Boxes and Conduit Bodies Practice Questions

C. A separate portion of a conduit or tubing system giving access through a removable cover at a junction of two or more sections or at a terminal point

The definition ties the enclosure to the raceway system it is part of, at a junction or at a terminal point, with access through a removable cover. The same definition adds that FS and FD boxes, and larger cast or sheet metal boxes, are not classified as conduit bodies. That last sentence decides items where a stem calls an FD box a conduit body to see whether you will follow along.

NEC 2026 Article 100

D. 300.17

The general requirement sits at 300.17 in the 2026 book, having been 300.15 in the edition before it. Its neighbor moved too: the free conductor rule that used to be 300.14 is now 300.16. In an open book exam the navigation is the part that costs minutes, so the safe habit is to find requirements by part title and heading rather than by an address you memorized from an older book.

NEC 2026 300.17

A. No conductor is spliced or terminated inside it, and where it serves as a pull point it stays accessible after installation

Two conditions travel together in that subdivision: nothing spliced and nothing landed inside, and if it is doing the job of a pull point, you can still get at it once the building is finished. An item on this topic usually describes an installation with no box in it and asks whether that is acceptable, which means the answer lives in an exception rather than in the general sentence. Size and location listing are conditions from other rules entirely.

NEC 2026 300.17(F)

B. 1/4 inch

The sheath extends not less than a quarter inch inside the box, and the same quarter inch beyond the end of any cable clamp. The reason is abrasion: the point where the conductors leave the sheath is the vulnerable spot, and it belongs inside the enclosure. That quarter inch shows up in several places in this article, so check which one a stem is asking about before you answer.

NEC 2026 314.17(B)(2)

D. Where the cable is fastened within 8 inches of the box measured along the sheath and the sheath extends through the knockout at least a quarter inch

The exception carries a box size, a fastening distance measured along the sheath, and a sheath extension, and all three have to be true together. The distance is 8 inches measured along the sheath rather than the 12 inches people carry from the cable article. Multiple cable entries through one knockout are permitted under the same exception, which is the part that makes it practical.

NEC 2026 314.17(B)(2)

C. Its cross sectional area is at least twice that of the largest conduit or tubing it can be attached to, and the conductor count comes from the conduit fill table

Used purely as a pull point, a conduit body is sized against the raceway rather than against the conductors, and both comparisons come out of conduit fill rather than out of volume. There is no cubic inch total anywhere in that branch and no conductor count in the box fill sense. That is a clean decision rather than a judgment call, and it turns on whether anything is spliced, tapped or mounted inside.

NEC 2026 314.16(C)(1)

B. The manufacturer has durably and legibly marked it with its volume

The marking is the gate. Only a conduit body marked by its manufacturer with its volume is permitted to contain a splice, a tap or a wiring device, and once it does, the conductor count comes from the box fill calculation. The raceway area comparison does not disappear when the splice arrives; box fill is added to it rather than substituted for it.

NEC 2026 314.16(C)(2)

A. Short radius bodies of that kind are not permitted to contain splices, taps or wiring devices at all

Capped elbows and service entrance elbows exist only to let you install the raceway and pull the conductors through, and the subsection says they do not get a splice, a tap or a wiring device whatever they are marked with. A stem describing a splice in one of them is describing a violation rather than a sizing problem. The volume marking is a distractor in that scenario, not the answer.

NEC 2026 314.16(C)(3)

D. Whether the conductors it encloses reach 4 AWG

Conductor size is the first fork and it is sharp, because there is no trade size between 6 AWG and 4 AWG for anything to fall into. Boxes and conduit bodies enclosing 4 AWG or larger comply with the pull and junction box section, which sizes from geometry rather than from volume. Whether a device is mounted matters, but only on the 6 AWG and smaller branch and only for conduit bodies.

NEC 2026 314.16, 314.28

B. 12 inches

An angle pull, a U pull or a splice measures six times the trade size of the largest raceway in the row, so six times 2 inches gives 12 inches. The eight times multiplier belongs to a straight pull and produces the 16 inches offered here. Sketching the enclosure with its raceways first is what tells you which case you are in, because the case follows from the picture rather than from the wording.

NEC 2026 314.28(A)(2)

C. 22 inches

Start with six times the largest raceway in the row, which is 18 inches, then increase it by the sum of the diameters of all the other entries in that same row on that same wall, which is 2 plus 2, or 4 inches. That gives 22 inches. Each row is figured on its own and the row producing the greatest distance is the one used, so a box with entries on several walls needs the calculation run more than once.

NEC 2026 314.28(A)(2)

A. Not less than six times the trade size of the larger raceway

The section gives both the enclosure dimension and the distance between entries carrying the same conductor, and the second one is six times the trade size of the larger raceway. Items are written to hand you both numbers and see which one you report, so read whether the question wants the box dimension or the spacing. The wrong one of the two is always among the choices.

