Wiring Methods and Materials practice questions (Articles 332–344)

Correct: D — Only where another article of the Code specifically permits it

332.10(7) permits MI cable in hazardous (classified) locations only where specifically permitted by other articles of the Code — the metal sheath alone doesn't grant blanket approval, and MI cable isn't outright excluded either, so both the 'anywhere' and 'never' options misstate the rule.

Correct: A — The temperature rating of the listed end seal fitting

332.80 requires that the conductor temperature at the end seal fitting not exceed the fitting's listed temperature rating, and that terminations/equipment temperature ratings not be exceeded — this can cap ampacity below what 310.14 alone would permit. The other options aren't ampacity-limiting factors under this section.

Correct: A — 332.24

332.24 sets the inner-edge bending radius limits for MI cable based on external diameter. 332.30 and 332.30(A) instead cover securing/supporting distances and running through framing holes, not bend radius, and 332.17 addresses installation through framing members, not bending.

Correct: B — No, the end seal fitting must be installed immediately after stripping

332.40(B) requires the end seal fitting immediately after stripping, not just before energizing — the mineral insulation can absorb moisture during any delay, regardless of location. The 'seal before energizing' and 'only in damp locations' options both describe timing or conditions the section doesn't allow.

Correct: A — Stranded copper

Per 332.104, Type MI cable conductors must be solid copper, nickel, or nickel-coated copper. Stranded copper is not one of the permitted forms — the conductors are solid, matching standard AWG and kcmil resistance values.

Correct: D — It must not exceed the 60°C rated ampacity for that conductor size

334.80 permits using the 90°C column for adjustment and correction calculations, but the final calculated ampacity can never exceed the 60°C rated conductor ampacity. The 75°C option and 'equal to 90°C' option both misstate the cap.

Correct: B — Rigid metal conduit, IMC, EMT, Schedule 80 PVC, or -XW RTRC extending at least 6 in. above the floor

Per 334.15(B), cable passing through a floor must be enclosed in rigid metal conduit, IMC, EMT, Schedule 80 PVC, or -XW rated RTRC extending at least 150 mm (6 in.) above the floor. Schedule 40 PVC and a shorter 4 in. extension don't meet this requirement, and straps alone don't provide the physical damage protection this section requires.

Correct: A — No, both NM and NMC are prohibited in these commercial garages under 334.12(A)(4)

Section 334.12(A)(4) prohibits both Types NM and NMC in commercial garages having hazardous (classified) locations as defined in 511.3 — the ban applies to both cable types equally, not just NM. NMC's tougher sheath does not change this, and embedding in concrete is separately prohibited by 334.12(A)(9).

Correct: C — Type NMC, since it is permitted in damp locations

Per 334.10(B), Type NMC is permitted in dry, wet, damp, or corrosive locations. Type NM, per 334.10(A), is limited to normally dry locations, so it does not satisfy a damp location. Article 334 cables aren't dry-only as a category — NMC extends the use cases.

Correct: A — The cable is permitted to be unsupported for this run

334.30(B)(1) permits NM cable to be unsupported when it is fished between access points through concealed spaces in finished buildings and supporting is impracticable. The other options misstate the rule — supporting every 1.4 m applies to normal runs, not fished cable, and there's no raceway requirement or commercial-only limitation here.

Correct: C — 5 times

334.24 sets the minimum inner-edge bend radius at 5 times the cable diameter. The 4, 6, and 8 times multiples belong to bending-radius rules for other cable and conductor types elsewhere in the NEC, not NM/NMC.

Correct: A — It must form a close fit around the outer covering of the cable and fully enclose any stripped portion

Per 334.40(B), the device's opening must form a close fit around the cable's outer covering and fully enclose any part of the cable with covering removed, regardless of whether the installation is exposed or concealed. There is no oversize clearance allowance, and no separate box connector is required since the whole point of 334.40(B) is that no box is used.

Correct: C — Voltage rating

335.7 requires marking in accordance with 310.8(A)(2) through (A)(5), which covers items like manufacturer identification, conductor size, and type, but explicitly states that voltage ratings shall not be marked on the cable.

Correct: C — No, Type ITC cable is not permitted with power, lighting, or non-power-limited Class 1 circuits

335.5 explicitly prohibits installing Type ITC cable with power, lighting, or non-power-limited Class 1 circuits — this is a flat rule, not one that a metallic sheath, matched voltage rating, or current limit can override.

Correct: A — 14 AWG

336.104 sets 14 AWG copper (or nickel/nickel-coated copper) as the minimum for ungrounded, grounded, and equipment grounding conductors in TC cable. The 18 AWG size is the minimum only for copper control/signal conductors, and 12 AWG is the minimum for aluminum power conductors, not copper.

