circuit?

Question 7: Which of the following is an allowable ampacity of an 10 AWG fixture wire?

Question 8: According to the Article 100 definition of nominal voltage, what is the nominal voltage of a lead-acid cell?

Question 9: A disconnecting means for a motor circuit rated 1000 volts or less must have an ampere rating of at least what?

Question 10: A branch circuit supplies two or more outlets for fixed electric space-heating equipment. Which rating is NOT permitted for that circuit?

Question 11: A flexible cord generally cannot be used as a substitute for what?

Question 12: What does 408.36(C) say about delta breakers?

Question 13: A single cord-and-plug window air conditioner is supplied by a 15-ampere branch circuit. What is the maximum full-load current rating permitted for that unit?

Question 14: If a transformer vault doorway is NOT protected by an automatic sprinkler or water spray system, what fire rating does it generally require, versus the 1-hour rating used when sprinklers ARE present?

Question 15: An impedance heating system is NOT protected by ground-fault protection of equipment. What is the maximum transformer secondary voltage permitted?

Question 16: What is the general definition of a "continuous load" under the NEC?

Question 17: What is the allowable ampacity of a 14 AWG fixture wire according to Table 402.5?

Question 18: According to the Article 100 definition of nominal voltage, what is the nominal voltage of an alkali (nickel-cadmium) cell?

Question 19: A 300-volt motor has a full-load current of 40 amperes. What is the minimum ampere rating generally required for its disconnecting means?

Question 20: Branch circuits supplying two or more outlets for fixed electric space-heating equipment must be rated at which values?

Question 21: According to the informational note to the Article 100 definition of nominal voltage, what is the nominal voltage of a lithium-ion cell?

Question 22: What does the term "dusttight" mean in the NEC?

Question 23: A cord-and-plug-connected room air conditioner is on a 20-ampere branch circuit that also supplies lighting outlets. What is the maximum rating of the air conditioner?

Question 24: Because fixed outdoor deicing and snow-melting equipment is treated as a continuous load, its branch-circuit conductors and overcurrent protection are generally sized at not less than what percentage of the load current?

Question 25: Table 402.5 lists the allowable ampacity of fixture wires based on what?

Question 26: Panelboards must be of what type of construction?

Question 27: What protection must be provided for the branch circuit supplying fixed outdoor electric deicing and snow-melting equipment?

Question 28: Storage battery installations that can produce hydrogen gas generally require what, per NEC Article 480?

Question 29: How must the personnel doors of a transformer vault open, and what hardware do they need?

Question 30: How must heating cable sets and heating panels be marked?

Key NEC References for This Test

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