Side-by-Side Comparison
Electrical & Wiring
AWG Wire Sizes vs. Wire Ampacity Ratings
Comparing 2 standards across 20 specifications. 20 key differences identified.
Comparing:
AWG Wire Sizes
Wire Ampacity Ratings
The American Wire Gauge (AWG / ASTM B258) system standardizes solid round electrical conductor diameters based on a logarithmic ratio where 36 AWG equals 0.0050 inches (0.127 mm) and 4/0 (0000) AWG equals 0.4600 inches (11.684 mm) across 39 stepping steps.
National Electrical Code (NEC) Table 310.16 establishes allowable conductor ampacities based on conductor material (Copper vs Aluminum), ambient temperature, and insulation thermal ratings (60°C TW/NM-B Romex, 75°C THWN, 90°C THHN).
Specification Comparison Table
20 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Standards
|
ASTM B258 / National Electrical Code (NEC) Chapter 9 Table 8 | — |
|
Geometric Stepping Ratio
|
Ratio between consecutive gauges is 39√(0.4600 / 0.0050) ≈ 1.1229322 | — |
|
Area Doubling Rule of Thumb
|
Decreasing by 3 gauge numbers doubles conductor cross-sectional area and halves resistance | — |
|
Diameter Doubling Rule
|
Decreasing by 6 gauge numbers doubles conductor diameter | — |
|
14 AWG (15A Residential Lighting)
|
Dia: 1.628 mm (0.0641 in) | Area: 2.08 mm² (4,110 cmil) | 8.286 Ω/km | — |
|
12 AWG (20A Small Appliance)
|
Dia: 2.053 mm (0.0808 in) | Area: 3.31 mm² (6,530 cmil) | 5.211 Ω/km | — |
|
10 AWG (30A Water Heater / Dryer)
|
Dia: 2.588 mm (0.1019 in) | Area: 5.26 mm² (10,380 cmil) | 3.277 Ω/km | — |
|
8 AWG (40-50A Electric Range)
|
Dia: 3.264 mm (0.1285 in) | Area: 8.37 mm² (16,510 cmil) | 2.061 Ω/km | — |
|
6 AWG (55-65A Subpanel / Cooktop)
|
Dia: 4.115 mm (0.1620 in) | Area: 13.30 mm² (26,240 cmil) | 1.296 Ω/km | — |
|
4/0 AWG (200A Residential Service)
|
Dia: 11.684 mm (0.4600 in) | Area: 107.2 mm² (211,600 cmil) | 0.1608 Ω/km | — |
|
Governing Code
|
— | NFPA 70: National Electrical Code (NEC) Table 310.16 |
|
Small Conductor Overcurrent Rule (NEC 240.4D)
|
— | 14 AWG Cu: Max 15A | 12 AWG Cu: Max 20A | 10 AWG Cu: Max 30A |
|
14 AWG Copper (NM-B / Romex)
|
— | 15 Amps (60°C column applied per NEC 334.80) |
|
12 AWG Copper (NM-B / Romex)
|
— | 20 Amps (Standard residential branch circuit) |
|
10 AWG Copper (NM-B / Romex)
|
— | 30 Amps (Clothes dryers, 30A water heaters) |
|
8 AWG Copper (75°C THWN / NM-B)
|
— | 40A (NM-B 60°C) / 50A (THWN 75°C conduit) |
|
6 AWG Copper (75°C THWN / NM-B)
|
— | 55A (NM-B 60°C) / 65A (THWN 75°C conduit) |
|
4 AWG Copper (75°C THWN)
|
— | 85 Amps (Residential subpanel feeder) |
|
2 AWG Copper (75°C THWN)
|
— | 115 Amps (100A subpanel / main feeder) |
|
4/0 Aluminum (75°C XHHW / SE)
|
— | 180 Amps under standard NEC Table 310.16 ampacity; commonly used as the minimum conductor for a 200A dwelling service under NEC's separate service-conductor allowance (Table 310.12, formerly 310.15(B)(7)) |