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Question 1: According to NEC 2023, what is the minimum ampacity required for a
branch circuit supplying a single 12 kW electric range in a dwelling unit?
A. 30 amperes
B. 40 amperes
C. 50 amperes
D. 60 amperes
CORRECT ANSWER: B. 40 amperes
Rationale: NEC Table 220.55, Column C permits a demand factor for household
electric ranges. For a single range rated at 12 kW, the demand load is 8 kW. Using P = E ×
I, 8,000W ÷ 240V = 33.3A. NEC 210.19(A)(3) requires branch-circuit conductors to have
an ampacity of not less than the load served. The next standard overcurrent device per
240.6(A) is 40A, which is the minimum required circuit rating.
Question 2: Which NEC article specifically addresses the requirements for
grounding and bonding of electrical systems?
A. Article 200
B. Article 250
C. Article 310
D. Article 430
CORRECT ANSWER: B. Article 250
Rationale: NEC Article 250 is titled "Grounding and Bonding" and contains
comprehensive requirements for grounding electrical systems, equipment grounding,
bonding of non-current-carrying metal parts, and grounding electrode systems. Article
200 covers general requirements for grounding, Article 310 addresses conductors, and
Article 430 covers motors.
Question 3: What is the maximum number of 12 AWG THHN conductors permitted
in a ¾-inch EMT conduit according to NEC Chapter 9, Table 1 and Annex C?
A. 10
B. 12
C. 16
D. 20
CORRECT ANSWER: C. 16
,Rationale: Per NEC Chapter 9, Annex C, Table C.1, a ¾-inch EMT conduit permits a
maximum of 16 conductors of 12 AWG THHN when all conductors are the same size
and insulation type. This calculation is based on the 40% fill allowance for more than
two conductors per Chapter 9, Table 1, combined with the cross-sectional area of 12
AWG THHN from Chapter 9, Table 5.
Question 4: When calculating the total load for a dwelling unit service, what
demand factor applies to the first 3,000 VA of general lighting and general-use
receptacle load?
A. 35%
B. 50%
C. 100%
D. 75%
CORRECT ANSWER: C. 100%
Rationale: NEC 220.42 specifies the lighting load demand factors for dwelling units.
The first 3,000 VA of the general lighting and general-use receptacle load is calculated at
100%. The next 3,001 to 120,000 VA is calculated at 35%, and any load over 120,000 VA
is calculated at 25%.
Question 5: What is the minimum required working space width in front of
electrical equipment rated 600 volts or less, according to NEC 110.26(A)(2)?
A. The width of the equipment or 30 inches, whichever is greater
B. 36 inches minimum
C. 42 inches minimum
D. The width of the equipment only
CORRECT ANSWER: A. The width of the equipment or 30 inches, whichever is
greater
Rationale: NEC 110.26(A)(2) states that the work space shall be at least 30 inches wide
or the width of the equipment, whichever is greater. This ensures adequate space for
safe operation and maintenance of electrical equipment, with additional requirements
for depth and height specified in 110.26(A)(1) and (A)(3).
Question 6: For a 20-ampere branch circuit supplying receptacles in a dwelling unit
kitchen, what is the minimum number of small-appliance branch circuits required
by NEC 210.11(C)(1)?
A. One 20-ampere circuit
B. Two 20-ampere circuits
C. One 15-ampere and one 20-ampere circuit
D. Three 20-ampere circuits
CORRECT ANSWER: B. Two 20-ampere circuits
,Rationale: NEC 210.11(C)(1) requires that in dwelling units, at least two 20-ampere
small-appliance branch circuits be provided for all receptacle outlets specified in
210.52(B) for the kitchen, pantry, breakfast room, dining room, or similar areas. These
circuits shall have no other outlets.
Question 7: What is the maximum allowable voltage drop for a branch circuit as
recommended by NEC informational note in Article 215.2(A)(3)?
A. 2%
B. 3%
C. 5%
D. 10%
CORRECT ANSWER: B. 3%
Rationale: While NEC does not enforce voltage drop as a mandatory requirement, the
informational note in 215.2(A)(3) recommends that the maximum voltage drop for a
branch circuit should not exceed 3% for reasonable efficiency of operation. The
combined voltage drop for feeder and branch circuit should not exceed 5%.
Question 8: Which type of ground-fault circuit interrupter (GFCI) protection is
required for all 125-volt, single-phase, 15- and 20-ampere receptacles installed in a
residential garage according to NEC 210.8(A)(2)?
A. GFCI protection at the panel only
B. GFCI protection at each receptacle or at the circuit breaker
C. No GFCI protection required
D. AFCI protection only
CORRECT ANSWER: B. GFCI protection at each receptacle or at the circuit breaker
Rationale: NEC 210.8(A)(2) requires GFCI protection for all 125-volt, single-phase, 15-
and 20-ampere receptacles installed in garages of dwelling units. This protection may
be provided by a GFCI circuit breaker, a GFCI receptacle, or a GFCI device protecting
downstream receptacles.
Question 9: What is the minimum size equipment grounding conductor required for
a 60-ampere circuit using copper conductors, per NEC Table 250.122?
A. 10 AWG copper
B. 8 AWG copper
C. 6 AWG copper
D. 12 AWG copper
CORRECT ANSWER: A. 10 AWG copper
Rationale: NEC Table 250.122 specifies the minimum size equipment grounding
conductors based on the rating of the overcurrent device. For a 60-ampere overcurrent
device, the table requires a minimum 10 AWG copper equipment grounding conductor.
Aluminum or copper-clad aluminum would require 8 AWG.
, Question 10: According to NEC 314.16, how many cubic inches of box fill volume is
required for each 12 AWG conductor entering a junction box?
A. 1.75 cubic inches
B. 2.00 cubic inches
C. 2.25 cubic inches
D. 2.50 cubic inches
CORRECT ANSWER: C. 2.25 cubic inches
Rationale: NEC Table 314.16(B) specifies the volume allowance required per conductor
based on conductor size. For 12 AWG conductors, each conductor requires 2.25 cubic
inches of free space within the box. This calculation is essential for determining proper
box sizing to prevent conductor damage and ensure safe installations.
Question 11: What is the minimum burial depth for direct-buried UF cable
supplying a residential outdoor lighting circuit at 120 volts, according to NEC Table
300.5?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
CORRECT ANSWER: B. 12 inches
Rationale: NEC Table 300.5, Column 4 specifies that for direct-buried cables or
conductors supplying residential branch circuits rated 120V to 600V with GFCI
protection and maximum overcurrent protection of 20A, the minimum cover
requirement is 12 inches. UF cable is listed for direct burial applications.
Question 12: When sizing conductors for a continuous load, NEC 210.19(A)(1)
requires the branch-circuit conductors to have an ampacity of at least what
percentage of the continuous load?
A. 100%
B. 110%
C. 125%
D. 150%
CORRECT ANSWER: C. 125%
Rationale: NEC 210.19(A)(1) requires that branch-circuit conductors supplying
continuous loads (loads expected to operate for 3 hours or more) shall have an
ampacity of not less than 125% of the continuous load. This requirement ensures
conductors do not overheat under sustained operation.
Question 13: Which NEC article covers the installation requirements for motors
and motor circuits?