Previous Synchronous Generator Practice Questions Next commercial load calculations-2

BASIC NEC 2023

circuit breaker theory quiz question and answers

Free online quiz practice test on circuit breaker

TOPICS COVERED

Electrical Practice Questions

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 21 min for 10 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.

How to Use This Practice Test

This circuit breaker theory quiz question and answers has 14 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: Work through Ohm's Law problems on paper — don't just read the answers, calculate them yourself.

Topics covered: Voltage, current, resistance, Ohm's Law, series/parallel circuits, and electrical safety.
Passing score: Aim for 90%+ on basic theory — these fundamentals underpin every advanced topic.
Questions: 14 multiple-choice, one correct answer each

10

Questions

21 min

Time

70%

Pass

Timer starts immediately. Progress is auto-saved.

circuit breaker theory quiz question and answers — Question List

Question 1: The circuit breaker is placed in a power system …………………………..

To interrupt the current flow system
To interrupt the voltage flow in system
To reduce the reactive power in system
To interrupt the active power flow in system

Question 2: If the arc in the circuit breaker is absent during the opening of circuit contacts ……………………….

A high switch over voltage will flow in the circuit
A high current will flow in the circuit
High temperature in the circuit breaker cabinet damages the breaker enclosure
High reactive power flows in the circuit

Question 3: Which of the SF6 property specifies that it has high arc quenching medium?

Electronegativity
Electropositivity
High thermal conductivity
High density

Question 4: Which of the following circuit breaker should not be used in high voltage power systems?

Minimum oil circuit breaker
air blast circuit breaker
SF6 circuit breaker
Oil circuit breaker

Question 5: The voltage that presents at breaking contact at the instant of arc extinction is called as ……………….

Restricting voltage
Recovery voltage
Arc voltage
Active recovery voltage

Question 6: The major function of the relay in circuit breaker is…………………………

To interrupt the current flow
To activate the trip signal to open the contacts
To protect the circuit break from high short circuit currents
To help in faster switching

Question 7: The air circuit breaker can be used up to the voltage level of ………………. KV

15
21
6.6
11

Question 8: Low resistance method of arc interruption is applicable for only …………………

AC circuits
DC circuits
AC circuits with low voltage
DC circuits with low voltage

Question 9: Which of the following circuit breakers are used for extra high voltage power systems?

Oil circuit breakers
Air circuit breakers
SF6 circuit breakers
Bulk oil circuit breakers

Question 10: What does GIS stands for?

Gas insulated switchgear
Gas insulated system
Gas interrupted switch gear
Gas interrupted system

EXAM CARD BASIC

Questions10

Time limit21 min

Pass score70%

Code editionNEC 2023

DifficultyIntermediate

Last reviewedJun 2026

Timer starts immediately. Progress is auto-saved.

Source: NEC 2026 (NFPA 70)