NEC 2026 314.28(A)(2)

B. Each section is considered a separate box

A permanent barrier in a pull or junction box makes each section a separate box, so the pull distances get worked out section by section. A box that satisfies the multipliers overall can easily have one section that does not. That is the same idea the box fill rules use when they calculate each barriered space separately.

NEC 2026 314.28(D)

A. The one for raceway supported enclosures without devices, luminaires or lampholders

The line in the support section is not spliced against unspliced. It is device against no device, and wire connectors and other splicing devices sit on the no device side of it. Putting a splice inside an enclosure does not move it into the stricter subsection, which is the single most common wrong belief on this topic.

NEC 2026 314.23(E)

D. Within 18 inches

The general figure is 3 feet, and it tightens to 18 inches where every conduit entry is on the same side, because a one sided arrangement is a cantilever. The same subsection caps the enclosure at 100 cubic inches and asks for threaded entries or identified hubs with two or more conduits threaded wrenchtight. Grabbing the 3 feet without reading the same side condition is what this item is built on.

NEC 2026 314.23(E)

C. Intermediate metal conduit, rigid metal conduit, PVC, RTRC and electrical metallic tubing

The 2026 edition lists five methods here, and it also widened what the exception covers to include an FS or FD single gang device box and an explosionproof outlet box of any size with one or more entries. Read that list in your own book rather than from an older summary, because the shorter versions are the ones most published material still prints. The stricter subsection for enclosures with devices narrows the same idea to two methods.

NEC 2026 314.23(E)

D. Mounting a device other than a splicing device in it, or hanging a luminaire or lampholder off it

The trigger is what is mounted in or on the enclosure, not what is joined inside it. Add a device that is not a splicing device, or support a luminaire or lampholder, and the securing distance tightens and the single raceway exception narrows. Same enclosure, same raceway, different answer, decided by the contents rather than by the splice.

NEC 2026 314.23(E), 314.23(F)

B. Rigid metal conduit or intermediate metal conduit

The exception on the stricter side allows a single rigid metal or intermediate metal conduit and no others, and it names what it may support: a conduit body no larger in trade size than the conduit, an FS or FD single gang device box, or a single gang explosionproof outlet box of any size. The looser subsection permits five methods, so exporting that list here is the mistake. Threaded metal is what carries a device and its weight on one raceway.

NEC 2026 314.23(F)

A. Not more than 100 cubic inches

The suspended ceiling subsection caps the enclosure at 100 cubic inches and then gives two ways to fasten it: to framing members by bolts, screws, rivets or identified clips, or to ceiling support wires that are taut and fastened at each end. The 100 cubic inch figure is the same ceiling that appears in the raceway support subsections, which makes it worth remembering once. The other numbers are box volumes from the metal box table, put there to look familiar.

NEC 2026 314.23(D)

C. The ability to get to the wiring and devices inside without removing part of the structure or the finish

The test is about the contained wiring and devices, and it is written against the finished building rather than against the installer at rough-in. If getting to the conductors means taking out part of the structure or the finish, the enclosure is not accessible. Underground enclosures are handled separately, so read what sits under the general sentence before calling a buried installation a violation.

NEC 2026 314.29

D. 1/2 inch

A box with nothing in it but conductors gets a floor of half an inch. Once a device or utilization equipment goes in, the depth is driven by the rearward projection of the equipment and by the size of the conductors supplying it, and the section gives a figure for each conductor range. Extension boxes, plaster rings and raised covers count toward that internal depth.

NEC 2026 314.24(A)

A. 2-1/16 inches

Conductors of 8, 6 or 4 AWG put the box in one band with a depth floor of 2-1/16 inches. The bands below it are 1-3/16 inches for 12 or 10 AWG and 15/16 inch for 14 AWG and smaller, which is why those two numbers are sitting in the choices. The 2-1/8 inches is a box depth from the metal box table rather than a requirement from this section.

NEC 2026 314.24(B)(3)

C. 50 pounds

A ceiling outlet used only for lighting is required to support a luminaire weighing at least 50 pounds. Above that weight the luminaire is supported independently of the box unless the box is listed for the load and marked on the interior with the maximum weight. The 35 and 70 pound figures belong to the paddle fan rules, and the 6 pounds is the small luminaire case on a vertical surface.

NEC 2026 314.27(A)(2)

B. Listed, marked on the interior as suitable for the purpose, marked with the maximum weight if it supports more than 35 pounds, and supporting no more than 70 pounds

Three conditions travel together for a box or box system used as the sole support of a fan, and the two weight figures are 35 pounds for the marking trigger and 70 pounds for the hard ceiling. The 50 pound figure belongs to the luminaire rule, which is why it reads plausibly here. Read which object the scenario describes before reaching for a number.

NEC 2026 314.27(B)(1)

A. A cover, faceplate, lampholder or luminaire canopy

Each box gets a cover, faceplate, lampholder or luminaire canopy, with a narrow exception for an installation covered by the luminaire article. A conduit body is finished with a cover, a lampholder or a device. Metal covers and plates are permitted, and where they are used they get connected to the equipment grounding conductors.

NEC 2026 314.25