AL EL-S Electrical Specialty
Contractor Exam Questions And
Correct Answers (Verified Answers)
Plus Rationale2026 Q&A| Instant
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1. What is the primary function of a circuit breaker?
A) Store electricity
B) Interrupt excess current
C) Increase voltage
D) Convert AC to DC
Rationale:
Circuit breakers protect electrical circuits by interrupting excess current to
prevent damage and fire hazards.
2. Which conductor color is typically used for grounding in residential
wiring?
A) Red
B) Blue
C) Green or bare copper
D) White
Rationale:
Green or bare copper conductors are standard for grounding to ensure
safety.
3. What is the unit of electrical resistance?
A) Volt
, B) Ampere
C) Watt
D) Ohm
Rationale:
Resistance is measured in ohms, indicating how much a material opposes
the flow of current.
4. Which type of wiring is most commonly used in commercial buildings?
A) NM cable
B) Conduit (EMT, PVC, or rigid)
C) Knob and tube
D) Aluminum tape wiring
Rationale:
Conduit protects wires and meets commercial code requirements, unlike
NM cable primarily used in residential wiring.
5. What is the purpose of a GFCI (Ground Fault Circuit Interrupter)?
A) Increase current flow
B) Protect people from electric shock
C) Reduce voltage
D) Measure energy consumption
Rationale:
GFCIs detect ground faults and quickly shut off power to prevent
electrocution.
6. Which device converts alternating current (AC) to direct current (DC)?
A) Transformer
B) Capacitor
C) Rectifier
D) Circuit breaker
Rationale:
A rectifier converts AC to DC for devices that require direct current.
7. In three-phase wiring, what is the typical phase-to-phase voltage in the
U.S.?
, A) 120V
B) 208V
C) 480V
D) 600V
Rationale:
Standard commercial three-phase systems often use 480V phase-to-phase.
8. What does NEC stand for?
A) National Energy Code
B) National Electrical Code
C) National Engineering Code
D) National Equipment Code
Rationale:
The NEC sets safety standards for electrical design, installation, and
inspection.
9. Which type of fire extinguisher is appropriate for electrical fires?
A) Water
B) Foam
C) CO2 or dry chemical
D) Wet chemical
Rationale:
CO2 and dry chemical extinguishers are non-conductive and safe for
electrical fires.
10. What is the primary purpose of a transformer?
A) Store energy
B) Convert DC to AC
C) Change voltage levels
D) Measure current
Rationale:
Transformers increase or decrease AC voltage to suit equipment
requirements.
Contractor Exam Questions And
Correct Answers (Verified Answers)
Plus Rationale2026 Q&A| Instant
Download Pdf
1. What is the primary function of a circuit breaker?
A) Store electricity
B) Interrupt excess current
C) Increase voltage
D) Convert AC to DC
Rationale:
Circuit breakers protect electrical circuits by interrupting excess current to
prevent damage and fire hazards.
2. Which conductor color is typically used for grounding in residential
wiring?
A) Red
B) Blue
C) Green or bare copper
D) White
Rationale:
Green or bare copper conductors are standard for grounding to ensure
safety.
3. What is the unit of electrical resistance?
A) Volt
, B) Ampere
C) Watt
D) Ohm
Rationale:
Resistance is measured in ohms, indicating how much a material opposes
the flow of current.
4. Which type of wiring is most commonly used in commercial buildings?
A) NM cable
B) Conduit (EMT, PVC, or rigid)
C) Knob and tube
D) Aluminum tape wiring
Rationale:
Conduit protects wires and meets commercial code requirements, unlike
NM cable primarily used in residential wiring.
5. What is the purpose of a GFCI (Ground Fault Circuit Interrupter)?
A) Increase current flow
B) Protect people from electric shock
C) Reduce voltage
D) Measure energy consumption
Rationale:
GFCIs detect ground faults and quickly shut off power to prevent
electrocution.
6. Which device converts alternating current (AC) to direct current (DC)?
A) Transformer
B) Capacitor
C) Rectifier
D) Circuit breaker
Rationale:
A rectifier converts AC to DC for devices that require direct current.
7. In three-phase wiring, what is the typical phase-to-phase voltage in the
U.S.?
, A) 120V
B) 208V
C) 480V
D) 600V
Rationale:
Standard commercial three-phase systems often use 480V phase-to-phase.
8. What does NEC stand for?
A) National Energy Code
B) National Electrical Code
C) National Engineering Code
D) National Equipment Code
Rationale:
The NEC sets safety standards for electrical design, installation, and
inspection.
9. Which type of fire extinguisher is appropriate for electrical fires?
A) Water
B) Foam
C) CO2 or dry chemical
D) Wet chemical
Rationale:
CO2 and dry chemical extinguishers are non-conductive and safe for
electrical fires.
10. What is the primary purpose of a transformer?
A) Store energy
B) Convert DC to AC
C) Change voltage levels
D) Measure current
Rationale:
Transformers increase or decrease AC voltage to suit equipment
requirements.
