Wiring Methods and Materials practice questions (Articles 348–356)

Correct: C — The openings must be spaced not greater than 1.4 m (4½ ft) apart

Per 348.30(B), horizontal FMC runs supported by openings through framing members at intervals not greater than 1.4 m (4½ ft) are permitted, provided the FMC is still securely fastened within 300 mm (12 in.) of termination points. The 900 mm figure is a flexibility-tail length from 348.30(A), not the framing-opening interval, and framing openings do qualify as support so a separate strap every 12 in. is not required.

Correct: C — 360 degrees

348.24(B) limits the total degrees of bends in a conduit run to 360 degrees between pull points, the same cumulative-bend limit used for other raceway types. 270 and 180 degrees are lower thresholds sometimes confused with other installation limits, and there is in fact a hard numeric cap, not a pull-test standard.

Correct: D — A separate equipment grounding conductor must be installed

Per 348.60(B), where flexibility is necessary after installation (such as to allow equipment movement), an equipment grounding conductor must be installed — the FMC itself cannot be relied on as the ground path. Using the FMC jacket alone applies only to fixed installations under 250.118(A)(5). The 6 ft references describe the separate bonding jumper length allowance elsewhere in Article 250, not an exception to this requirement.

Correct: B — 348.12

348.12(6) specifically prohibits FMC underground or embedded in poured concrete or aggregate. 348.10 lists where FMC IS permitted (the mirror-image section), and 348.42/348.30 cover couplings/connectors and securing/supporting, not permitted uses.

Correct: D — Percentage fill from Table 1, Chapter 9

348.22 requires standard trade sizes of FMC to use the percentage fill in Table 1, Chapter 9. Only metric designator 12 (trade size 3/8) uses the fixed count in Table 348.22. The nipple fill rule and ampacity adjustment tables address different questions entirely.

Correct: D — 348.20(A)

348.20(A) lists the five permitted exceptions (including motor lead enclosures per 430.245(B)) allowing FMC smaller than metric designator 16. 348.20(B) instead sets the maximum size limit, and 348.12/348.22 don't address minimum trade size at all.

Correct: A — 1.4 m (4½ ft)

Per 350.30(A), LFMC must be supported and secured at intervals not exceeding 1.4 m (4½ ft). The 900 mm figure is the flexibility-exception limit for smaller trade sizes, 1.8 m applies to luminaire taps and accessible-ceiling connections, and 300 mm is the fastening distance from terminations, not the support interval.

Correct: D — A separate equipment grounding conductor must be installed

Per 350.60(B), where flexibility is necessary to minimize vibration transmission or allow equipment movement after installation, an equipment grounding conductor shall be installed. Relying on the LFMC jacket alone is only permitted for fixed installations under 350.60(A), and the 6 ft length rule relates to flexible connection permissions elsewhere, not to omitting the EGC here.

Correct: B — Trade size 1/2

350.20(A) sets the general minimum at metric designator 16 (trade size 1/2). Trade size 3/8 is smaller and only permitted under the limited conditions referenced in 348.20(A), not as the default minimum.

Correct: B — 360 degrees

Per 350.24(B), the total degrees of bends in a conduit run cannot exceed 360 degrees between pull points. The other values are not recognized thresholds under this section.

Correct: C — 350.22(A)

350.22(A) covers metric designators 16 through 103 (trade sizes 1/2 through 4) and directs fill to Table 1, Chapter 9. 350.22(B) only applies to the smaller 3/8 in. (metric designator 12) size, which uses Table 348.22 instead; 350.20(B) sets maximum trade size, not fill.

Correct: D — No, angle connectors are not permitted to be concealed

Per 350.42, angle connectors shall not be concealed, regardless of whether the fitting is listed for LFMC. Being listed for LFMC is a separate requirement and doesn't override the concealment prohibition. Direct-burial marking applies to straight fittings for earth burial, not to concealment in a wall. LFMC fittings in general are not banned from wall cavities — only angle connectors are restricted from being concealed.

Correct: A — Splicing devices only, as permitted by 110.14(B) and 314.16(C)(2)

352.10(I) permits a PVC-supported conduit body to contain only splicing devices allowed by 110.14(B) and 314.16(C)(2). A snap switch or dimmer isn't a splicing device, and being rated for the trade size doesn't override that restriction.

Correct: B — Whenever the calculated thermal length change is 6 mm (1/4 in.) or greater

352.44(A) sets the trigger as expected length change of 6 mm (1/4 in.) or greater between securely mounted terminations, based on Table 352.44(A) — not sunlight exposure, a fixed run length, or trade size.

Correct: C — At least every 3 m (10 ft)

352.120 requires marking at least every 3 m (10 ft), consistent with 110.21(A). The 5 ft, 20 ft, and once-per-length options don't match the stated interval.

