Free NEC practice test · Article 722

Power-Limited Circuit Cables practice questions

A free NEC Article 722 practice test for the journeyman exam: 15 questions on Cables for Power-Limited Circuits and Fault-Managed Power Circuits, each with the answer and the why behind it.

15 questions · free · answers included NEC 2023 · Updated

How to use this practice test

These 15 journeyman-exam practice questions cover NEC Article 722 across 15 code concepts, every one with the correct answer and a plain-English explanation of the rule behind it. They come from the same question bank the Loomi app trains you on — this is the free web sample, not a separate watered-down set.

Work straight down the sheet and answer before you peek: each question hides its answer behind Show answer & explanation. Questions tagged Code lookup are speed drills — race your codebook to the cited section. Printing this page gives you a clean paper worksheet with the answers left off.

Class 2/Class 3 and PLFA cable voltage, sizing, and temperature ratings

NEC 722.179(A)(14)

Class 2 cable needs at least 150V, Class 3 and PLFA cable need at least 300V, and all three need at least a 60°C rating.

Q1 NEC 722.179(A)(14) Code lookup

A low-voltage installer is selecting a Class 3 cable for a burglar alarm circuit and needs to confirm the minimum voltage and temperature ratings the cable must carry per its listing. Which section specifies these ratings?

  1. A 722.179(A)(8)
  2. B 722.179(A)(16)(3)
  3. C 722.179(A)(14)
  4. D 722.179(A)(15)
Show answer & explanation

Correct: C — 722.179(A)(14)

722.179(A)(14) sets the minimum voltage rating (150V for Class 2, 300V for Class 3) and minimum 60°C temperature rating for Class 2/3 cables. 722.179(A)(15) covers the same ratings but for PLFA cable specifically, and 722.179(A)(16)(3) covers Class 4 cable voltage rating only, not Class 2/3.

Fire-resistance hierarchy: plenum, riser, general-purpose, alternative general-purpose

NEC 722.179(A)(1)

Plenum cable is the highest-rated tier and can substitute anywhere below it, but general-purpose cable can never go into ducts, plenums, or risers.

Q2 NEC 722.179(A)(1)

A contractor needs to run cable through an air-handling plenum space above a suspended ceiling. Which cable listing is required?

  1. A Riser cable
  2. B Plenum cable
  3. C General-purpose cable
  4. D Alternative general-purpose cable
Show answer & explanation

Correct: B — Plenum cable

Per 722.179(A)(1), only plenum cable is listed as suitable for ducts, plenums, and other spaces for environmental air, with fire-resistant, low-smoke characteristics. Riser cable is rated for vertical shafts, not plenums, and both general-purpose and alternative general-purpose cable are explicitly excluded from plenum use under 722.179(A)(3) and 722.179(A)(4).

Field-assembled and composite optical fiber cable listing

NEC 722.179(A)(12)

Field-assembled fiber cable needs a matched, cross-marked jacket-and-fiber pair; composite cables with electrical conductors are listed as electrical cable, not as fiber cable.

Q3 NEC 722.179(A)(12)

A single cable assembly contains both copper power conductors and optical fibers. Under 722.179(A)(13), how is this composite cable listed?

  1. A As an electrical cable, based on the type of electrical conductors it contains
  2. B As an optical fiber cable, based on the fiber type present
  3. C As a communications raceway, based on the jacket construction
  4. D It cannot be listed as one cable; conductors and fibers must be jacketed separately
Show answer & explanation

Correct: A — As an electrical cable, based on the type of electrical conductors it contains

722.179(A)(13) states composite optical fiber cables are listed as electrical cables based on the type of electrical conductors — the fiber content doesn't drive the listing, it isn't treated as a raceway, and combining fibers with conductors in one cable is explicitly contemplated, not prohibited.

Equipment access and workmanlike cable installation/support

NEC 722.24(A)

Class 2/3 cable runs can never block access to panels behind them, and every cable must be supported by the building structure with proper hardware — never taped or strapped to the outside of a raceway.

Q4 NEC 722.24(A) Code lookup

A residential low-voltage installer runs Class 2 speaker cable exposed across the top of a suspended ceiling, then straps it directly to the outside of an EMT raceway that also runs through that space to save on separate supports. Which section addresses whether the cable can be supported this way?

  1. A 722.3(E)
  2. B 722.24(C)
  3. C 722.24(B)
  4. D 722.24(A)
Show answer & explanation

Correct: C — 722.24(B)

722.24(B) specifically prohibits strapping, taping, or attaching cables to the exterior of a conduit or raceway as a means of support. 722.24(A) covers general workmanlike installation and securing to the building structure, not attachment to raceways, so it's the closer but wrong distractor.

Raceway sizing, fire spread, and air-handling space rules for power-limited cables

NEC 722.3

Article 722 power-limited circuits borrow their raceway, fire-stop, plenum, tray, and temperature rules straight from Articles 300, 392, and 335 — Article 722 itself sets none of those numbers.

Q5 NEC 722.3

A contractor wants to run power-limited cable through a plenum used for environmental air without installing it in metal raceway. Under 722.3(C), what makes this permitted?

