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Flexible Cords and Fixture Wires (NEC 400/402) — NEC 2023 Edition

Free NEC 2023 practice test on flexible cords and fixture wires. Covers permitted and prohibited uses of flexible cords, ampacity adjustment for grouped conductors, overcurrent protection, and fixture wire sizing. 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).

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This Flexible Cords and Fixture Wires (NEC 400/402) — 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.
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Questions: 30 multiple-choice, one correct answer each

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Flexible Cords and Fixture Wires (NEC 400/402) — NEC 2023 Edition — Question List

Question 1: True or false: flexible cord or cable generally cannot be used as a substitute for the fixed (permanent) wiring of a structure.

True
False
Only in commercial buildings
Only for cords over 50 feet

NEC Reference: NEC 400.12

Question 2: Eight 16-ampere current-carrying conductors are grouped together in a flexible cord. What is the allowable ampacity of each conductor after adjustment?

11.2 amperes
16 amperes
12.8 amperes
14.4 amperes

NEC Reference: NEC Table 400.5(A)(3)

Question 3: In which of the following situations is a flexible cord generally NOT permitted to be used?

Wiring of cranes and hoists
Connection of moving parts
Elevator cables
Attached to building surfaces

NEC Reference: NEC 400.12

Question 4: The overcurrent device protecting a flexible cord or cable must not be rated how, relative to the cord's ampacity?

Higher than the cord's ampacity
Lower than the cord's ampacity
125% lower than the cord's ampacity
125% higher than the cord's ampacity

NEC Reference: NEC 400.13 / 240.5

Question 5: What is the minimum size fixture wire generally permitted for wiring control circuits?

18 AWG
16 AWG
10 AWG
12 AWG

NEC Reference: NEC 402.6

Question 6: What is the allowable ampacity of a 10 AWG fixture wire?

NEC Reference: NEC Table 402.5

Question 7: Unless specifically permitted, fixture wires cannot generally be used for which type of wiring?

Branch circuit wiring
Elevator and escalator control circuits
To connect luminaires
Fire alarm circuits

NEC Reference: NEC 402.10

Question 8: When 5 current-carrying conductors are grouped together in a flexible cord, what percent of the rated ampacity is allowed for each conductor?

NEC Reference: NEC Table 400.5(A)(3)

Question 9: Which of the following IS a permitted use of flexible cord, per NEC 400.10?

Pendant luminaires
Fixed permanent wiring in walls
Underground burial
Concealed within concrete

NEC Reference: NEC 400.10(A)

Question 10: Flexible cords must generally be marked, at intervals, with what information?

Type, size, and number of conductors
Nothing is required
Only the manufacturer's logo
Only the purchase date

NEC Reference: NEC 400.6

Question 11: True or false: flexible cords generally must not contain splices or taps.

True
False
Only for indoor cords
Only for cords under 6 feet

NEC Reference: NEC 400.9

Question 12: Flexible cords must generally be protected from what, wherever passing through a wall, floor, or other surface?

Physical damage from sharp edges
Nothing -- no protection is needed
Only sunlight
Only rodents

NEC Reference: NEC 400.14

Question 13: Per NEC Table 400.5(A)(3), what adjustment factor applies for 2-3 current-carrying conductors bundled together?

It depends on the exact conductor count per the table
Always exactly 50%, no matter what
Always exactly 25%, no matter what
There is never any adjustment

NEC Reference: NEC Table 400.5(A)(3)

Question 14: Fixture wires are generally selected based on their insulation type and what other key characteristic, listed in NEC Table 402.3?

Maximum operating temperature rating
The manufacturer's logo
The wire's color only
Nothing else matters

NEC Reference: NEC Table 402.3

Question 15: In a flexible cord, the grounded (neutral) conductor is generally identified by what color or marking?

White, gray, or another approved marking
Always bright orange
No marking is ever used
Always black

NEC Reference: NEC 400.22

Question 16: Extension cords used on a construction site are generally covered under which special NEC article, in addition to Article 400?

Article 590 (temporary wiring)
Article 250 only
Article 90 only
No article covers this

NEC Reference: NEC Article 590

Question 17: Fixture wires generally range in size from 18 AWG up to what maximum size, per NEC Article 402?

10 AWG
6 AWG
2 AWG
1/0 AWG

NEC Reference: NEC Article 402

Question 18: Flexible cords are classified by service conditions such as "hard usage" and "extra-hard usage." What does this classification generally indicate?

The cord's durability for different physical conditions
The cord's color only
Nothing meaningful
Only the price category

NEC Reference: NEC Table 400.4

Question 19: The ampacity of flexible cords and cables, per NEC Table 400.5(A)(1) and (A)(2), depends on the conductor size and what other factor?

The number of current-carrying conductors
The cord's brand name
The room temperature only
Nothing else matters

NEC Reference: NEC Table 400.5(A)(1)

Question 20: Can fixture wire generally be used as service-entrance conductors for a building?

No, it is not suitable for that use
Yes, always freely permitted
Only for very small services
Only in dwelling units

NEC Reference: NEC Article 402 / 230.41

Question 21: Is flexible cord permitted for connecting portable lamps and appliances?

Yes
No, never
Only outdoors
Only in industrial buildings

NEC Reference: NEC 400.10(A)

Question 22: Is a flexible cord generally permitted to run through a doorway, window, or similar opening as a permanent installation?

