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Voltage Drop and Maximum Length Calculator

Calculate AC voltage drop, the entered voltage-drop limit in volts and the user-limit-based maximum route length from entered conductor impedance data.

Inputs

Circuit and conductor data

Range: 0.01–100,000 A

A positive line current is required because maximum length is an inverse calculation. Use RMS current for the operating condition.

Range: 1–100,000 V

Use phase-to-neutral voltage for single phase and line-to-line voltage for balanced three phase. Australian examples are 230/240 V and 400/415 V.

Range: 0–1,000,000 m

Enter the one-way route length to calculate the present voltage drop.

Range: 0.0001–100,000 Ω/km

Enter resistance for the operating conductor condition and size from a verified source; use the same temperature basis as the design check.

Range: 0–100,000 Ω/km

Enter conductor reactance at the operating arrangement; use zero only for an intentional resistance-only estimate.

Range: 0.01–1

Enter the operating displacement power factor used to weight resistance and reactance; distortion PF is not modeled.

Choose single phase for a two-conductor loop or balanced three phase for the √3 relationship.

Range: 0.01–100 %

Enter the voltage-drop limit selected from the project design basis; no universal Australian permitted value is assumed.

Result

Estimated voltage drop (%)
2.18
Estimated voltage drop (V)
5.02
PF-weighted impedance component (Ω/km)
4.1839
Entered voltage-drop limit (V)
11.50
Maximum one-way length at entered limit (m)
68.7
Result
The entered route length is within the maximum length calculated for the entered voltage-drop limit. Confirm cable capacity, fault withstand, installation conditions and the applicable Australian requirements separately.

Formula

Calculation logic

Formula definitions and substituted values.

Before relying on the result

  • Estimate voltage drop across an entered route
  • Solve for maximum length at a user-selected drop percentage
  • Compare the arithmetic result with a limit selected from the applicable design basis; no Australian permitted value is assumed.

Related calculators

Compare the arithmetic result with a limit selected from the applicable design basis; no Australian permitted value is assumed.