AL EL-S Electrical Specialty Contractor
Exam Questions and Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf
1. Which measurement unit is used to express electrical resistance?
a. Volt
b. Ampere
c. Ohm
d. Watt
Rationale: Electrical resistance is measured in ohms (Ω). Resistance
represents the opposition a material or component presents to the flow
of electric current.
2. According to Ohm’s law, current is calculated by dividing voltage
by:
a. Power
b. Resistance
,c. Frequency
d. Capacitance
Rationale: Ohm’s law is I = E/R, where I is current in amperes, E is
voltage in volts, and R is resistance in ohms.
3. A 120-volt circuit has a resistance of 20 ohms. What current flows
through the circuit?
a. 2 A
b. 4 A
c. 6 A
d. 10 A
Rationale: Using Ohm’s law, I = E/R = 120/20 = 6 amperes.
4. What is the primary purpose of an overcurrent protective device?
a. Increase circuit voltage
b. Improve power factor
c. Protect conductors and equipment from excessive current
d. Increase conductor resistance
Rationale: Fuses and circuit breakers are designed to interrupt excessive
current before conductors or connected equipment are damaged by
overheating.
, 5. Which device is designed to open a circuit automatically when
excessive current occurs?
a. Transformer
b. Receptacle
c. Circuit breaker
d. Junction box
Rationale: A circuit breaker senses an overcurrent condition and opens
the circuit. It can generally be reset after the fault has been corrected.
6. What is the purpose of a grounding electrode system?
a. To increase normal operating voltage
b. To provide a path for normal load current
c. To connect the electrical system to earth for grounding purposes
d. To eliminate the need for overcurrent protection
Rationale: The grounding electrode system connects the electrical
system to earth and helps stabilize voltage to ground and dissipate
certain electrical disturbances.
7. Which conductor normally carries current back to the source in a
typical single-phase circuit?
a. Equipment grounding conductor
b. Grounding electrode conductor
, c. Grounded conductor
d. Bonding jumper
Rationale: The grounded conductor, commonly called the neutral in
many systems, normally carries return current from the load back to the
source.
8. What color is commonly used to identify an equipment grounding
conductor?
a. White
b. Gray
c. Green or bare
d. Orange
Rationale: Equipment grounding conductors are commonly identified by
green insulation, green with yellow stripe, or by being bare, depending
on the wiring method.
9. What is the primary purpose of bonding?
a. To increase resistance
b. To create a higher operating voltage
c. To establish an effective path for fault current
d. To reduce conductor ampacity
Exam Questions and Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf
1. Which measurement unit is used to express electrical resistance?
a. Volt
b. Ampere
c. Ohm
d. Watt
Rationale: Electrical resistance is measured in ohms (Ω). Resistance
represents the opposition a material or component presents to the flow
of electric current.
2. According to Ohm’s law, current is calculated by dividing voltage
by:
a. Power
b. Resistance
,c. Frequency
d. Capacitance
Rationale: Ohm’s law is I = E/R, where I is current in amperes, E is
voltage in volts, and R is resistance in ohms.
3. A 120-volt circuit has a resistance of 20 ohms. What current flows
through the circuit?
a. 2 A
b. 4 A
c. 6 A
d. 10 A
Rationale: Using Ohm’s law, I = E/R = 120/20 = 6 amperes.
4. What is the primary purpose of an overcurrent protective device?
a. Increase circuit voltage
b. Improve power factor
c. Protect conductors and equipment from excessive current
d. Increase conductor resistance
Rationale: Fuses and circuit breakers are designed to interrupt excessive
current before conductors or connected equipment are damaged by
overheating.
, 5. Which device is designed to open a circuit automatically when
excessive current occurs?
a. Transformer
b. Receptacle
c. Circuit breaker
d. Junction box
Rationale: A circuit breaker senses an overcurrent condition and opens
the circuit. It can generally be reset after the fault has been corrected.
6. What is the purpose of a grounding electrode system?
a. To increase normal operating voltage
b. To provide a path for normal load current
c. To connect the electrical system to earth for grounding purposes
d. To eliminate the need for overcurrent protection
Rationale: The grounding electrode system connects the electrical
system to earth and helps stabilize voltage to ground and dissipate
certain electrical disturbances.
7. Which conductor normally carries current back to the source in a
typical single-phase circuit?
a. Equipment grounding conductor
b. Grounding electrode conductor
, c. Grounded conductor
d. Bonding jumper
Rationale: The grounded conductor, commonly called the neutral in
many systems, normally carries return current from the load back to the
source.
8. What color is commonly used to identify an equipment grounding
conductor?
a. White
b. Gray
c. Green or bare
d. Orange
Rationale: Equipment grounding conductors are commonly identified by
green insulation, green with yellow stripe, or by being bare, depending
on the wiring method.
9. What is the primary purpose of bonding?
a. To increase resistance
b. To create a higher operating voltage
c. To establish an effective path for fault current
d. To reduce conductor ampacity
