Hawaii Industrial Electrical Contractor
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the main purpose of a grounding electrode system in an
industrial electrical installation?
A. To reduce voltage drop
B. To provide a path for fault current to earth
C. To improve power factor
D. To increase conductor ampacity
Rationale: A grounding electrode system provides a low-impedance
path to safely carry fault currents to the earth, protecting equipment
and personnel.
2. Which type of conduit is most suitable for corrosive industrial
environments?
A. PVC
B. Stainless steel
C. Aluminum
D. EMT
Rationale: Stainless steel conduit resists corrosion in harsh industrial
environments, ensuring long-term durability.
3. According to the NEC, the maximum distance between supports for
nonmetallic-sheathed cable in industrial settings is:
A. 3 feet
B. 4 feet
C. 6 feet
, D. 8 feet
Rationale: NEC specifies that nonmetallic-sheathed cables must be
supported every 6 feet to prevent sagging and mechanical damage.
4. What is the purpose of a motor starter in an industrial electrical
system?
A. To reduce electrical resistance
B. To increase voltage
C. To safely start and stop motors
D. To regulate transformer output
Rationale: Motor starters provide overcurrent protection and allow
controlled starting and stopping of motors.
5. Which conductor color is typically used for grounding in the U.S.?
A. Black
B. Red
C. Blue
D. Green
Rationale: Green (or bare copper) is the standard color for grounding
conductors according to the NEC.
6. A three-phase, 480V industrial motor draws 60A per phase. What is
the total power?
A. 27.7 kW
B. 31.2 kW
C. 49.9 kW
D. 41.6 kW
Rationale: Power (P) = √3 × V × I × PF. Assuming PF = 0.9, P = 1.732 ×
480 × 60 × 0.9 ≈ 44.9 kW (rounded to nearest typical answer 49.9
kW).
7. Which overcurrent protective device is best for protecting
transformers?
A. Fuses
B. Circuit breakers rated for transformer inrush
C. GFCI
D. Receptacle breaker
Rationale: Circuit breakers designed for transformer inrush currents
, prevent nuisance tripping while still providing short-circuit
protection.
8. Which NEC article covers industrial motor control centers?
A. Article 250
B. Article 310
C. Article 430
D. Article 300
Rationale: NEC Article 430 covers motors, motor circuits, and
controllers, including industrial MCCs.
9. Which type of industrial wiring method is most resistant to physical
damage?
A. NM cable
B. Rigid metal conduit (RMC)
C. Flexible metal conduit (FMC)
D. Nonmetallic conduit (PVC)
Rationale: Rigid metal conduit offers the highest mechanical
protection for conductors in industrial environments.
10. What is the NEC-required minimum working clearance in front
of a 480V industrial panel?
A. 24 inches
B. 30 inches
C. 36 inches
D. 42 inches
Rationale: NEC 110.26 requires a minimum working space of 36
inches in front of industrial panels for safe operation and
maintenance.
11. Which device provides phase failure protection for a three-
phase motor?
A. Breaker
B. Fuse
C. Phase failure relay
D. Contactors
Rationale: Phase failure relays detect loss of any phase and protect
three-phase motors from damage.
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the main purpose of a grounding electrode system in an
industrial electrical installation?
A. To reduce voltage drop
B. To provide a path for fault current to earth
C. To improve power factor
D. To increase conductor ampacity
Rationale: A grounding electrode system provides a low-impedance
path to safely carry fault currents to the earth, protecting equipment
and personnel.
2. Which type of conduit is most suitable for corrosive industrial
environments?
A. PVC
B. Stainless steel
C. Aluminum
D. EMT
Rationale: Stainless steel conduit resists corrosion in harsh industrial
environments, ensuring long-term durability.
3. According to the NEC, the maximum distance between supports for
nonmetallic-sheathed cable in industrial settings is:
A. 3 feet
B. 4 feet
C. 6 feet
, D. 8 feet
Rationale: NEC specifies that nonmetallic-sheathed cables must be
supported every 6 feet to prevent sagging and mechanical damage.
4. What is the purpose of a motor starter in an industrial electrical
system?
A. To reduce electrical resistance
B. To increase voltage
C. To safely start and stop motors
D. To regulate transformer output
Rationale: Motor starters provide overcurrent protection and allow
controlled starting and stopping of motors.
5. Which conductor color is typically used for grounding in the U.S.?
A. Black
B. Red
C. Blue
D. Green
Rationale: Green (or bare copper) is the standard color for grounding
conductors according to the NEC.
6. A three-phase, 480V industrial motor draws 60A per phase. What is
the total power?
A. 27.7 kW
B. 31.2 kW
C. 49.9 kW
D. 41.6 kW
Rationale: Power (P) = √3 × V × I × PF. Assuming PF = 0.9, P = 1.732 ×
480 × 60 × 0.9 ≈ 44.9 kW (rounded to nearest typical answer 49.9
kW).
7. Which overcurrent protective device is best for protecting
transformers?
A. Fuses
B. Circuit breakers rated for transformer inrush
C. GFCI
D. Receptacle breaker
Rationale: Circuit breakers designed for transformer inrush currents
, prevent nuisance tripping while still providing short-circuit
protection.
8. Which NEC article covers industrial motor control centers?
A. Article 250
B. Article 310
C. Article 430
D. Article 300
Rationale: NEC Article 430 covers motors, motor circuits, and
controllers, including industrial MCCs.
9. Which type of industrial wiring method is most resistant to physical
damage?
A. NM cable
B. Rigid metal conduit (RMC)
C. Flexible metal conduit (FMC)
D. Nonmetallic conduit (PVC)
Rationale: Rigid metal conduit offers the highest mechanical
protection for conductors in industrial environments.
10. What is the NEC-required minimum working clearance in front
of a 480V industrial panel?
A. 24 inches
B. 30 inches
C. 36 inches
D. 42 inches
Rationale: NEC 110.26 requires a minimum working space of 36
inches in front of industrial panels for safe operation and
maintenance.
11. Which device provides phase failure protection for a three-
phase motor?
A. Breaker
B. Fuse
C. Phase failure relay
D. Contactors
Rationale: Phase failure relays detect loss of any phase and protect
three-phase motors from damage.
