, Question 1
A residential service supplies a 1,200 sq ft dwelling with a 12 kW electric
range, a 5 kW clothes dryer, and a 3 kW water heater. Using the optional
method in NEC 220.82, what is the calculated demand load for the service?
A. 12.4 kW
B. 14.2 kW
C. 16.0 kW
D. 18.5 kW
Correct Answer: B - 14.2 kW
RATIONALE
Per NEC 220.82, total connected load = 12 + 5 + 3 = 20 kW. Apply
100% to first 10 kW and 40% to remainder: 10 + 0.4(10) = 14 kW,
then add 2 kW for the range (Table 220.55) yielding 14.2 kW. Options
A, C, and D misapply demand factors or omit the range adjustment.
Question 2
In a dwelling unit, a 20A branch circuit supplies a bathroom receptacle. Which
NEC requirement must be met regarding GFCI protection?
A. GFCI is required only if the receptacle is within 6 ft of a sink.
B. GFCI protection is required for all 125V, 15A and 20A receptacles in
bathrooms.
C. GFCI is optional if the circuit is dedicated to a single receptacle.
D. GFCI is required only for receptacles installed outdoors.
Correct Answer: B - GFCI protection is required for all 125V,
15A and 20A receptacles in bathrooms.
RATIONALE
NEC 210.8(A)(1) requires GFCI protection for all 125V, 15A and 20A
receptacles in dwelling unit bathrooms, regardless of proximity to a
sink. Options A, C, and D reflect outdated or incorrect interpretations.
Page 2
, Question 3
A 100A residential service uses a 2/0 AWG copper conductor for the
ungrounded service conductors. What is the minimum size copper grounding
electrode conductor required by NEC Table 250.66?
A. 6 AWG
B. 4 AWG
C. 2 AWG
D. 1/0 AWG
Correct Answer: B - 4 AWG
RATIONALE
NEC Table 250.66 specifies that for service conductors of 2/0 AWG
copper, the grounding electrode conductor must be at least 4 AWG
copper. Options A, C, and D are either too small or oversized per the
table.
Question 4
A 14 AWG copper conductor is used in a 20A branch circuit. Which NEC
section prohibits this installation?
A. NEC 240.4(D)(3)
B. NEC 210.19(A)(1)
C. NEC 310.15(B)(16)
D. NEC 250.122
Correct Answer: A - NEC 240.4(D)(3)
RATIONALE
NEC 240.4(D)(3) limits overcurrent protection for 14 AWG copper to
15A, so using it on a 20A circuit violates this section. Options B, C,
and D address voltage drop, ampacity, and equipment grounding,
respectively, but do not directly prohibit the 20A protection.
Page 3
, Question 5
In a Texas residential wiring project, a wireman's license is required for which
of the following tasks?
A. Replacing a light switch in a single-family home.
B. Installing a new 240V outlet for a dryer.
C. Performing maintenance on an existing electrical system under a
master electrician's supervision.
D. All of the above require a wireman license.
Correct Answer: D - All of the above require a wireman license.
RATIONALE
Under the Texas Electrical Safety and Licensing Act, a wireman
license is required for any electrical work, including replacements,
new installations, and maintenance, unless exempt. Options A, B, and
C individually describe tasks that indeed require licensure, making D
the comprehensive correct answer.
Question 6
A 3,000 sq ft dwelling has a 12 kW electric range and a 4.5 kW water heater.
Using the standard method (NEC 220.42-220.55), what is the calculated load
for the range?
A. 8 kW
B. 10 kW
C. 12 kW
D. 14 kW
Correct Answer: A - 8 kW
RATIONALE
NEC Table 220.55 permits a 12 kW range to be calculated at 8 kW
demand for a single range. Options B, C, and D incorrectly apply
demand factors or use the nameplate rating.
Page 4
A residential service supplies a 1,200 sq ft dwelling with a 12 kW electric
range, a 5 kW clothes dryer, and a 3 kW water heater. Using the optional
method in NEC 220.82, what is the calculated demand load for the service?
A. 12.4 kW
B. 14.2 kW
C. 16.0 kW
D. 18.5 kW
Correct Answer: B - 14.2 kW
RATIONALE
Per NEC 220.82, total connected load = 12 + 5 + 3 = 20 kW. Apply
100% to first 10 kW and 40% to remainder: 10 + 0.4(10) = 14 kW,
then add 2 kW for the range (Table 220.55) yielding 14.2 kW. Options
A, C, and D misapply demand factors or omit the range adjustment.
Question 2
In a dwelling unit, a 20A branch circuit supplies a bathroom receptacle. Which
NEC requirement must be met regarding GFCI protection?
A. GFCI is required only if the receptacle is within 6 ft of a sink.
B. GFCI protection is required for all 125V, 15A and 20A receptacles in
bathrooms.
C. GFCI is optional if the circuit is dedicated to a single receptacle.
D. GFCI is required only for receptacles installed outdoors.
Correct Answer: B - GFCI protection is required for all 125V,
15A and 20A receptacles in bathrooms.
RATIONALE
NEC 210.8(A)(1) requires GFCI protection for all 125V, 15A and 20A
receptacles in dwelling unit bathrooms, regardless of proximity to a
sink. Options A, C, and D reflect outdated or incorrect interpretations.
Page 2
, Question 3
A 100A residential service uses a 2/0 AWG copper conductor for the
ungrounded service conductors. What is the minimum size copper grounding
electrode conductor required by NEC Table 250.66?
A. 6 AWG
B. 4 AWG
C. 2 AWG
D. 1/0 AWG
Correct Answer: B - 4 AWG
RATIONALE
NEC Table 250.66 specifies that for service conductors of 2/0 AWG
copper, the grounding electrode conductor must be at least 4 AWG
copper. Options A, C, and D are either too small or oversized per the
table.
Question 4
A 14 AWG copper conductor is used in a 20A branch circuit. Which NEC
section prohibits this installation?
A. NEC 240.4(D)(3)
B. NEC 210.19(A)(1)
C. NEC 310.15(B)(16)
D. NEC 250.122
Correct Answer: A - NEC 240.4(D)(3)
RATIONALE
NEC 240.4(D)(3) limits overcurrent protection for 14 AWG copper to
15A, so using it on a 20A circuit violates this section. Options B, C,
and D address voltage drop, ampacity, and equipment grounding,
respectively, but do not directly prohibit the 20A protection.
Page 3
, Question 5
In a Texas residential wiring project, a wireman's license is required for which
of the following tasks?
A. Replacing a light switch in a single-family home.
B. Installing a new 240V outlet for a dryer.
C. Performing maintenance on an existing electrical system under a
master electrician's supervision.
D. All of the above require a wireman license.
Correct Answer: D - All of the above require a wireman license.
RATIONALE
Under the Texas Electrical Safety and Licensing Act, a wireman
license is required for any electrical work, including replacements,
new installations, and maintenance, unless exempt. Options A, B, and
C individually describe tasks that indeed require licensure, making D
the comprehensive correct answer.
Question 6
A 3,000 sq ft dwelling has a 12 kW electric range and a 4.5 kW water heater.
Using the standard method (NEC 220.42-220.55), what is the calculated load
for the range?
A. 8 kW
B. 10 kW
C. 12 kW
D. 14 kW
Correct Answer: A - 8 kW
RATIONALE
NEC Table 220.55 permits a 12 kW range to be calculated at 8 kW
demand for a single range. Options B, C, and D incorrectly apply
demand factors or use the nameplate rating.
Page 4
