Checked against primary sources 2026-08-24

A cable item turns on two things, the location and the building

Damp, wet, buried and subject to damage is one axis. Dwelling or not, and what the structure is permitted to be built of, is the other. Nonmetallic-sheathed cable is decided mostly by the second one.

Test yourself: 25 free questions on this topic

Sort by location, then sort by building

Running the location check alone is the standard way to lose a point on nonmetallic-sheathed cable, because Article 334 turns on what the structure is long before it turns on how wet the room is. Two lookups answer most cable items, and the building is the one candidates skip.

Dry, damp and wet are defined terms and the definitions do not track ordinary speech. A spot that feels dry can be classified damp, and the inside of a raceway run outdoors above grade is treated as a wet location even though nothing about it looks wet from the ground (NEC Article 100).

The building axis uses a completely different vocabulary: dwelling or not a dwelling, one and two family or multifamily, and what construction type the structure is permitted to be. Those words live in Article 334 and they have nothing to do with moisture. When a stem spends a clause on the building rather than on the room, that is the axis it wants.

The common types and their character

• Nonmetallic-sheathed cable. Cheap, common in dwellings, and fenced in more by what the building is than by what the room is. Article 334 carries a permitted list and a not-permitted list, and the second one is written so that it sends you back to the first.
• Metal-clad cable. Broader permitted uses, and whether the armor counts as an equipment grounding conductor turns on how that particular cable is built. Article 250 settles that, not Article 330.
• Armored cable. It looks like metal-clad on a job site and it is a separate article with separate answers, which is why items pair them.
• Underground feeder cable. The one in this group that goes straight in the ground, and even there it is the listing and marking that permit it rather than the name of the cable.
• Service entrance cable. Two styles, they are not interchangeable, and the permitted and not-permitted sections of Article 338 have to be read as a pair before either style is ruled in.

Metal-clad and armored being visually similar and legally different is the single most reliable distractor pair in this topic.

The cable articles, and what each cable is for

Six articles cover nearly everything a Texas paper asks about, and not one of their numbers moved this cycle. Informative Annex L maps the 2023 article numbers onto the 2026 ones, and every cable article comes across unchanged, so a tab set built on the article number still lands. What moved is inside the articles rather than on their spines.

• Armored cable, Type AC, is Article 320. Its scope covers the use, installation and construction specifications for armored cable, and the assembly with its bonding strip inside the interlocked armor is what separates it from the next entry.
• Metal-clad cable, Type MC, is Article 330, covering the use, installation and construction specifications of metal-clad cable. It carries the wider set of permitted uses of the two, and whether the sheath does the work of an equipment grounding conductor turns on how that particular cable is built, which Article 250 settles rather than Article 330.
• Nonmetallic-sheathed cable, Types NM and NMC, is Article 334. This is the one decided by what the building is rather than by how wet the room is, and its uses not permitted section is where the qualified sentences live.
• Power and control tray cable, Type TC, is Article 336. Permitted for power, lighting, control and signal circuits, in cable trays and in raceways, with the rest of its permissions attached to conditions you have to read.
• Service-entrance cable, Types SE and USE, is Article 338. Two type letters inside one article with different permitted uses, and that difference is usually what an item turns on.
• Underground feeder and branch-circuit cable, Type UF, is Article 340, covering the use, installation and construction specifications for underground feeder and branch-circuit cable. Burial depth is not in it. That comes from Article 300.

Three more sit alongside them and are worth recognizing rather than studying: mineral-insulated metal-sheathed cable, Type MI, at Article 332; instrumentation tray cable, Type ITC, at Article 335; and Type P cable at Article 337. All three appear in the Class I wiring method tables in Article 501, which is the only place a journeyman paper is likely to put them in front of you.

One thing worth knowing about the numbers themselves. Annex L also prints the article numbers planned for the 2029 edition, and every cable article carries a different one in that column. Nothing there changes an answer today. It does tell you what a tab set is worth across cycles, and why finding a rule by article title beats finding it by a number you memorized.

Uses Not Permitted is a list of qualified sentences

Almost every entry on one of these lists carries a qualifier that a summary drops, and the qualifier is usually the whole item. Article 334 shows the pattern cleanly.

• The commercial garage entry is not about commercial garages. It reaches commercial garages that have hazardous classified locations, and what counts as one of those is defined in another article entirely (NEC 334.12).
• The theater entry and the hazardous location entry both finish by pointing somewhere else, so each prohibition is only as wide as the article it defers to (NEC 334.12).
• The dropped ceiling entry is bounded by occupancy rather than by the ceiling. It reaches buildings that are not one- and two-family and not multifamily dwellings (NEC 334.12).
• The first entry is not a place at all. It bars the cable from any dwelling or structure that the permitted-use section did not name, so the two lists are one rule read from two directions (NEC 334.10, NEC 334.12).

The drill is the same for every prohibition on any of these lists. Find the sentence, read to the end of it including the clause that starts with "except", and then read whatever is printed underneath it. Exceptions in the NEC sit under the rule they modify, and an answer option built to look like a violation is often quoting the rule and ignoring what follows.

The same reading applies in reverse. A permitted-use paragraph can carry its own condition, and Article 334 attaches one to structures outside the dwelling categories, so being permitted in a building is not the same as being permitted anywhere in that building (NEC 334.10).

What Texas actually amends

One thing, and it has nothing to do with cable. The department adopts the 2026 National Electrical Code as approved by NFPA, effective 1 September 2026, and separately adopts NEC 210.8(F) Exception No. 2 without the expiration date the national text puts on it (16 TAC 73.100).