Correct: B — Resistance to sunlight effects

352.100 lists flame retardance plus resistance to impact/crushing, heat distortion, low temperature, and sunlight as aboveground-specific requirements. Sunlight resistance only appears in the aboveground list. Moisture resistance applies to both, impact/crushing strength is required underground too (for handling and installation abuse), and corrosive-agent resistance is an underground-specific requirement, not an aboveground one.

Correct: C — The PVC material must be specifically approved for the chemicals present

352.10(C) permits PVC in severely corrosive locations per 300.6, but only where the material is specifically approved for the chemicals involved — not just any PVC, and it isn't blanket-prohibited or blanket-approved.

Correct: B — 352.12(A)

352.12(A) prohibits PVC conduit in hazardous (classified) locations except as permitted elsewhere in the Code. 352.12(D) governs excessive ambient heat and 352.12(E) governs theaters — neither addresses classified locations, and 352.10(C) only covers corrosive influences for permitted uses.

Correct: B — 180 degrees

Section 352.24(B) caps total bends at 360 degrees between pull points. Two 90-degree bends already used 180 degrees, leaving 180 degrees before another pull point is needed. 90 degrees and 270 degrees misjudge the remaining allowance, and bending is still permitted since the 360-degree cap hasn't been reached.

Correct: C — 352.46

352.46 is the section requiring a bushing or adapter at any box, fitting, or enclosure entry unless the enclosure's design already gives equivalent protection. 352.48 (Joints) covers joining conduit lengths, 352.28 (Trimming) covers deburring cut ends, and 352.24 (Bends) governs how bends are made and how many are allowed per run — none of these address protecting conductors at an enclosure entry.

Correct: C — 352.10(J)

352.10(J) is the specific rule allowing higher-temperature-rated conductors in PVC as long as actual operating temperature doesn't exceed the conduit's listed rating. 352.12(D) addresses ambient temperature limits for where PVC itself may be used (an installation-location restriction), not the conductor-vs-conduit operating temperature relationship, so it doesn't answer this scenario.

Correct: A — A separate equipment grounding conductor installed in the conduit

Per 352.60, because PVC conduit cannot serve as an equipment grounding path, a separate equipment grounding conductor shall be installed in the conduit where equipment grounding is required. Bonding jumpers and metallic bushings address raceway continuity for metal systems, not PVC, and 'no grounding means' is incorrect since 352.60 mandates one absent a 250.142 exception.

Correct: B — 360 degrees total between pull points

353.24(B) caps the total degrees of bend in a run at 360 degrees between pull points, not per individual bend. The 180-degree figure and the 'no limit' option are both incorrect thresholds; 360.24(B) doesn't reference lubricant as a workaround.

Correct: A — 353.22

353.22 sets conductor and cable fill by referencing Table 1, Chapter 9. 353.20(B) covers maximum trade size of the ENT itself, and 353.24(B) covers the number of bends allowed in one run — neither addresses conductor fill count.

Correct: A — Capability of withstanding continued loading likely to be encountered after installation

353.100 requires HDPE intended for direct burial without concrete encasement to withstand continued loading likely to be encountered after installation. UV resistance, a specific wall thickness, and a factory coating are not requirements stated in this section.

Correct: D — 353.60

353.60 covers grounding requirements for this raceway type, including when the equipment grounding conductor must be installed in the conduit and the exceptions tied to 250.134 and 250.142. 353.56 addresses splices and taps, not grounding, so it wouldn't be the section a student needs for this scenario.

Correct: B — 353.48

353.48 specifically addresses how joints between conduit lengths (and to couplings, fittings, and boxes) must be made, including heat fusion, electrofusion, or mechanical fittings for HDPE. 353.24(A) instead covers how bends are made, and 353.56 covers splices and taps of conductors, not conduit joints.

Correct: D — In continuous lengths shipped in a coil, reel, or carton

354.100(A) states NUCC is an assembly provided in continuous lengths shipped in a coil, reel, or carton — not pre-cut rigid sticks or a custom-built assembly. This distinguishes NUCC from rigid raceway products sold in fixed trade lengths.

Correct: A — Every 3.05 m (10 ft)

354.120 requires NUCC to be clearly and durably marked at least every 3.05 m (10 ft) as required by 110.21. Marking only at each end, or at the 6 ft or 20 ft intervals used for other purposes elsewhere in the Code, doesn't meet this spacing requirement.

Correct: B — When encased in not less than 2 in. (50 mm) of concrete

354.10(5) permits above-ground NUCC only where encased in not less than 50 mm (2 in.) of concrete. Strapping to a wall, running in free air, or sleeving in metal raceway are not the code-recognized above-ground method and would leave it exposed, which 354.12(1) prohibits.

