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NEC CODE NEC 2023

Over current Protection Practice Test Questions-2

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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 Over current Protection Practice Test Questions-2 has 10 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: 10 multiple-choice, one correct answer each

10

Questions

15 min

Time

70%

Pass

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Over current Protection Practice Test Questions-2 — Question List

Question 1: To protect a 12 AWG conductor what must the electrical fuse size?

20 amperes
15 amperes
25 amperes
30 amperes

NEC Reference: NEC 240.4(B)

Question 2: On a residential electric service which of the following conductors need over current protection?

un-grounded conductors
Grounded conductors
Neutral Conductor
Equipment Grounding Conductor

NEC Reference: NEC 240.25

Question 3: Three single phase motors with full load current rating of 20,30,25 amperes respectively are connected to 240 volts electrical circuit. Which of the following is the required dual element fuse size can be used for the circuit?

110 amperes
150 amperes
200 amperes
175 amperes

NEC Reference: NEC 430.52

Question 4: When a fuse or circuit breaker is used as over current protection device, they shall be connected .......................

in series
in parallel
both series and parallel
in tandem

Question 5: In an electrical system at what point branch circuit over current protection device should be located?

At the equipment ground location
At the end of branch circuit
At the panel board where they receive power supply
At the power outlet where power is consumed

NEC Reference: NEC 240.21

Question 6: A multi wire branch circuit may supply only .............. if it is protected by fuses.

line to line loads
line to neutral loads
receptacle loads
service loads

NEC Reference: NEC 210.4(C)

Question 7: A resistance welder connected to electrical system should maximum over current device rating ................. of the rated primary current of the welder?

Not over 100%
Not over 200%
Not over 300%
Not over 400%

Question 8: What is the maximum over current device rating required for an auto transformer that has a full load current of 50 amperes?

75 amperes
50 amperes
80 amperes
65 amperes

NEC Reference: NEC 450.4(A)

Question 9: The allowable ampere rating of bus conductor is 48 amperes. What is the maximum allowable rating of over current device?

50 amperes
40 amperes
60 amperes
70 amperes

NEC Reference: NEC 240.4(B)

Question 10: What is the smallest rating plug fuse that is used for residential 120 volts branch circuit?

15 amperes
20 amperes
12 amperes
18 amperes

NEC Reference: NEC 240.6(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.

EXAM CARD NEC CODE

Questions10

Time limit15 min

Pass score70%

Code editionNEC 2023

DifficultyIntermediate

Last reviewedJun 2026

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Source: NEC 2026 (NFPA 70)