Electrical Circuit Planner: Wire Size and Voltage Drop

One circuit. Two connected checks.

Enter your load and cable assumptions once. Open wire ampacity and voltage-drop calculations with your values already filled in, then compare scenarios in each tool.

This planner prepares inputs for general branch-circuit checks up to 600 V. It does not select a breaker or approve an installation. Motor circuits, special load rules, unbalanced circuits and cable types outside the ampacity tool’s scope need a separate design method.

Need current first? Use the three-phase current calculator. Use actual load current here, before any continuous-load multiplier.

1. Load and supply
2. Ampacity assumptions

Insulated single conductors in raceway. Temperature and grouping are checked separately from voltage drop.

3. Voltage-drop assumptions

How to complete the circuit check

  1. Confirm actual load current and its continuous portion.
  2. Open ampacity to review the smallest listed size meeting that tool’s modeled checks.
  3. Use the AWG and mm² conversion to compare the selected area.
  4. Update candidate area and check voltage drop. Compare another cable area or route length if needed.
  5. Review protection, installation conditions and all requirements outside these models.

What carries between tools?

The ampacity tool receives load current, continuous current, material, insulation, terminal rating, ambient temperature and conductor count. The voltage-drop tool receives current, circuit, voltage, PF, length, area, material, conductor temperature, reactance and target percentage. Links carry input values, not fixed results; the destination calculator recalculates them.