Correct: C — The cable must be Type TC-ER, continuously supported, and protected against physical damage

Section 336.10(7) permits Type TC cable between a cable tray and utilization equipment only when it is Type TC-ER, installed in a qualified-persons industrial establishment, continuously supported and protected from physical damage, meets MC cable crush/impact requirements, and is secured at intervals not exceeding 1.8 m (6 ft). Plain Type TC without the ER rating is not permitted for this exposed application; the messenger-wire option applies to outdoor runs, not tray-to-equipment connections.

Correct: B — 392.80(A), the cable tray ampacity provision

Per 336.80, 14 AWG and larger conductors in Type TC cable use 392.80(A) for ampacity. 402.5 only applies to 18 AWG through 16 AWG conductors in a tray, and 310.14 only applies when the cable is installed outside a cable tray.

Correct: A — 12 times

Per 336.24, Type TC cable with metallic shielding must have a minimum bending radius of not less than 12 times the cable's overall diameter. The 4x and 6x multipliers apply only to unshielded TC cable at smaller and larger diameters, and 8x is not a value given anywhere in this rule.

Correct: D — A metallic sheath or armor under or over the nonmetallic jacket

336.100 states a metallic sheath or armor is not permitted either under or over the nonmetallic jacket. Metallic shields over groups of conductors under the outer jacket are explicitly permitted, and the flame-retardant nonmetallic jacket itself is required by 336.116.

Correct: B — Table 402.5 or 310.14(B)

Per 337.80, 18 AWG and 16 AWG Type P conductors use Table 402.5 or 310.14(B), not the general 310.14(A) rule that applies to 14 AWG and larger conductors. 392.80 is only an option when the cable is installed in cable tray.

Correct: D — Under engineering supervision, with conditions of maintenance and supervision ensuring only qualified persons monitor and service the system

337.10(1) specifically requires engineering supervision and conditions of maintenance/supervision ensuring only qualified persons monitor and service the system. Raceway type, occupancy class, and feeder rating aren't the qualifying conditions this section names.

Correct: C — No, because the jacket requirement only applies when single conductors are installed external to an enclosure or industrial machinery

337.115 requires the overall nonmetallic jacket on single conductor cables only when they are installed external to an enclosure or industrial machinery. Inside the enclosure/machinery, that jacket isn't mandated. The multiconductor jacket rule (always required) is a separate provision, and armor is optional, not a jacket substitute, under 337.116.

Correct: A — They must be listed and identified for securement and support

337.30 requires cable ties used to support and secure Type P cable to be listed and identified for that specific purpose. There's no metallic/grounding requirement, no 12 in. spacing rule, and no color-matching rule stated in this section.

Correct: C — It must be used only for equipment grounding purposes

Per 338.10(B)(2), when SE cable is used as a feeder or branch circuit, the uninsulated conductor is limited to equipment grounding purposes. Using it as a grounded (neutral) conductor is only allowed in existing installations meeting 250.32, 250.140, and 225.30 through 225.40 — not in new work, and taping it doesn't change that restriction.

Correct: A — Article 334, Part II, excluding 334.80

338.10(B)(4)(a)(1) requires interior SE wiring to follow Article 334, Part II (the NM cable installation rules) but specifically excludes 334.80. Article 225 governs exterior installs, and Article 340 governs USE cable, not interior SE branch circuits.

Correct: B — No, SE cable is never permitted underground, with or without a raceway

Per 338.12(A)(2), Type SE cable is not permitted underground under any condition, whether or not it is installed in a raceway. Wet-location rating, raceway use, and burial depth are all irrelevant here — the underground prohibition is absolute.

Correct: D — 338.120

338.120 is the marking section, and it explicitly requires cable with a reduced-size neutral to be so marked. 338.10(B)(1) addresses insulation of the grounded conductor for branch-circuit/feeder use, and 338.100(B) covers uninsulated conductor construction — neither deals with marking.

Correct: B — Embedded in plaster as a nonheating lead where permitted by 424.43

340.12(8) bars UF cable embedded in poured cement, concrete, or aggregate, but specifically carves out an exception for plaster nonheating leads permitted under 424.43. Service-entrance use, commercial garages, and elevator hoistways are all separately prohibited under 340.12(1), (2), and (6).

Correct: A — 340.10

340.10(2) is the uses-permitted list item that specifically allows UF as single-conductor cables, tying the conductors back to 300.3. 340.12 only lists where UF is NOT permitted, 340.104 covers conductor material/sizing, not permitted uses, and 340.24 covers bending radius.

Correct: C — 5 times the diameter

340.24 sets the minimum inner-edge bending radius for Type UF cable at 5 times the cable diameter. 6 times is a threshold electricians may recall from other cable/raceway bending rules, and 10 times is associated with certain conductor or cable configurations elsewhere in the Code, but neither applies to Type UF under 340.24.

