Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
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1. What is the primary purpose of the National Electrical Code (NEC)?
A. To design electrical systems
B. To establish safety standards for electrical installations
C. To regulate electrical pricing
D. To certify electricians
Answer: B
Rationale: The NEC provides minimum safety standards to protect
people and property from electrical hazards.
2. The maximum voltage drop recommended by NEC for branch circuits
is:
A. 1%
B. 3%
C. 5%
D. 10%
Answer: C
Rationale: NEC recommends no more than 3% on branch circuits and
5% total feeder plus branch.
3. Which device protects against overloads and short circuits?
A. Transformer
B. Circuit breaker
C. Switch
D. Receptacle
Answer: B
, Rationale: Circuit breakers automatically interrupt current during
overload or short circuit conditions.
4. The unit of electrical resistance is:
A. Volt
B. Ampere
C. Ohm
D. Watt
Answer: C
Rationale: Resistance is measured in ohms (Ω).
5. Ohm’s Law is expressed as:
A. P = IV
B. V = IR
C. I = PR
D. R = VI
Answer: B
Rationale: Ohm’s Law states voltage equals current times resistance
(V = IR).
6. A grounded conductor is typically:
A. Green
B. White or gray
C. Black
D. Red
Answer: B
Rationale: Neutral (grounded) conductors are identified by white or
gray insulation.
7. The purpose of grounding is to:
A. Increase voltage
B. Stabilize system voltage and provide fault path
C. Reduce resistance
D. Increase current
Answer: B
Rationale: Grounding provides a safe path for fault current and
stabilizes voltage.
8. The standard frequency of AC power in the U.S. is:
A. 50 Hz
, B. 60 Hz
C. 120 Hz
D. 100 Hz
Answer: B
Rationale: U.S. electrical systems operate at 60 Hz.
9. A GFCI device is designed to protect against:
A. Overvoltage
B. Ground faults
C. Overcurrent
D. Power surges
Answer: B
Rationale: GFCIs detect leakage current and protect against ground
faults.
10. The color of equipment grounding conductor is:
A. White
B. Black
C. Green or bare
D. Blue
Answer: C
Rationale: Equipment grounding conductors are green or bare
copper.
11. Conduit fill is governed primarily by:
A. OSHA
B. NEC Chapter 9
C. IEEE
D. NFPA 70E
Answer: B
Rationale: NEC Chapter 9 provides tables for conduit fill
requirements.
12. A series circuit has:
A. Multiple current paths
B. One current path
C. No resistance
D. Variable voltage only