Three-phase systems
Balanced three-phase current: the preliminary calculation
See why line voltage, active power and power factor matter in a balanced three-phase current estimate.
Open three-phase current calculator →
What this calculation is for
Balanced three-phase current is commonly estimated from active power divided by the product of square root of three, line voltage and power factor. The result assumes a balanced, sinusoidal load.
How to use the calculator
- Use the line-to-line voltage at the proposed supply point.
- Enter active electrical power and a realistic operating power factor.
- Calculate the line current and examine the equation with substituted values.
- For an unbalanced or nonlinear load, use phase-by-phase measurements or a suitable study instead.
Useful for
- • Preliminary feeder current estimate
- • Motor and process-load design discussion
- • Load-schedule checking
Fields explained
Active power
Electrical active power, normally in kW.
Line voltage
The line-to-line voltage, not phase-to-neutral voltage.
Power factor
The assumed or measured operating power factor.
System assumption
The method is for balanced three-phase AC only.
Important limits and next checks
Preliminary engineering aid only. This article and its calculator do not provide an approval, certificate, compliance determination or installation instruction.
- This is not a fault-current, starting-current or harmonic calculation.
- Cable, breaker and protection choices still need independent checks.
Verify applicable laws, rules, standards, manufacturer data and project conditions with a qualified electrical professional before construction, procurement or regulatory submission.