Conductor Resistance at Temperature
Resistance of copper or aluminum at temperature.
Example
You enter
- Material copper
- AWG 12
- Length (ft) 1000
- Temperature (°C) 20
You get
- Resistance 1.6 ohm
- Per 1000 ft 1.6 ohm/kft
Checked against published worked examples from: NFPA.
Details, formula, and sources
Formula or tableR(T) = R(20°C) × (1 + α × (T − 20°C)); α copper = 3.93 × 10⁻³ /K; α aluminum = 4.03 × 10⁻³ /K.
Source and editionCRC Handbook material properties; NIST temperature-coefficient values.
Free accessNIST data free at nist.gov; CRC Handbook by name.
What governsEstimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
API field namesmaterial, awg, length_ft, temperature_C, resistance_ohm, resistance_ohm_per_kft
- Conductor purity annealed copper / 1350-H19 aluminumASTM B3 / B231 by name