Hawaii C 13 Electrical Contractor
Examination with Practice Questions And
Correct Answers
1. A commercial service in Honolulu is supplied by a 120/208V, 3-phase, 4-wire system.
The calculated load is 180A continuous and 60A noncontinuous. If the service
disconnect is rated for 100% continuous operation, what is the minimum standard
ampere rating required?
A. 200A
B. 225A
C. 250A
D. 300A
Answer: C. 250A
Rationale: For a 100%-rated disconnect, the continuous load is not multiplied by 125%, so
total = 180A + 60A = 240A. The next standard size above 240A is 250A per NEC 240.6. A
200A or 225A device would be undersized; 300A is larger than necessary.
2. A 3-phase, 480V delta primary to 208Y/120V secondary transformer supplies a 150
kVA balanced load. If the primary conductors are copper with 75°C insulation and the
ambient temperature is 40°C, what is the minimum ampacity adjustment factor
applied to the primary conductor ampacity?
A. 0.88
B. 0.91
C. 0.94
D. 1.00
Answer: A. 0.88
Rationale: NEC Table 310.15(B)(2)(a) for 75°C conductors in a 40°C ambient gives a
correction factor of 0.88. The primary current is 150,000 / (480 × 1.732) 180A, and the
adjusted ampacity must be based on the 0.88 factor. Options B, C, and D correspond to
lower ambient temperatures or no adjustment.
Page 1 of 71
,3. A dwelling unit has a 200A, 120/240V service. The calculated load is 180A. If the
utility requires a minimum 100A service and the meter socket is rated 200A, what is
the minimum size copper grounding electrode conductor to a ground rod?
A. 6 AWG
B. 4 AWG
C. 2 AWG
D. 1/0 AWG
Answer: A. 6 AWG
Rationale: NEC Table 250.66 requires a 6 AWG copper grounding electrode conductor for
a 200A service when the service-entrance conductors are 2/0 AWG or smaller. A 4 AWG or
larger is only required for larger service conductors. Ground rod connection is further
permitted to be 6 AWG per 250.66(A).
4. In a commercial kitchen, a 208V, 3-phase, 12 kW deep fryer is connected to a 30A
branch circuit. If the equipment nameplate specifies a minimum circuit ampacity of
35A and maximum overcurrent protection of 40A, which of the following is the correct
conductor and breaker selection?
A. 10 AWG copper, 30A breaker
B. 8 AWG copper, 40A breaker
C. 10 AWG copper, 40A breaker
D. 8 AWG copper, 30A breaker
Answer: B. 8 AWG copper, 40A breaker
Rationale: The nameplate minimum circuit ampacity of 35A requires a conductor rated at
least 35A; 8 AWG copper at 75°C is rated 50A, while 10 AWG is only 35A at 75°C but may
be insufficient for continuous load. The maximum overcurrent protection of 40A dictates a
40A breaker. Thus 8 AWG copper with a 40A breaker is correct.
Page 2 of 71
,5. A 1,200 sq ft single-family dwelling in Hawaii has a 240V, single-phase service. The
calculated general lighting load is 3 VA per sq ft, and there are two 20A
small-appliance branch circuits and one 20A laundry circuit. Using the optional
method, what is the minimum service size?
A. 100A
B. 125A
C. 150A
D. 200A
Answer: B. 125A
Rationale: Using NEC 220.82 optional method: general lighting = 3,600 VA, small
appliance = 3,000 VA, laundry = 1,500 VA. Total = 8,100 VA. First 10,000 VA at 100% =
8,100 VA; demand = 8,100 VA. At 240V, 8, = 33.75A, but the minimum service is
100A. However, with a 240V service and typical dwelling, 125A is the next standard size
after applying demand factors and considering future loads. The correct minimum is 125A.
6. A 480V, 3-phase motor has a nameplate FLA of 52A. The motor is on a 75°C rated
circuit. What is the minimum size THWN copper conductor and the maximum rating
of the short-circuit and ground-fault protective device?
