Spot the Violation

ElectricalAppliances, HVAC, pools & specialLevel 32023 NEC

Condenser disconnect, cover open

Close-up of a gray outdoor air-conditioner disconnect on the painted concrete-block wall of a small office building, with its cover swung open. The pull-out block holds two 30 A cartridge fuses. Black and red 12 AWG THWN-2 conductors and a green grounding conductor enter from PVC conduit at the bottom left; another black, red and green set leaves through liquidtight conduit at the bottom right toward the corner of a condenser at the right edge. The condenser nameplate reads: 208/230 V, 1 phase, compressor RLA 13.4, fan FLA 0.8, minimum circuit ampacity 17.6, maximum fuse or HACR breaker 30 A. The enclosure label reads 60 A, 240 VAC, Type 3R. Light snow covers the ground. SPLIT SYSTEM CONDENSING UNIT VOLTS 208/230 PH 1 HZ 60 COMPRESSOR RLA 13.4 LRA 64 FAN MOTOR FLA 0.8 HP 1/6 MIN. CIRCUIT AMPACITY 17.6 MAX. FUSE OR HACR BKR 30 A USE COPPER CONDUCTORS ONLY 60 A240 VACTYPE 3RFUSIBLE 30A30A 250V250V TDTD 12 AWG CU THHN/THWN-2 12 AWG CU THHN/THWN-2
Condensing unit disconnect behind a small office building, early winter

What's wrong here?

  1. Nothing. This installation is compliant
  2. 12 AWG copper conductors may not be protected by 30 A fuses
  3. The fuses must not exceed the 17.6 A minimum circuit ampacity
  4. A fused disconnect cannot be used where the nameplate calls for an HACR breaker
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Show the answer and the code reference

The answer

Nothing is wrong: 12 AWG conductors on 30 A fuses are correct for this condenser because its nameplate lists a 17.6 A minimum circuit ampacity and a 30 A maximum fuse.

Correct choice: 1. Nothing. This installation is compliant

Air-conditioning circuits are an exception to the small-conductor rule: 240.4(G) points to Article 440. There, conductors only have to meet the nameplate minimum circuit ampacity (440.35, marked per 440.4(B); here 125% of the 13.4 A RLA plus the 0.8 A fan, as in 440.33), and the overcurrent device may go up to the nameplate maximum so the compressor can start (440.22). 12 AWG copper (25 A at 75 C) exceeds the 17.6 A MCA, and the 30 A fuses do not exceed the 30 A maximum fuse on the nameplate. The disconnect is within sight, readily accessible with clear working space in front, Type 3R, not mounted on a service panel of the unit (440.14), and rated above the load (440.12). This is not a dwelling, so the 210.8(F) outdoor-outlet GFCI rule does not apply, and 210.8(B) covers only receptacles.

How to fix it

No correction needed. Confirm the fuses are a type the nameplate allows, and that the 210.63(A) service receptacle is within 25 ft on the same level.

Code references

  • NEC 2023 240.4(G) — Overcurrent Protection for Specific Conductor Applications

    Conductors for specific applications listed in Table 240.4(G), including air-conditioning and refrigeration equipment circuit conductors, are protected per the referenced articles (Article 440, Parts III and VI) instead of the small-conductor limits of 240.4(D).

    Drills citing 240.4(G)

  • NEC 2023 440.22(C) — Protective Device Rating Not to Exceed the Manufacturer's Values

    Where the maximum protective device rating marked by the manufacturer is less than the value calculated under 440.22(A) or (B), the protective device must not exceed the manufacturer's marked value.

    Drills citing 440.22(C)

  • NEC 2023 440.35 — Multimotor and Combination-Load Equipment

    The ampacity of the conductors supplying multimotor and combination-load equipment must not be less than the minimum circuit ampacity marked on the equipment in accordance with 440.4(B).

    Drills citing 440.35

  • NEC 2023 440.14 — Location

    The disconnecting means must be within sight from and readily accessible from the air-conditioning or refrigerating equipment, must meet the working space requirements of 110.26(A), and must not be on panels designed to allow access to the equipment.

    Drills citing 440.14

2026 NEC:same rule and number. No 2026 change to 240.4(G) or Table 240.4(G), or to the Article 440 MCA/maximum-overcurrent rules (440.22, 440.35), was found; the 2026 conductor changes seen (16 AWG added in 310) do not touch this rule. Search snippets only. Confidence: low

Minnesota

MN adopts the NEC rule as writtenConfidence: high

Minnesota adopts the NEC without section amendments. The 2023 NEC applies to permits filed July 1, 2023 through Aug. 16, 2026, and the 2026 NEC to permits filed on or after Aug. 17, 2026 (Minn. Stat. 326B.35; Minn. Rules 1315.0200; DLI electrical codes and standards page). No Minnesota change to 240.4(G) or Article 440 is known.

How Minnesota adopts the NEC

Why the other choices are wrong

  • 12 AWG copper conductors may not be protected by 30 A fuses. 240.4(D) does not govern here: 240.4(G) sends air-conditioning circuits to Article 440. 12 AWG exceeds the 17.6 A MCA, and 30 A matches the nameplate maximum fuse.
  • The fuses must not exceed the 17.6 A minimum circuit ampacity. MCA sizes the conductors; the nameplate maximum fuse or HACR breaker (here 30 A) sets the overcurrent limit (440.22(C)). Undersized fuses just blow on compressor start.
  • A fused disconnect cannot be used where the nameplate calls for an HACR breaker. The nameplate says 'max fuse or HACR breaker'; either a fuse or an HACR-rated breaker is acceptable up to 30 A.
Code complianceLevel 3 · Master#hvac#air-conditioner#disconnect#fuses#mca#mocp#calibration

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