Side-by-Side Comparison
Electrical & Wiring
AWG Wire Sizes vs. Electrical Conduit Fill Capacity
Comparing 2 standards across 17 specifications. 17 key differences identified.
Comparing:
AWG Wire Sizes
Electrical Conduit Fill Capacity
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.
Electrical conduit fill capacity is strictly regulated under the National Electrical Code (NEC Chapter 9, Tables 1, 4, and 5) limiting total conductor cross-sectional area to 40% of internal conduit area for three or more wires, preventing heat buildup and insulation damage during wire pulls.
Specification Comparison Table
17 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Standards
|
ASTM B258 / National Electrical Code (NEC) Chapter 9 Table 8 | NFPA 70 (NEC) Chapter 9 / Annex C (Conduit Fill Tables) / NEMA Standards |
|
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 | — |
|
The NEC 40% Fill Rule
|
— | 1 Conductor: 53% max | 2 Conductors: 31% max | 3 or More Conductors: 40% max cross-sectional fill |
|
1/2" EMT Conduit (Trade Size 16)
|
— | Internal Area: 0.304 sq in | 40% Fill: 0.122 sq in | Max 9× 14 AWG, 6× 12 AWG, or 4× 10 AWG THHN wires |
|
3/4" EMT Conduit (Trade Size 21)
|
— | Internal Area: 0.533 sq in | 40% Fill: 0.213 sq in | Max 16× 14 AWG, 10× 12 AWG, or 7× 10 AWG THHN wires |
|
1" EMT Conduit (Trade Size 27)
|
— | Internal Area: 0.864 sq in | 40% Fill: 0.346 sq in | Max 26× 14 AWG, 16× 12 AWG, or 12× 10 AWG THHN wires |
|
1-1/4" EMT Conduit
|
— | Internal Area: 1.496 sq in | 40% Fill: 0.598 sq in | Ideal for 100A subpanel feeds (3× 1 AWG + 6 AWG ground) |
|
2" EMT Conduit
|
— | Internal Area: 3.356 sq in | 40% Fill: 1.342 sq in | Standard 200A residential service mast (3× 2/0 Cu or 4/0 Al) |
|
Conduit Types
|
— | EMT (Electrical Metallic Tubing), Schedule 40 PVC, Schedule 80 PVC (Thick wall), Rigid Metal (RMC) |