  1. A The cable is selected in accordance with Table 722.135(B)
  2. B The cable is listed instrumentation tray cable per 335.1
  3. C The installation complies with 300.7(A) for temperature exposure
  4. D The raceway sizing complies with 300.17
Show answer & explanation

Correct: A — The cable is selected in accordance with Table 722.135(B)

722.3(C) permits cables selected in accordance with Table 722.135(B) to be installed in plenums and other environmental air spaces. Instrumentation tray cable rules (335.1, per 722.3(F)) apply to a different cable type, 300.17 (722.3(A)) governs raceway fill, and 300.7(A) (722.3(G)) governs temperature exposure — none of these address the plenum permission.

Vertical support, co-installation, and environmental protection for power-limited cables

NEC 722.3(H)

Article 722 sets no separate numbers for vertical support, sharing raceways with other systems, or wet/corrosive locations — it just extends the existing Chapter 3 rules to power-limited cables.

Q6 NEC 722.3(H)

A circuit integrity (CI) cable is installed in a vertical raceway running up a stairwell shaft. Which rule governs how it must be supported?

  1. A A dedicated Article 722 support-spacing table separate from other wiring methods
  2. B No support is required because CI cable is inherently self-supporting
  3. C The same general vertical-raceway conductor support requirement that applies to any wiring method
  4. D Support is required only at the very top of the raceway
Show answer & explanation

Correct: C — The same general vertical-raceway conductor support requirement that applies to any wiring method

722.3(H) requires vertical installations of CI cable in a raceway, and of fire-resistive cable or electrical circuit protective systems, to follow the general vertical support requirement used for any wiring method — Article 722 doesn't create its own separate spacing rule, and 'no support needed' or 'top only' both misstate that general requirement.

PLTC cable exceptions: industrial establishments and hoistways

NEC 722.135(C)

PLTC can run exposed in qualified-only industrial plants if it's PLTC-ER or metal-armored and supported every 6 ft, but in hoistways it must go in raceway, not exposed.

Q7 NEC 722.135(C)

In an industrial establishment with qualified maintenance and supervision, which condition permits standard Type PLTC cable (not PLTC-ER) to be installed exposed?

  1. A The cable has a metallic sheath or armor per 722.179(A)(6)
  2. B The cable is installed above 2.1 m (7 ft) from the floor
  3. C The cable run is shorter than 1.8 m (6 ft) total
  4. D The cable is labeled for cable tray use only
Show answer & explanation

Correct: A — The cable has a metallic sheath or armor per 722.179(A)(6)

Per 722.135(C)(2), Type PLTC cable with a metallic sheath or armor meeting 722.179(A)(6) may be installed exposed, with mechanical protection and support at intervals not exceeding 1.8 m (6 ft). A short run length or mounting height isn't the qualifying factor, and tray-only labeling doesn't authorize exposed use — that's what the PLTC-ER or armored path is for.

Which article's Part governs each power-limited cable type

NEC 722.3(O)

722.3(O) is the master lookup: Class 2/3 cables go to Article 725 Part II, Class 4 to Article 726 Part IV, fire alarm to Article 760 Part III, and optical fiber to Article 770 Part V.

Q8 NEC 722.3(O)

Why does Section 722.3(O) exist within Article 722?

  1. A It supersedes Articles 725, 726, 760, and 770 with one unified set of installation rules
  2. B It lists the ampacity tables for all power-limited cables
  3. C It cross-references each power-limited cable type to the Part of the article that actually governs its installation
  4. D It applies only to cables installed in hazardous locations
Show answer & explanation

Correct: C — It cross-references each power-limited cable type to the Part of the article that actually governs its installation

722.3(O) is a pointer section: Article 722 sets general rules, but 722.3(O) sends the reader to Part II of 725, Part IV of 726, Part III of 760, or Part V of 770 depending on cable type — it doesn't replace or supersede those articles.

Cables must be listed and marked per fire-resistance criteria

NEC 722.179

Cables used as wiring methods inside buildings must be listed for fire-spread resistance and marked accordingly, with optical fiber cable meeting 770.48 as the one listing exception.

Q9 NEC 722.179 Code lookup

A contractor is installing Class 2 low-voltage cable through a return-air plenum ceiling space and needs to confirm the listing requirements specific to plenum-rated cable. Which section covers this?

  1. A 722.179(A)(11)
  2. B 722.179(A)(3)
  3. C 722.179(A)(2)
  4. D 722.179(A)(1)
Show answer & explanation

Correct: D — 722.179(A)(1)

722.179(A)(1) is titled Plenum Cable and governs listing requirements for cable installed in plenum spaces. 722.179(A)(2) covers Riser Cable and 722.179(A)(3) covers General-Purpose Cable, neither of which addresses plenum installations, and 722.179(A)(11) addresses Wet Locations, not air-handling spaces.

Required durable surface markings on cables (size, type, manufacturer, temp)

NEC 722.179(B)

Cable markings repeat on a set interval — AWG size every 24 in., everything else every 40 in. — and voltage ratings are left off unless the cable carries multiple listings.

Q10 NEC 722.179(B)

Per 722.179(B), at what maximum interval must the AWG size or circular mil area be repeated on a cable's surface marking?