A. 6 AWG, 70A breaker
B. 6 AWG, 100A breaker
C. 4 AWG, 100A breaker
D. 4 AWG, 70A breaker
Answer: C. 4 AWG, 100A breaker
Rationale: NEC Table 430.250 for a 480V, 3-phase motor with 52A FLA requires
conductors with ampacity 52A × 1.25 = 65A. 6 AWG at 75°C is 65A, but 4 AWG is 85A and
is safer for voltage drop. The maximum breaker is typically 250% of FLA = 130A, but
standard size is 100A. Thus 4 AWG and 100A is correct.
Page 3 of 71
, 7. In a hazardous (classified) location, Class I, Division 1, Group C, which of the
following wiring methods is permitted for a 120V lighting circuit?
A. Rigid metal conduit with threaded joints and seal-offs
B. Electrical metallic tubing with compression fittings
C. PVC Schedule 80 conduit with solvent-welded joints
D. Type MC cable with an overall jacket
Answer: A. Rigid metal conduit with threaded joints and seal-offs
Rationale: NEC 501.10(A)(1) permits rigid metal conduit with threaded joints and seal-offs
in Class I, Division 1 locations. EMT, PVC, and MC cable are not permitted in Division 1
unless specifically listed and approved. Group C requires explosionproof fittings.
8. A 100A, 120/240V panelboard is fed by a 2/0 AWG copper THWN feeder. If the
feeder is installed in a raceway with three other current-carrying conductors, what is
the adjusted ampacity of the feeder?
A. 150A
B. 130A
C. 120A
D. 100A
Answer: B. 130A
Rationale: NEC Table 310.15(B)(3)(a) for 4-6 current-carrying conductors requires an
80% adjustment. 2/0 AWG THWN at 75°C is rated 175A; 175A × 0.80 = 140A. However,
the next standard size is 130A after applying 240.4(B) if not a feeder for a specific load.
The correct adjusted ampacity is 130A.
Page 4 of 71
Examination with Practice Questions And
Correct Answers
1. A commercial service in Honolulu is supplied by a 120/208V, 3-phase, 4-wire system.
The calculated load is 180A continuous and 60A noncontinuous. If the service
disconnect is rated for 100% continuous operation, what is the minimum standard
ampere rating required?
A. 200A
B. 225A
C. 250A
D. 300A
Answer: C. 250A
Rationale: For a 100%-rated disconnect, the continuous load is not multiplied by 125%, so
total = 180A + 60A = 240A. The next standard size above 240A is 250A per NEC 240.6. A
200A or 225A device would be undersized; 300A is larger than necessary.
2. A 3-phase, 480V delta primary to 208Y/120V secondary transformer supplies a 150
kVA balanced load. If the primary conductors are copper with 75°C insulation and the
ambient temperature is 40°C, what is the minimum ampacity adjustment factor
applied to the primary conductor ampacity?
A. 0.88
B. 0.91
C. 0.94
D. 1.00
Answer: A. 0.88
Rationale: NEC Table 310.15(B)(2)(a) for 75°C conductors in a 40°C ambient gives a
correction factor of 0.88. The primary current is 150,000 / (480 × 1.732) 180A, and the
adjusted ampacity must be based on the 0.88 factor. Options B, C, and D correspond to
lower ambient temperatures or no adjustment.
Page 1 of 71
,3. A dwelling unit has a 200A, 120/240V service. The calculated load is 180A. If the
utility requires a minimum 100A service and the meter socket is rated 200A, what is
the minimum size copper grounding electrode conductor to a ground rod?
A. 6 AWG
B. 4 AWG
C. 2 AWG
D. 1/0 AWG
Answer: A. 6 AWG
Rationale: NEC Table 250.66 requires a 6 AWG copper grounding electrode conductor for
a 200A service when the service-entrance conductors are 2/0 AWG or smaller. A 4 AWG or
larger is only required for larger service conductors. Ground rod connection is further
permitted to be 6 AWG per 250.66(A).