Correct: C — No, because the run has already reached the 360-degree maximum

354.24(B) caps total bends at 360 degrees between pull points. Four 90-degree bends already total 360 degrees, so no additional bend is allowed in that run. Meeting the minimum radius from 354.24(A) is a separate requirement and doesn't override the cumulative-degree limit.

Correct: C — 354.22

354.22 sends the installer to Table 1 of Chapter 9 for percentage fill, which is the actual conductor-count limit. 354.20(B) only addresses the maximum trade size of the conduit itself, and 354.100(D) is a construction/product-standard requirement on the manufactured assembly's conductor fill, not a field fill-limit rule for conductor count.

Correct: C — Yes, because the total is 225 degrees, under the 360-degree limit

355.24(B) caps the total degrees of bend in a run at 360 degrees between pull points, regardless of how many individual bends make up that total. Here 90 + 90 + 45 = 225 degrees, which is compliant. There's no rule limiting the run to a single bend, no per-bend degree cap, and offsets are ordinary bends, not a prohibited feature.

Correct: D — No more than 900 mm (3 ft) from the box

355.30(A) requires RTRC to be securely fastened within 900 mm (3 ft) of each outlet box, junction box, device box, conduit body, or other termination, unless the conduit is listed for a different distance. The 1.5 m and 1.8 m options and skipping fastening near boxes are not permitted under the general rule.

Correct: C — RTRC is prohibited except as permitted in 501.10(B)(1)(6)

355.12(A)(2) prohibits RTRC in Class I, Division 2 locations except as permitted in 501.10(B)(1)(6) — a narrow carve-back, not a blanket allowance for any listed product. RTRC is also barred from hazardous locations generally under 355.12(A)(1), so the 'all hazardous locations, no exceptions' option and the 'only Division 1' option both misstate the rule.

Correct: D — The entire conduit system, including boxes and fittings, must be installed to keep water out, with corrosion-resistant supports and hardware

355.10(D) requires the entire conduit system — conduit, boxes, and fittings — to be installed and equipped to prevent water entry, with corrosion-resistant supports, bolts, straps, and screws. RTRC is explicitly permitted in wet locations, so ruling it out is wrong, and Type XW addresses physical damage, not wet-location sealing.

Correct: C — 355.46

355.46 requires a bushing or adapter where RTRC enters a box or enclosure unless the enclosure design already gives equivalent protection. 355.48 covers making up joints between conduit lengths, and 355.30(A) covers securing/fastening the raceway, neither of which addresses conductor abrasion at a termination.

Correct: C — The expected length change from thermal expansion, per Table 355.44, is 6 mm (1/4 in.) or greater

355.44 requires expansion fittings where the length change calculated from Table 355.44 is expected to be 6 mm (1/4 in.) or greater between securely mounted terminations. Trade size, fire-rated wall penetrations, and bend count are not the trigger described in this section.

Correct: C — A separate equipment grounding conductor must be installed in the conduit

Per 355.60, where equipment grounding is required, a separate grounding conductor must be installed in the conduit — RTRC is nonmetallic and cannot itself provide an equipment ground, unlike metal raceways. A metallic bushing doesn't change that.

Correct: B — At intervals not exceeding 3 ft, and within 12 in. of each junction box

356.30(1) requires LFNC runs over 6 ft to be securely fastened at intervals not exceeding 3 ft AND within 12 in. of every outlet box, junction box, cabinet, or fitting — both conditions apply together, not one or the other.

Correct: B — As a 6 ft or shorter tap connection to a luminaire, as part of a listed assembly

356.20(A)(2) permits trade size 3/8 LFNC only for tap connections to luminaires (per 410.117(C)) or utilization equipment, limited to 1.8 m (6 ft), as part of a listed assembly. General branch-circuit runs, feeder use, and unlimited lengths are not covered by this exception.

Correct: A — 356.10

356.10(4) permits LFNC for direct burial where it is listed and marked for that purpose. 356.42 instead covers couplings and connectors, and would only become relevant if the installer were encasing the LFNC in concrete rather than burying it directly in earth.

Correct: B — 360 degrees total

356.24(B) caps the total of all bends in one LFNC run at 360 degrees between pull points. Meeting the Table 2 bend radius is a separate requirement under 356.24(A) and doesn't remove the cumulative-degree limit, and the 180° and 270° figures aren't the code value.

Correct: C — A straight LFNC fitting listed for the raceway

356.42 permits only straight LFNC fittings for direct burial or encasement in concrete. Angle connectors, even if listed for LFNC and rated for wet locations, are not permitted for this use — that rating doesn't extend to burial or concrete encasement.

Correct: D — Install a separate equipment grounding conductor in the conduit

356.60 requires a separate equipment grounding conductor installed in the conduit whenever equipment grounding is required, because LFNC itself is not recognized as an equipment grounding path. Relying on the jacket, bonding to a ground rod, or skipping grounding entirely are not permitted substitutes.