No, this is generally prohibited
Yes, always permitted
Only for cords under 3 feet
Only in garages

NEC Reference: NEC 400.12

Question 23: What is the allowable ampacity of a 12 AWG fixture wire, per NEC Table 402.5?

25 amperes
20 amperes
30 amperes
15 amperes

NEC Reference: NEC Table 402.5

Question 24: True or false: flexible cord is generally not permitted to be run through holes in walls, structural ceilings, or floors, as a fixed installation.

True
False
Only for cords rated over 300V
Only outdoors

NEC Reference: NEC 400.12

Question 25: What is generally the smallest conductor size permitted for a general-purpose flexible cord, per NEC Table 400.4?

18 AWG
14 AWG
12 AWG
10 AWG

NEC Reference: NEC Table 400.4

Question 26: A flexible cord supplying a grounding-type appliance must generally include what additional conductor?

An equipment grounding conductor
A telephone wire
Nothing extra is needed
A second neutral only

NEC Reference: NEC 400.23

Question 27: An attachment plug on a flexible cord must generally maintain proper what, matching the conductor identification within the cord?

Polarity
Color only, with no electrical significance
Nothing -- wiring order does not matter
Weight balance only

NEC Reference: NEC 400.23 / general wiring rules

Question 28: True or false: flexible cords are generally permitted to be concealed behind building walls, ceilings, or floors as a permanent wiring method.

True
False
Only for cords under 25 feet
Only in commercial buildings

NEC Reference: NEC 400.12

Question 29: NEC Table 402.3 lists various fixture wire types by their insulation and temperature rating. Why does this matter for luminaire installations?

It must withstand the heat inside the fixture
It has no practical significance
Only the wire color matters
Temperature rating is irrelevant to fixture wire

NEC Reference: NEC Table 402.3

Question 30: Is flexible cord a permitted method for connecting portable power tools to a branch circuit?

Yes
No, never permitted
Only outdoors
Only for tools under 1 amp

NEC Reference: NEC 400.10(A)

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.

Flexible Cords and Fixture Wires (NEC 400/402) — NEC 2023 Edition

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Key NEC References for This Test

Flexible Cords and Fixture Wires (NEC 400/402) — NEC 2023 Edition

How this test works

Frequently Asked Questions

Is this Flexible Cords and Fixture Wires (NEC 400/402) — 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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Flexible Cords and Fixture Wires (NEC 400/402) — NEC 2023 Edition — Question List

Question 1: True or false: flexible cord or cable generally cannot be used as a substitute for the fixed (permanent) wiring of a structure.

Question 2: Eight 16-ampere current-carrying conductors are grouped together in a flexible cord. What is the allowable ampacity of each conductor after adjustment?

Question 3: In which of the following situations is a flexible cord generally NOT permitted to be used?

Question 4: The overcurrent device protecting a flexible cord or cable must not be rated how, relative to the cord's ampacity?

Question 5: What is the minimum size fixture wire generally permitted for wiring control circuits?

Question 6: What is the allowable ampacity of a 10 AWG fixture wire?

Question 7: Unless specifically permitted, fixture wires cannot generally be used for which type of wiring?

Question 8: When 5 current-carrying conductors are grouped together in a flexible cord, what percent of the rated ampacity is allowed for each conductor?

Question 9: Which of the following IS a permitted use of flexible cord, per NEC 400.10?

Question 10: Flexible cords must generally be marked, at intervals, with what information?

Question 11: True or false: flexible cords generally must not contain splices or taps.

Question 12: Flexible cords must generally be protected from what, wherever passing through a wall, floor, or other surface?

Question 13: Per NEC Table 400.5(A)(3), what adjustment factor applies for 2-3 current-carrying conductors bundled together?

Question 14: Fixture wires are generally selected based on their insulation type and what other key characteristic, listed in NEC Table 402.3?

Question 15: In a flexible cord, the grounded (neutral) conductor is generally identified by what color or marking?

Question 16: Extension cords used on a construction site are generally covered under which special NEC article, in addition to Article 400?

Question 17: Fixture wires generally range in size from 18 AWG up to what maximum size, per NEC Article 402?

Question 18: Flexible cords are classified by service conditions such as "hard usage" and "extra-hard usage." What does this classification generally indicate?

Question 19: The ampacity of flexible cords and cables, per NEC Table 400.5(A)(1) and (A)(2), depends on the conductor size and what other factor?

Question 20: Can fixture wire generally be used as service-entrance conductors for a building?

Question 21: Is flexible cord permitted for connecting portable lamps and appliances?

Question 22: Is a flexible cord generally permitted to run through a doorway, window, or similar opening as a permanent installation?

Question 23: What is the allowable ampacity of a 12 AWG fixture wire, per NEC Table 402.5?

Question 24: True or false: flexible cord is generally not permitted to be run through holes in walls, structural ceilings, or floors, as a fixed installation.

Question 25: What is generally the smallest conductor size permitted for a general-purpose flexible cord, per NEC Table 400.4?

Question 26: A flexible cord supplying a grounding-type appliance must generally include what additional conductor?

Question 27: An attachment plug on a flexible cord must generally maintain proper what, matching the conductor identification within the cord?

Question 28: True or false: flexible cords are generally permitted to be concealed behind building walls, ceilings, or floors as a permanent wiring method.

Question 29: NEC Table 402.3 lists various fixture wire types by their insulation and temperature rating. Why does this matter for luminaire installations?

Question 30: Is flexible cord a permitted method for connecting portable power tools to a branch circuit?

Key NEC References for This Test

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