CONDUCTORS · CALCULATOR

Power losses in cables

Free power losses in cables: get power loss from current, resistance per conductor and loaded conductors. The formula is shown; verify against the NEC.

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

Current

Resistance per conductor

Loaded conductors

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

THE MATH BEHIND THE ANSWER

Method & assumptions

Ploss = N × I² × R

Equal current and resistance per loaded 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

Current: 20 A · Resistance per conductor: 0.2 Ω · Loaded conductors: 2

Power loss: 160 W

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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