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Voltage Drop

Voltage drop calculations for single phase and three phase systems.

Standard Reference IEC 60364-5-52:2009 + AMD1:2024 Clause 525 and Annex G Conductor resistance reference: IEC 60228
FORMULA USED
u = b × (ρ1 × L / S × cosφ + λ × L × sinφ) × IB
I : Load current
L : One-way cable length
R : Conductor resistance at selected temperature
X : Cable reactance
cosφ : Power factor
K : System factor
n : Parallel conductors per phase
b : Annex G circuit coefficient, 2 for single phase and 1 for three phase
ρ1 : Conductor resistivity in normal service for IEC Annex G method
λ : Reactance per unit length for IEC Annex G method
Standards and data logicIEC 60364-5-52 Clause 525 and informative Annex G provide the voltage-drop guidance, Table G.52.1 limits and an informative calculation method. In IEC Annex G mode the calculator uses the Annex G normal-service resistivity and fallback reactance data stored in SQL. Detailed Cable Data mode uses the shared conductor database and allows calculated, IEC 60228 maximum, or manufacturer/manual resistance together with cable reactance.
IEC Annex G uses the informative Annex G parameters. Detailed Cable Data uses the selected conductor resistance and cable reactance data.
DC 2-wire, single-phase AC or balanced three-phase AC.
V
For three-phase use line-to-line voltage. For single-phase use circuit voltage.
A
kW
Used for AC calculations. Value must be greater than 0 and not greater than 1.
Lagging is the normal inductive-load case. Leading loads may produce voltage rise rather than voltage drop.
Hz
m
Physical one-way route length. The formula applies the correct circuit/system factor.
Uses the same SQL conductivity records as Conductor Resistance.
mm²
mm²
Used for the calculated conductor resistance.
Detailed Cable Data mode can use calculated DC resistance, IEC 60228 maximum resistance, or a manufacturer/manual resistance value at the selected temperature.
Ω/km
Resistance at the selected conductor temperature. For AC calculations, manufacturer AC resistance is preferred when available.
m/(Ω·mm²)
Loaded from the shared SQL conductivity table and may be edited for the calculation.
°C
Choose a SQL default or enter a manual cable reactance.
Ω/km
Use manufacturer cable data whenever available.
Number of identical parallel conductors or cable sets sharing current equally.
IEC 60364-5-52 Annex G profile or Custom Limit.
%
Optional allowance for main wiring systems longer than 100 m. Apply only when the Annex G condition is applicable.
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