WIRE & CABLE ENGINEERING

Wire size selector.

Find the smallest copper wire that meets both checks.
Bundle derating and DC and AC resistive voltage drop in one calculation.

Model assumptions. These calculators make simplifying assumptions about wire type and construction, bundling, and the installation environment. They assume constant loading and steady operating conditions; changing loads and transient heating are not modeled.

For more complex systems and loading profiles, contact Lectromec to find out more about our advanced ampacity thermal models.

DC and AC resistive estimate. For AC systems up to 800 Hz, assumes approximately sinusoidal steady loading, near-unity power factor, negligible cable reactance, and negligible AC resistance effects. Enter RMS voltage and current for AC. Use the actual supply-and-return current path; three-phase line-to-line calculations are not supported automatically.

Circuit requirements

Source voltage (DC or AC RMS) V Continuous load current (DC or AC RMS) A Allowable voltage drop V Length units Supply conductor length ft Return conductor length ft Additional circuit resistance mΩ Circuit protection rating A · optional

Supply and return use the same candidate gauge. Include the actual current path; enter measured structure-return or connection resistance in the additional resistance field. The drop limit is your design input. Select a limit appropriate to the aircraft and equipment requirements.

Bundle & operating conditions

Ambient temperature °C Conductor temperature rating °C Operating altitude ft Total wires in bundle Current-carrying wires

Use the most restrictive bundle section along the circuit. This estimator supports up to 45 wires. Temperature rise (rating − ambient) must be 30–300 °C. Voltage-drop resistance is conservatively corrected to the conductor rating; this is not a predicted operating temperature.

Candidate comparison

Copper AWG	Derated A / wire	Ampacity	Drop V	Voltage drop	Combined

Scroll horizontally to see all columns on small screens. The first passing row is the smallest screened size. A voltage drop above supply means the specified current cannot be sustained for that candidate.

For informational purposes only. Results are estimates and do not establish design suitability or compliance. Qualified engineering personnel must review applicable standards, aircraft and equipment requirements, manufacturer specifications, installation conditions, and the complete engineering design before use.