HTHOMETALLYTHE PRACTICAL HOME GUIDE

Electrical power/ CALCULATOR

Single-phase copper voltage-drop screen

Estimate the resistive part of voltage drop and cable heat for a two-conductor single-phase run.

Measure the actual route from supply to load; the return conductor is included by the formula.
Use the applicable steady current after deciding which loads can run together.
Use the actual conductor cross-sectional area, not cable outside diameter.
Nominal voltage used for the percentage comparison.
Estimated resistive voltage drop

5.29 V

Estimated voltage drop

2.30 %

Screened voltage at the load

224.71 V

Estimated cable heat loss

66.7 W

Two equal copper conductors at reference resistivity 0.0175 Ω·mm²/m and steady current. Reactance, power-factor angle, harmonics, conductor temperature, terminals, protective devices, parallel paths and supply impedance are excluded. This is a resistive voltage-drop screen only; ampacity and protection require a separate design.

FROM ESTIMATE TO ACTION

Use the result, not just the number.

01

Verify the inputs

Measure or document each input. If a value is only an estimate, record its source and test a conservative alternative.

02

Keep the calculation traceable

Save the input link or copied result together with the date, units and assumptions. A number without its inputs cannot be checked later.

03

Confirm the decision

Compare the estimate with the related guide, current product data and requirements that apply at your location before buying or building.

Inputs to verify

One-way cable length (m)
Measure the actual route from supply to load; the return conductor is included by the formula.
Steady design current (A)
Use the applicable steady current after deciding which loads can run together.
Copper conductor area (mm²)
Use the actual conductor cross-sectional area, not cable outside diameter.
Supply voltage (V)
Nominal voltage used for the percentage comparison.

Continue your calculation

Electrical power

Single-phase AC load current

Convert real input power, voltage and power factor into apparent power and approximate steady current.