Questions and Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. What is the primary purpose of the National Electrical Code
(NEC)?
A. To reduce construction costs
B. To establish minimum standards for electrical safety
C. To eliminate all electrical hazards
D. To replace local building codes
Answer: B. To establish minimum standards for electrical safety
Rationale: The NEC is designed to provide practical safeguarding of
persons and property from hazards arising from the use of electricity.
It establishes minimum safety requirements, not design specifications
or guarantees of hazard elimination.
2. Which type of current changes direction periodically?
,A. Direct Current (DC)
B. Static Current
C. Alternating Current (AC)
D. Pulsed Current
Rationale: Alternating current (AC) reverses direction at regular
intervals, typically 60 times per second (60 Hz) in the United States.
Most residential and commercial electrical systems use AC power.
3. According to the NEC, electrical equipment must be installed:
A. According to customer preference
B. According to manufacturer advertising
C. In accordance with its listing and labeling instructions
D. Only according to local practice
Rationale: NEC requires listed and labeled equipment to be installed
and used according to any instructions included in the listing or
labeling. Ignoring manufacturer instructions can create unsafe
conditions.
4. Which instrument measures electrical resistance?
,A. Ammeter
B. Voltmeter
C. Ohmmeter
D. Wattmeter
Rationale: An ohmmeter measures resistance in ohms. Resistance
measurements should be made only on de-energized circuits to
prevent damage to the meter and ensure safety.
5. What does Ohm's Law state?
A. Power equals voltage times current
B. Voltage equals current multiplied by resistance
C. Current equals power divided by voltage
D. Resistance equals power multiplied by voltage
Rationale: Ohm's Law is expressed as V = I × R. It is the fundamental
relationship between voltage, current, and resistance and is essential
for electrical calculations.
6. What is the unit of electrical power?
A. Volt
B. Ampere
, C. Ohm
D. Watt
Rationale: Electrical power is measured in watts. Power is calculated
by multiplying voltage by current (P = V × I).
7. Conductors are primarily sized according to:
A. Their color
B. The amount of current they are expected to carry
C. The age of the building
D. The type of switch used
Rationale: Conductors must be sized based on ampacity, considering
insulation type, temperature rating, installation conditions, and
continuous loading requirements.
8. Copper conductors generally have:
A. Higher resistance than aluminum
B. Lower resistance than aluminum
C. Equal resistance to aluminum
D. No measurable resistance