NEC 2023 · checked by a second reviewer · November 7, 2026
NEC Article 314 Practice Questions (10 Free, With Answers)
Boxes and Box Fill: 10 original questions on box fill counts and volumes, box support and accessibility. Click an answer to see the explanation and the NEC section. No sign-up.
NEC Article 314 · 10 questions0 / 10 answered
A 14 AWG conductor passes through a box without a splice, but the installer leaves an unbroken loop 14 in. long inside the box. How much volume does this conductor count for? (14 AWG = 2.00 cu in.)
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Correct answer: B. An unbroken loop or coil at least twice the 6-in. free-conductor length (12 in. or more) counts twice. A conductor that simply passes straight through counts once, which is why 2.00 cu in. tempts, but a 14-in. loop meets the 'counted twice' rule.Reference: NEC 314.16(B)(1); NEC 300.14
A luminaire with a domed canopy has three 18 AWG fixture wires and an equipment grounding conductor that enter the outlet box and terminate there. How are they counted for box fill?
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Correct answer: C. Box fill allows up to four fixture wires smaller than 14 AWG, together with the EGC, to be left out when they come from a domed luminaire canopy and terminate in the box. Omitting only the EGC is tempting, but the exception covers both.Reference: NEC 314.16(B)(1) Exception
A box contains 12 AWG conductors that splice through to another outlet and 14 AWG conductors that connect to a single-pole switch on one yoke. What volume allowance does the switch need? (14 AWG = 2.00 cu in.; 12 AWG = 2.25 cu in.)
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Correct answer: D. Each yoke gets a double volume allowance based on the largest conductor connected to the device on that yoke, not the largest in the box. The switch connects to 14 AWG, so 2 x 2.00 = 4.00 cu in. 4.50 cu in. is tempting because 12 AWG is in the box, but it is not connected to the switch.Reference: NEC 314.16(B)(4)
Under NEC 2023, six 12 AWG equipment grounding conductors enter a box. What is the volume allowance for these EGCs? (12 AWG = 2.25 cu in.)
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Correct answer: C. One volume, based on the largest EGC, covers up to four EGCs, and each EGC beyond four adds one-quarter volume: 2.25 + (2 x 0.5625) = 3.375 cu in. 2.25 cu in. is tempting because through NEC 2017 a single allowance covered every EGC in the box, no matter how many there were. The quarter-volume rule started in NEC 2020 and is still in NEC 2023.Reference: NEC 314.16(B)(5)
An outlet box contains one luminaire stud and one hickey, and the largest conductor in the box is 14 AWG. What volume allowance do these fittings require? (14 AWG = 2.00 cu in.)
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Correct answer: B. Support fittings get one volume allowance for each type of fitting present, based on the largest conductor in the box. A stud and a hickey are two different types, so 2 x 2.00 = 4.00 cu in. 2.00 cu in. would be right if both fittings were studs, since fittings of the same type share one allowance.Reference: NEC 314.16(B)(3)
Inside a box, a short 12 AWG pigtail connects a receptacle to a wire-connector splice. No part of the pigtail leaves the box. How does it count for box fill?
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Correct answer: A. A conductor that is entirely inside the box (no part leaves it) is not counted. The conductors that enter the box and the device yoke are already counted, so the pigtail adds nothing. Counting it as one volume is the common mistake.Reference: NEC 314.16(B)(1)
In a wall finished with wood paneling (a combustible surface), how must a flush-type outlet box be installed?
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Correct answer: D. In combustible walls and ceilings, boxes, plaster rings or listed extenders must be flush with or project beyond the finished surface, so no wood is exposed to heat or arcing inside the box. The 1/4-in. setback is allowed only in walls and ceilings of noncombustible material.Reference: NEC 314.20
A ceiling outlet box installed exclusively for lighting must be able to support a luminaire weighing at least:
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Correct answer: C. Lighting outlet boxes must be able to support a luminaire of at least 50 lb. A heavier luminaire must be supported independently unless the box is listed and marked inside with the weight it can carry. 70 lb is tempting but is the limit for ceiling fan boxes.Reference: NEC 314.27(A)(2)
An outlet box listed and marked for use as the sole support of a ceiling-suspended (paddle) fan may support a fan weighing no more than:
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Correct answer: B. Boxes used as the sole support of a paddle fan must be listed and marked for that use, and they may not support fans over 70 lb. For fans over 35 lb, the marking must also state the maximum weight. 35 lb is tempting because it is the point where the weight marking becomes required, not the upper limit.Reference: NEC 314.27(C)
In an angle pull box with 4 AWG and larger conductors, a conductor enters through a 2-in. raceway and leaves through a 2-in. raceway on the adjacent wall. What is the minimum distance between these two raceway entries?
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Correct answer: A. For angle or U pulls, the distance between raceway entries enclosing the same conductor must be at least six times the trade size of the larger raceway: 6 x 2 in. = 12 in. 16 in. is tempting because it uses the eight-times multiplier from the straight-pull rule.Reference: NEC 314.28(A)(2)
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