Cable types on the Texas exam, and the second lookup that decides the answer

What the exam asks here

Eleven of the 500 questions in our bank name a cable type or a cable article. Nine of them sit in wiring methods and installations, and two more turn up in grounding, where a nonmetallic sheathed run is the setting for a question about equipment grounding conductors in a box.

Four question shapes account for nearly all of them. One names a location and waits to see whether you classify it against the Article 100 definitions before opening a cable article. One names an occupancy, a dwelling type or a construction type, which makes it a nonmetallic sheathed cable item even where the stem never uses the word. One names two cables that look alike in the hand and wants the distinction between them. One names a job the cable is being asked to do, such as running underground or crossing a space carrying environmental air.

The distractor data is consistent. On the item about a two story wood framed dwelling and a three story building of noncombustible construction, the popular miss counts floors, because the cable article ties its permitted uses to construction type and carries no story limit to read off. On the corrosive farm building item, the popular miss reaches for a temperature difference between two cables that share the same ampacity limit. Both misses come from a summary that dropped a qualifier.

Location first, then the 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.

Dry, damp and wet are defined terms in Article 100 and the definitions depart from ordinary speech. A spot that feels dry can be classified damp, and the inside of a raceway run outdoors above grade is a wet location even though nothing about it looks wet from the ground. The bank tests that directly: conduit breathes with the temperature and condenses inside, so conductors pulled into it have to be listed for wet locations. Our page on conductor insulation types takes the conductor side of that.

The building axis uses a separate vocabulary. Dwelling or otherwise, 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, that is the axis it wants. The article permits nonmetallic sheathed cable in one and two family dwellings with their attached garages and storage buildings with no reference to construction type at all, while construction type governs everywhere else, and construction type comes out of the building code.

The articles worth a tab

Six articles cover nearly everything a Texas paper asks about, and none of their numbers moved this cycle. Informative Annex L maps the 2023 numbers onto the 2026 ones and every cable article comes across unchanged, so a tab set built on an article number still lands.

Three more sit alongside them and are worth recognising: 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 where a journeyman paper puts them in front of you. Annex L also prints the numbers planned for the 2029 edition, where every cable article carries a different one.

Every prohibition carries a qualifier

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

• The commercial garage entry reaches commercial garages that have hazardous classified locations, and what counts as one of those is defined in another article.
• 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.
• The dropped ceiling entry is bounded by occupancy, reaching buildings outside the one and two family and multifamily categories.
• The first entry names no place at all. It bars the cable from any dwelling or structure the permitted use section left unnamed, so the two lists are one rule read from two directions.

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. Exceptions in the code sit under the rule they modify, and an answer option built to look like a violation is often quoting the rule while ignoring what follows it. The same reading applies in reverse, since a permitted use paragraph can carry its own condition, and being permitted in a building differs from being permitted anywhere in that building.

One 2026 change worth catching

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.

That change gives a stem somewhere new to go. An installation can be at the right intervals, in a permitted location and in a permitted building, and still be described in a way that puts the whole question on the staple. The bank already works that angle from the other side, with an item on a cable secured by staples driven hard enough to flatten the jacket. The securing paragraphs carry two ideas, the interval and the manner, and a staple driven through a jacket damages insulation at a point nobody will ever see again.

What Texas amends, and what it leaves alone

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, under 16 TAC 73.100.

That matters here for a quiet 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. The PSI candidate information bulletin updated 9 July 2026 says the examinations are referenced to the 2026 edition from the same date.

Where the bank puts its traps

Five bank items are worth studying as a group, since each carries a distinction that survives a rewrite.

• Nonmetallic sheathed cable run exposed in an unfinished basement: the split is on the stiffness of the assembly, since a larger cable can take being fastened across the face of the joists while a smaller one goes through bored holes or onto a running board.
• A dropped ceiling cavity used as a return air path: the space carries environmental air, which limits the methods to metal raceways, metal clad cable without a nonmetallic covering, and cables listed for the use.
• A damp and corrosive farm building: the letter C is the whole of the difference, because the C version carries a jacket built to sit in those conditions while both cables share the same conductor temperature limit for ampacity.
• Type MI in places that keep other cables out: nothing in the assembly is organic, so it holds up at temperatures that destroy thermoplastic insulation and keeps working during a fire.
• A Type TC cable marked ER: the suffix records a crush and impact test, letting the cable leave the tray for a limited exposed run under conditions on support.

A sixth pattern reaches across areas. An item mentioning a raceway with cable inside it may be a fill question wearing a costume, and our conduit and raceways hub is where that calculation lives.

What to do about it before test day

The Texas examination is open book and you bring your own current copy, so the value of preparation here is in how fast you can reach a sentence.

• Tab by article title as well as by number, since Annex L shows every cable article moving again for 2029 while the titles hold still.
• Put a tab on the Article 100 definitions of dry, damp and wet, because the definition decides the item before the cable article does.
• Tab 334.10 and 334.12 as a pair. The prohibition section points back at named paragraphs of the permitted use section, so reading either one alone leaves the question half answered.
• Write the two lookups in the margin at the front of Chapter 3: classify the location, then classify the building.
• Read one full uses not permitted section end to end, including the clauses beginning with except and anything printed underneath.

the question set carries the code side of the same topic, with the article scopes set out and each prohibition traced to its section, at the question set, which is where the worked detail sits. Cable choice also feeds the ampacity work, and our page on ampacity derating picks it up from there.

Questions people ask

What decides whether a cable may be used where you want 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 depart from 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, that is the axis it wants, and the room is a secondary question.

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 items come from. 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, and the dropped ceiling entry is bounded by occupancy. Read both sections as a pair, since each one points at the other.

What is the difference between MC and AC cable?

They are separate articles with separate rules and they look similar in the hand, which makes them the most reliable distractor pair in this topic. Armored cable Type AC is Article 320 and metal clad cable Type MC is Article 330, and Type 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 Article 250 is where that gets settled. 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 lives in neither article and comes from Article 300, which 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 and identified for the use and how deep it goes, and they are answered from different places in the book. A wet location rating on a conductor answers a different question again.

Did the cable article numbers change in the 2026 NEC?

No. Informative Annex L maps the 2023 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, where every cable article carries a different one, which is a reason to tab by article title as well as by number.

Does Texas amend any of the cable articles?

No. Under 16 TAC 73.100 the department adopts the 2026 National Electrical Code as approved by NFPA effective 1 September 2026, with one amendment that keeps NEC 210.8(F) Exception No. 2 alive past the expiration date in the national text. The permitted and not permitted sections in Articles 320, 330, 334, 338 and 340 stand as the national text. City amendments are a separate matter under Tex. Occ. Code 1305.201, and they bind work inside the corporate limits while the examination stays referenced to the state adopted edition.