Conductor Lookup
Values from NEC 2017 (NFPA 70-2017) Chapter 9 Tables 8 and 9, exactly as printed [1]; the site’s calculators each cite the NEC edition their own data came from. Use them in the Wire/Cable Sizing & Voltage Drop calculator, and the overall diameters in the Conduit Fill calculator.
DC Properties — NEC Chapter 9 Table 8
| Size | Strands | Area | Strand diameter | Overall diameter | Overall area | Copper, uncoated | Copper, coated | Aluminum | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| mm² | cmil | mm | in. | mm | in. | mm² | in² | Ω/km | Ω/kft | Ω/km | Ω/kft | Ω/km | Ω/kft | ||
DC resistance at 75 °C (167 °F); Class B stranding, with the overall diameter of the circle around the strands. The kcmil sizes leave the cmil column blank because the size is the area. For 1500–2000 kcmil the printed coated-copper Ω/km values repeat the uncoated ones, while the Ω/kft values are about 3 % higher as for the other sizes.
AC Resistance & Reactance — NEC Chapter 9 Table 9
| Size | XL, all wires | AC resistance, uncoated copper | AC resistance, aluminum | Effective Z at 0.85 PF, uncoated copper | Effective Z at 0.85 PF, aluminum | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PVC, Al conduit | Steel conduit | PVC | Al | Steel | PVC | Al | Steel | PVC | Al | Steel | PVC | Al | Steel | |
Conduit columns: PVC, aluminum (Al) or steel conduit. Effective Z = R × PF + XL × sin(arccos PF), tabulated at PF = 0.85; current × Z approximates the line-to-neutral voltage drop. No aluminum values at 14 AWG.