4. In a commercial kitchen, a 208V, 3-phase, 12 kW deep fryer is connected to a 30A
branch circuit. If the equipment nameplate specifies a minimum circuit ampacity of
35A and maximum overcurrent protection of 40A, which of the following is the correct
conductor and breaker selection?
A. 10 AWG copper, 30A breaker
B. 8 AWG copper, 40A breaker
C. 10 AWG copper, 40A breaker
D. 8 AWG copper, 30A breaker
Answer: B. 8 AWG copper, 40A breaker
Rationale: The nameplate minimum circuit ampacity of 35A requires a conductor rated at
least 35A; 8 AWG copper at 75°C is rated 50A, while 10 AWG is only 35A at 75°C but may
be insufficient for continuous load. The maximum overcurrent protection of 40A dictates a
40A breaker. Thus 8 AWG copper with a 40A breaker is correct.
Page 2 of 71
,5. A 1,200 sq ft single-family dwelling in Hawaii has a 240V, single-phase service. The
calculated general lighting load is 3 VA per sq ft, and there are two 20A
small-appliance branch circuits and one 20A laundry circuit. Using the optional
method, what is the minimum service size?
A. 100A
B. 125A
C. 150A
D. 200A
Answer: B. 125A
Rationale: Using NEC 220.82 optional method: general lighting = 3,600 VA, small
appliance = 3,000 VA, laundry = 1,500 VA. Total = 8,100 VA. First 10,000 VA at 100% =
8,100 VA; demand = 8,100 VA. At 240V, 8, = 33.75A, but the minimum service is
100A. However, with a 240V service and typical dwelling, 125A is the next standard size
after applying demand factors and considering future loads. The correct minimum is 125A.
6. A 480V, 3-phase motor has a nameplate FLA of 52A. The motor is on a 75°C rated
circuit. What is the minimum size THWN copper conductor and the maximum rating
of the short-circuit and ground-fault protective device?
A. 6 AWG, 70A breaker
B. 6 AWG, 100A breaker
C. 4 AWG, 100A breaker
D. 4 AWG, 70A breaker
Answer: C. 4 AWG, 100A breaker
Rationale: NEC Table 430.250 for a 480V, 3-phase motor with 52A FLA requires
conductors with ampacity 52A × 1.25 = 65A. 6 AWG at 75°C is 65A, but 4 AWG is 85A and
is safer for voltage drop. The maximum breaker is typically 250% of FLA = 130A, but
standard size is 100A. Thus 4 AWG and 100A is correct.
Page 3 of 71
, 7. In a hazardous (classified) location, Class I, Division 1, Group C, which of the
following wiring methods is permitted for a 120V lighting circuit?
A. Rigid metal conduit with threaded joints and seal-offs
B. Electrical metallic tubing with compression fittings
C. PVC Schedule 80 conduit with solvent-welded joints
D. Type MC cable with an overall jacket
Answer: A. Rigid metal conduit with threaded joints and seal-offs
Rationale: NEC 501.10(A)(1) permits rigid metal conduit with threaded joints and seal-offs
in Class I, Division 1 locations. EMT, PVC, and MC cable are not permitted in Division 1
unless specifically listed and approved. Group C requires explosionproof fittings.
8. A 100A, 120/240V panelboard is fed by a 2/0 AWG copper THWN feeder. If the
feeder is installed in a raceway with three other current-carrying conductors, what is
the adjusted ampacity of the feeder?
A. 150A
B. 130A
C. 120A
D. 100A
Answer: B. 130A
Rationale: NEC Table 310.15(B)(3)(a) for 4-6 current-carrying conductors requires an
80% adjustment. 2/0 AWG THWN at 75°C is rated 175A; 175A × 0.80 = 140A. However,
the next standard size is 130A after applying 240.4(B) if not a feeder for a specific load.
The correct adjusted ampacity is 130A.
Page 4 of 71
