CONDUCTORS · CALCULATOR

Cable temperature from resistance

Free cable temperature from resistance: get estimated conductor temperature from reference resistance, measured resistance and reference temperature.

Written by Chameera Sampath · Not yet reviewed by a licensed electrician. See the methodology.

US (NEC) only · NFPA 70 / NEC — locally adopted editionDefaults are US values. Verify the locally adopted NEC edition and project data.Official reference ↗

Project inputs

Measurements

Reference resistance

Measured resistance

Reference temperature

°C

Temperature coefficient

1/°C

Updates as inputs change. Unit changes preserve the same physical values.

THE MATH BEHIND THE ANSWER

Method & assumptions

T = T0 + (R/R0 − 1) / α

Resistance thermometry, not prediction from load. Measurement and coefficient must match the conductor.

Results do not check every aspect of an electrical installation. The calculators follow US (NEC) practice only; a regional preset changes defaults such as voltage and units, and no result certifies NEC compliance.

Sources and validation →

Worked example

Reference resistance: 1 Ω · Measured resistance: 1.2 Ω · Reference temperature: 20 °C · Temperature coefficient: 0.004 1/°C

Estimated conductor temperature: 70.891 °C

This example uses the stated inputs; results for the entered values appear above.

Explore the conductors branch →See the related electrical concepts →

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