New AC condenser hookup
What's wrong here?
- NM cable is run inside the outdoor PVC conduit feeding the disconnect
- Schedule 40 PVC may not be used exposed outdoors; Schedule 80 is required
- Liquidtight flexible nonmetallic conduit may not be used for the condenser whip
- Nothing. This installation is compliant
Show the answer and the code reference
The answer
The installer ran NM cable through the outdoor PVC conduit to the disconnect; the inside of that conduit is a wet location and NM is not permitted there.
Correct choice: 1. NM cable is run inside the outdoor PVC conduit feeding the disconnect
Where a raceway is installed in a wet location above grade, its interior is considered a wet location, and the conductors or cables in it must be listed for wet locations (300.9, 310.10(C)). NM cable is not permitted in wet or damp locations (334.12(B)(4)); its paper separator and unrated jacket wick and hold condensation, and every summer of sweating conduit degrades the insulation. Sleeving NM in conduit outdoors is one of the most common inspection failures on AC and heat-pump hookups. The conduit itself, the LFNC whip, and the disconnect location are all fine.
How to fix it
Terminate the NM in a junction box inside the dry building and pull individual THWN-2 conductors (with an equipment grounding conductor) through the PVC to the disconnect, or replace the outdoor portion with a cable listed for wet locations such as UF.
Code references
NEC 2023 334.12(B)(4) — Uses Not Permitted
Types NM and NMS cables shall not be used in wet or damp locations.
Drills citing 334.12(B)(4)NEC 2023 300.9 — Raceways in Wet Locations Abovegrade
Where raceways are installed in wet locations abovegrade, the interior of these raceways shall be considered to be a wet location. Insulated conductors and cables installed in them shall comply with 310.10(C).
Drills citing 300.9NEC 2023 310.10(C) — Wet Locations
Insulated conductors and cables used in wet locations shall be moisture-impervious metal-sheathed, of a type listed in Table 310.4(1) for wet locations (for example THWN-2 or XHHW-2), or of a type listed for use in wet locations.
Drills citing 310.10(C)
2026 NEC:same rule and number. No 2026 change was found to the ban on NM in wet or damp locations. The supporting rule 300.9 (raceways in wet locations above grade) probably moved when Article 300 was reorganized: search results suggest 2026 300.9 now covers raceways exposed to different temperatures, and one points to 300.38 for wet locations. That new number is unconfirmed. Confidence: low
Minnesota
Minnesota adopts the NEC by reference without amendment (Minn. Rules 1315.0200; Minn. 326B.35), so 334.12(B)(4) applies as published. The 2023 NEC governs permits filed July 1, 2023 through Aug. 16, 2026; the 2026 NEC governs permits filed on or after Aug. 17, 2026 (exams moved to the 2026 NEC on Sept. 8, 2026). See the 2026 NEC note on this drill. Some states have added a short-raceway exception to 300.9 (North Carolina, for example); Minnesota has not, so the base NEC rule applies.
How Minnesota adopts the NECWhy the other choices are wrong
- Schedule 40 PVC may not be used exposed outdoors; Schedule 80 is required. Schedule 40 PVC is permitted for exposed work (352.10); only PVC exposed to physical damage must be identified for that use, such as Schedule 80.
- Liquidtight flexible nonmetallic conduit may not be used for the condenser whip. LFNC is permitted outdoors and for connections to equipment like a condenser (356.10); it is the standard whip.
- Nothing. This installation is compliant. The interior of an above-grade outdoor raceway is a wet location (300.9), and NM is not permitted in wet or damp locations (334.12(B)(4)).