That matters here for a negative reason. The permitted and not-permitted sections in Articles 320, 330, 334, 338 and 340 are the national text with nothing sitting on top of them, so there is no state version to hunt for and no state rule that will rescue a wrong reading of a prohibition.

City ordinances are a separate question and they do not follow you into the exam room. The examinations are referenced to the adopted edition, and from 1 September 2026 that is the 2026 edition.

What a question is actually asking

• Names a location. Classify it against the Article 100 definitions first, then open the permitted-use section.
• Names the occupancy, the dwelling type or the construction type. That is an Article 334 item even if the stem never uses the word nonmetallic.
• Names two similar cables. It wants the distinction, and the distinction usually lives in the not-permitted section rather than the permitted one.
• Mentions burial. The question is which cables are listed and identified for direct burial, which is a marking question rather than a material question.
• Mentions a raceway with cable inside it. It may be a fill question wearing a costume, and a cable in a raceway is not counted the way loose conductors are.
• Mentions a function rather than a place, such as using a cable as a service entrance. Several prohibitions are written against the job the cable is doing, not against the room it is in.

One 2026 change that is easy to walk past

The cable articles now put three things in the same listing sentence: the cable, the fittings that connect it, and the cable ties, staples, straps and hangers that hold it up. The hardware being a listed product identified for the use is the new part, and it reads like a detail until an item describes the fastener rather than the spacing.

It is worth a tab because it changes what a stem can be about. An installation can be at the right intervals, in a permitted location, in a permitted building, and still be described in a way that puts the whole question on the staple.

Questions people ask

What are the cable types the exam asks about?

The code has no such thing as a cable class, so the useful list is the articles. Armored cable Type AC at Article 320, metal-clad cable Type MC at Article 330, nonmetallic-sheathed cable Types NM and NMC at Article 334, power and control tray cable Type TC at Article 336, service-entrance cable Types SE and USE at Article 338, and underground feeder and branch-circuit cable Type UF at Article 340. Mineral-insulated Type MI at Article 332, instrumentation tray cable Type ITC at Article 335 and Type P at Article 337 turn up mainly in the hazardous location tables. Every one of those articles carries its own uses permitted and uses not permitted sections, and that pair is where the items come from.

What decides whether a cable is permitted where you want to use it?

Two lookups, and candidates skip the second one. The first is the location, because dry, damp and wet are defined terms in Article 100 and they do not track ordinary speech. The second is the building, and for nonmetallic-sheathed cable it is the lookup that decides the answer, because Article 334 turns on whether the structure is a dwelling and on what construction type it is permitted to be. When a stem spends a clause on the building rather than on the room, that is the axis it wants.

What article covers NM cable?

Article 334, which covers the use, installation and construction specifications of nonmetallic-sheathed cable and reaches both Type NM and Type NMC. Its uses permitted section at 334.10 and its uses not permitted section at 334.12 are where the exam lives. Almost every entry on the second list carries a qualifier that a summary drops: the commercial garage entry, for instance, reaches commercial garages having hazardous classified locations rather than commercial garages in general.

What is the difference between MC and AC cable?

They are separate articles with separate rules and they look similar in the hand, which is what makes them a reliable distractor pair. Armored cable Type AC is Article 320 and metal-clad cable Type MC is Article 330, and MC carries the wider set of permitted uses. Whether the armor or sheath counts as an equipment grounding conductor depends on how that particular cable is built, and it is settled in Article 250 rather than in either cable article. Read which type the stem named before anything else.

Which cable goes underground?

Type UF, underground feeder and branch-circuit cable, at Article 340, with Type USE inside Article 338 on the service side. Burial depth is in neither article: it comes from Article 300, and 300.7(B) also makes the interior of an enclosure or raceway installed underground a wet location. A stem that mentions burial is asking two questions at once, which cable is listed for the use and how deep it goes, and they are answered from different places in the book.

Did the cable article numbers change in the 2026 NEC?

No. Informative Annex L maps the 2023 article numbers onto the 2026 ones and Types AC, MC, NM, TC, SE and UF all keep the numbers they had. What changed sits inside the articles, including the listing sentence that now covers the cable, its fittings, and the cable ties, staples, straps and hangers holding it up. Annex L also prints the numbers planned for the 2029 edition, and every cable article carries a different one there.

What this page cites

• NEC 334.10 Nonmetallic-sheathed cable, uses permitted. The paragraphs turn on dwelling type and on construction type, and one of them carries a condition on how the cable is installed. Read it in your own copy of the 2026 edition, because the prohibition section points back at named paragraphs of it. source
• NEC 334.12 Uses not permitted, the section people skip. Ten paragraphs in subsection (A), most of them qualified by an occupancy, a classification, or a cross reference to another article that narrows them. source
• NEC 330.10 Metal-clad cable, uses permitted. Pair it with 330.12 and with Article 250 for the separate question of whether the armor is an equipment grounding conductor. source
• NEC Article 100 Definitions of dry, damp and wet locations. These are the terms the permitted-use sections are written in, so the definition decides the item before the cable article does. source
• 16 TAC 73.100 Texas adoption of the 2026 National Electrical Code, effective 1 September 2026, with a single amendment concerning NEC 210.8(F) Exception No. 2. No cable article is amended. Rule text as published by the Texas Secretary of State. source
• PSI candidate information bulletin, TDLR electrical examinations Updated 9 July 2026. States in capitals that effective September 1, 2026 the examinations will be referenced to the 2026 NEC. source