Master Conductor Area Table
The National Electrical Code lists specific cross-sectional areas, such as NEC conductor area table, for every insulation type. This table serves as your master reference for accurate conduit fill calculations.
THHN/THWN-2 Conductor Areas
Based on NEC Chapter 9 Table 5
| Size (AWG/kcmil) | Approx. Area (in²) | Diameter (in) |
|---|---|---|
| 14 AWG | 0.0097 | 0.111 |
| 12 AWG | 0.0133 | 0.130 |
| 10 AWG | 0.0211 | 0.164 |
| 8 AWG | 0.0366 | 0.216 |
The XHHW Difference
XHHW (Cross-Linked Polyethylene) insulation is often thicker than THHN (Nylon-jacketed), especially in larger wire sizes, affecting conductor area in square inches. This increased wall thickness reduces the total number of conductors allowable in the same conduit.
Thicker Polyethylene
Provides superior moisture resistance, similar to XHHW vs THHN area comparison, but reduced fill count.
Grounding Conductor Sizing
Bare copper ground wire area has a larger footprint than insulated wires.
Bare Ground
Use NEC Table 8 for conductor area (bare copper, using the area in square inches as specified in the table).
Insulated Ground
Must be treated as a standard THHN wire from the NEC Chapter 9 Table 5 for conduit sizing.
Compact Strand Advantage
Compact strand conductors (NEC Chapter 9 Table 5) are compressed to eliminate air gaps between strands, resulting in a reduced overall diameter while maintaining the same ampacity.
Strand Configuration
Are you using standard or compact stranding? This affects the diameter and your total THHN wire dimensions chart fill ratio calculation.
AWG to mm²
Standard metric conversion: #12 AWG is approximately 3.31mm², which is equivalent to a conductor area in square inches, as per NEC Chapter 9 Table 5, using an AWG to square inches conversion Sectional Area (in²) of the jacketed wire.