For the calculation, a power factor $cosφ=0.9$ is assumed. The power factor is the ratio of active power to apparent power and when the waveforms are purely sinusoidal the phase angle φ between the current and voltage.

IEC 60364-5-52 in Annex G states that the voltage drop between the origin of an installation and any load point should not be greater than:

- Low voltage installations supplied directly from a public low voltage distribution system: 3% in case of lighting and 5% for other uses
- Low voltage installations supplied from private LV supply: 6% in case of lighting and 8% for other uses

$V_{\mathrm{drop}}$

V/A/km

$1000 \sqrt{3} \left(R \cos{\left (\arccos{\left (0.9 \right )} \right )} + X_{\mathrm{c}} \sin{\left (\arccos{\left (0.9 \right )} \right )}\right)$ | three-phase system |

$2000 R \cos{\left (\arccos{\left (0.9 \right )} \right )} + 2000 X_{\mathrm{c}} \sin{\left (\arccos{\left (0.9 \right )} \right )}$ | single-/two-phase system AC |

$2000 R \cos{\left (\arccos{\left (0.9 \right )} \right )}$ | single-/two-phase system DC |

$X_{\mathrm{c}}$

Reactance of conductor [Ω/m]