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Wire Size Estimator
Who it's for: Electricians, service techs, and estimators.
Calculator Inputs
Quick Summary
- Built for: Electricians, service techs, and estimators.
- Key outputs: Suggested conductor size range, Ampacity planning note, and more.
- Use this page for early planning estimates before final code and manufacturer verification.
Inputs
- Load current
- Run length
- Conductor material
- Temperature rating
Outputs
- Suggested conductor size range
- Ampacity planning note
- Voltage-drop reminder
How this calculator estimates results
- Evaluates each available conductor size using the same resistance-based voltage-drop equations as the Voltage Drop Calculator.
- Selects the smallest listed gauge that meets the user-selected maximum drop percent target.
- Returns estimated drop, end voltage, and pass/fail status so users can compare tradeoffs quickly.
Cross-check assumptions with Voltage Drop Calculator for a more complete planning workflow.
Common ranges and tips
- Use measured load amps when possible instead of nameplate assumptions.
- Long runs and aluminum conductors can push voltage drop higher than expected.
- If results are near the drop limit, consider one size up for margin and future load growth.
- Final conductor sizing still requires ampacity, termination, ambient, bundling, and local code checks.
Related Calculators
FAQ
No. This is a voltage-drop-based estimator only and does not replace ampacity calculations or adopted code tables.
Yes. Longer one-way distance increases calculated voltage drop, which can require larger conductors to stay within target limits.
No. Temperature, conduit fill, grouping, and terminal limitations are not applied in this MVP estimator.
End voltage helps show practical impact at the load and makes it easier to compare conductor options before final design.
Disclaimer: Use results for planning only. Final design and installation decisions must follow local code and manufacturer documentation.
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