Correct: D — 340.104

340.104 sets the conductor size limits (14 AWG copper or 12 AWG aluminum/copper-clad aluminum through 4/0 AWG) for Type UF cable. 340.80 covers ampacity, not conductor sizing, and 340.112/340.108 address insulation and equipment grounding conductors, not the sizes of the current-carrying conductors.

Correct: B — 1.5 m (5 ft)

342.30(A)(2) allows the fastening distance near a termination to increase to 1.5 m (5 ft) when structural members do not readily permit fastening within the standard 900 mm (3 ft). 3 m (10 ft) is the general support interval under 342.30(B)(1), not the extended securing distance, which is why it's a tempting but wrong choice.

Correct: D — 360 degrees

342.24(B) caps the total bends in a conduit run at 360 degrees between pull points. 180 and 270 degrees are below the actual limit, and 720 degrees would be double what's permitted.

Correct: B — 342.42(A)

342.42(A) requires threadless couplings and connectors to be made tight, and specifically to be the concretetight type where buried in masonry or concrete. 342.10(B) addresses permitted uses in corrosion environments, not coupling tightness, and 342.46 covers bushings, not couplings.

Correct: B — Under all atmospheric conditions and occupancies

342.10(A) permits IMC under all atmospheric conditions and occupancies — there's no blanket limitation to dry, indoor, or low-damage settings. IMC is also explicitly permitted in wet locations and areas of severe physical damage per 342.10(D) and (E).

Correct: D — 342.46

342.46 requires a bushing at the conduit termination to protect wires from abrasion unless the enclosure itself is designed to provide that protection. 342.42 covers couplings and connectors (joining conduit lengths, not box entry protection), and 342.60 covers grounding, neither of which addresses abrasion protection at the entry point.

Correct: A — 342.22

342.22 sets the conductor/cable fill limit by referring to Table 1, Chapter 9. 342.24(B) covers the number of bends in one run (not conductor fill), and 342.20(B)/342.30(B) address maximum trade size and supports, not fill.

Correct: C — Stainless steel IMC with powder-coated steel boxes

342.14(3) permits steel boxes and enclosures (galvanized, painted, powder or PVC coated) with stainless steel IMC when not subject to severe corrosive influences. Plain galvanized fittings are not on the allowed list for stainless steel IMC, aluminum boxes aren't listed as permitted with stainless steel IMC, and accessories must be stainless steel, nonmetallic, or approved — not just any metallic accessory.

Correct: D — Fastening can be increased to 5 ft since structural members don't readily permit fastening within 3 ft

Under 344.30(A)(2), fastening distance can be increased to 1.5 m (5 ft) where structural members don't readily permit fastening within 900 mm (3 ft). Leaving it unfastened isn't an option, and fishing only applies to concealed work in finished buildings where securing is impracticable, not just distant framing.

Correct: C — That the environment is approved for aluminum RMC

Per 344.10(A)(2), aluminum RMC is permitted where approved for the environment — there's no blanket 'all conditions' approval like galvanized steel, stainless steel, and red brass get. Supplementary corrosion protection is only required for concrete-encased, earth-contact, or direct-burial installations under 344.10(B)(2), the 450 mm depth rule applies to cinder fill under 344.10(C), and enamel-only protection is a ferrous raceway rule under 344.10(A)(3), not an aluminum rule.

Correct: D — Yes, because 270 degrees total is within the 360-degree limit between pull points

Three 90-degree bends total 270 degrees, which is under the 360-degree maximum allowed between pull points per 344.24(B). There's no separate rule limiting the number of bends by count, only by cumulative degrees.

Correct: A — 344.42(A)

344.42(A) covers threadless couplings and connectors, including the requirement that they be made tight, be concrete-tight when buried, and comply with 314.15 in wet locations. 344.10(D) only addresses general wet-location use of RMC, not the fitting itself, so it doesn't answer a fitting-selection question.

Correct: C — 344.14

344.14 (Dissimilar Metals) specifically permits aluminum or stainless steel fittings/enclosures with galvanized steel RMC (and vice versa) where not subject to severe corrosion, and directs that dissimilar metals in contact be avoided to prevent galvanic action. 344.10(B)(2) only addresses supplementary corrosion protection for aluminum RMC itself, not mixed-metal fittings.

Correct: B — 344.46

344.46 is the specific rule requiring a bushing where RMC enters a box, fitting, or enclosure unless that enclosure is itself designed to protect the conductors. 344.28 covers reaming and threading of the conduit ends (a related but distinct step before termination), not the bushing requirement itself.

Correct: B — Red brass

344.100 lists exactly four permitted RMC materials: steel with protective coatings, aluminum, red brass, and stainless steel. Red brass is one of them. Bare uncoated steel doesn't qualify because steel RMC must carry a protective coating, and the fiberglass and composite options aren't on the list at all.