  1. A 1.5 m (60 in.)
  2. B 1.0 m (40 in.)
  3. C 610 mm (24 in.)
  4. D 305 mm (12 in.)
Show answer & explanation

Correct: C — 610 mm (24 in.)

722.179(B)(1) requires the AWG size or circular mil area to repeat at intervals not exceeding 610 mm (24 in.). The 1.0 m (40 in.) interval applies to all other required markings under 722.179(B)(2), not the size marking, so it's the closest wrong-rule mix-up.

Class 4 fault-managed power cable construction requirements

NEC 722.179(A)(16)

Class 4 cable must be at least 24 AWG, rated 450V dc and 60°C minimum, and must otherwise follow its own listing.

Q11 NEC 722.179(A)(16)

Per 722.179(A)(16), what is the minimum conductor size permitted in a Class 4 fault-managed power cable?

  1. A 16 AWG
  2. B 18 AWG
  3. C 24 AWG
  4. D 12 AWG
Show answer & explanation

Correct: C — 24 AWG

722.179(A)(16)(1) permits conductors not smaller than 24 AWG. The 18 AWG, 16 AWG, and 12 AWG options are all larger than required and reflect sizes more familiar from other Class 2/3 or power-circuit contexts, not the Class 4 minimum.

Removing or tagging abandoned cables

NEC 722.25

Accessible abandoned power-limited cable must be removed unless it's tagged for future use with a tag durable enough for the environment.

Q12 NEC 722.25 Code lookup

During a remodel, an electrician disconnects several communications cables in an accessible ceiling space but a few are being kept for a planned future tenant fit-out. Which section governs whether these unused cables must be removed or may instead be tagged for future use?

  1. A 722.12
  2. B 722.3(C)
  3. C 722.24(B)
  4. D 722.25
Show answer & explanation

Correct: D — 722.25

722.25 (Abandoned Cables) directly addresses removal of accessible abandoned cable or tagging it for future use with a durable tag. 722.24(B) only covers support of cables that remain in service, and 722.3(C) covers routing cables through air-handling spaces, neither of which addresses abandoned cable disposition.

4-pair power/data bundling and circuits extending beyond one building

NEC 722.135(I)

PoE-style 4-pair power/data cables borrow their bundling rule from 725.144, and any circuit conductors leaving a building toward another one on the same premises trigger extra protection rules based on conductor type.

Q13 NEC 722.135(I)

A 4-pair cable is installed to deliver both power and data to a powered device (a PoE-style application). Which section governs the bundling/ampacity adjustment for these conductors?

  1. A 820.44, the coaxial conductor installation rule
  2. B 725.144
  3. C The cable substitution table in 800.113
  4. D The general conductor bundling adjustment factors of 310.15(C)(1)
Show answer & explanation

Correct: B — 725.144

722.135(H) states that where 4-pair cables transmit power and data to a powered device, 725.144 applies. The general bundling table in 310.15(C)(1) covers ordinary power conductors, not these communications-style cables, and the cable-substitution and coaxial rules address different concerns entirely.

Listing requirement and permitted cable types by building space

NEC 722.135(B)

Every cable installed in a building must be listed, and Table 722.135(B) decides which cable types are allowed in which spaces.

Q14 NEC 722.135(B) Code lookup

A designer is specifying communications and Class 2/PLTC cables to be installed throughout a new office building — some runs in plenum ceilings, some in risers, and some in general-purpose spaces. Which section must be consulted to determine which listed cable types are permitted in each type of building space?

  1. A 722.135(C)
  2. B 722.135(B)
  3. C 722.179(A)(1)
  4. D 722.135(A)
Show answer & explanation

Correct: B — 722.135(B)

722.135(B) directs installers to Table 722.135(B), which sets out the permitted (and substitute) cable types for each building space — plenum, riser, general-purpose, etc. 722.135(A) only requires that cables be listed, without addressing which type belongs where, and 722.179(A)(1) merely defines what makes a cable plenum-rated rather than where it may be used.

Cable routing assemblies and communications raceways for power-limited cable

NEC 722.3(K)

Article 722 doesn't set its own listing or install rules for these pathways — it points straight to Article 800's cable-selection tables and installation sections, and to Article 362 for communications raceway installation.

Q15 NEC 722.3(K)

An electrician is installing a communications raceway carrying power-limited cable. Which set of installation requirements applies?

  1. A The general wiring methods requirements of Article 300 only
  2. B The requirements applicable to electrical nonmetallic tubing (ENT), per 362.24 through 362.56
  3. C The requirements applicable to cable routing assemblies, per 800.110
  4. D The requirements applicable to rigid metal conduit, per Article 344
Show answer & explanation

Correct: B — The requirements applicable to electrical nonmetallic tubing (ENT), per 362.24 through 362.56

Per 722.3(L), communications raceways are installed in accordance with 800.113 and 362.24 through 362.56, where the requirements applicable to electrical nonmetallic tubing (ENT) apply. Rigid metal conduit rules, generic Article 300 rules, and the cable routing assembly install path in 800.110 are different pathways governed by different subsections.

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