Electrical Reference
Wire Gauge & Ampacity Charts
AWG conductor sizing, ampacity ratings, and insulation types based on NEC 2023. Values shown are for copper conductors unless noted. Always verify with NEC Table 310.12 and local amendments.
⚠ Important — Ampacity values depend on conduit fill, ambient temperature, insulation type, bundling, and installation method. Values shown are general reference only and do not account for derating factors. Always calculate final ampacity per NEC Article 310 and verify with a licensed electrician or your local AHJ. This is not electrical advice.
AWG Ampacity Table — Copper Conductors
| AWG | Diameter (in) | Area (cmil) | Resistance (Ω/kft) | Max Amps (chassis) | Max Amps (power trans.) | Common Uses |
|---|---|---|---|---|---|---|
| AWG 14 | 0.0641" | 4,110 | 2.525 | 32A | 11A | General household wiring, 15A circuits, lighting |
| AWG 12 | 0.0808" | 6,530 | 1.588 | 41A | 16A | 20A circuits, kitchen outlets, bathrooms, GFCI circuits |
| AWG 10 | 0.1019" | 10,380 | 0.9989 | 55A | 22A | Dryers, water heaters, AC units (30A circuits) |
| AWG 8 | 0.1285" | 16,510 | 0.6282 | 73A | 32A | Electric ranges, large AC units, subpanels (40A-50A) |
| AWG 6 | 0.162" | 26,250 | 0.3951 | 101A | 47A | Subpanels, EV chargers, large appliances (55A-60A) |
| AWG 4 | 0.2043" | 41,740 | 0.2485 | 135A | 67A | Service entrance, large subpanels (70A-85A) |
| AWG 2 | 0.2576" | 66,360 | 0.1563 | 181A | 95A | Service entrance conductors, large feeders (95A-100A) |
| AWG 1/0 | 0.3249" | 105,600 | 0.09827 | 245A | 150A | Main service entrance, large feeders (125A-150A) |
| AWG 2/0 | 0.3648" | 133,100 | 0.07793 | 283A | 175A | Main service entrance (150A-175A) |
| AWG 3/0 | 0.4096" | 167,800 | 0.0618 | 328A | 200A | Main service entrance (200A residential) |
| AWG 4/0 | 0.46" | 211,600 | 0.04901 | 380A | 230A | Large commercial service, main feeders (230A+) |
Remember: Bigger AWG = Thinner Wire
AWG (American Wire Gauge) is counterintuitive. A lower gauge number means a thicker, higher-capacity wire. 10 AWG is thicker than 14 AWG.
Aluminum vs. Copper
Aluminum conductors require approximately 1 AWG size larger for equivalent ampacity. Use only AL-rated connectors and terminals. Anti-oxidant compound required.
Derating Rules (NEC 310.15)
More than 3 current-carrying conductors in a raceway requires derating. At 4-6 conductors: 80%. At 7-9: 70%. At 10-20: 50%. Always apply derating before selecting wire size.
Common Insulation Types
| Type | Temp Rating | Voltage | Typical Use |
|---|---|---|---|
| THHN/THWN | 90°C dry / 75°C wet | 600V | Most common building wire; conduit applications, dry/wet locations |
| NM-B (Romex) | 90°C (60°C in conduit) | 600V | Residential interior wiring; NOT for conduit, wet, or outdoor use |
| UF-B | 60°C | 600V | Underground feeder; direct burial, outdoor, wet locations |
| XHHW-2 | 90°C dry and wet | 600V | High heat and moisture resistance; commercial/industrial |
| USE-2/RHH/RHW-2 | 90°C | 600V | Solar PV wiring, underground service entrance |
Sources: NEC 2023 Table 310.12 · NEC Article 310 · NFPA 70 Data reviewed Q1 2026 — verify with current NEC edition and local AHJ