Voltage Drop Calculator
Estimate steady-state cable voltage drop using HD 60364-5-52 Annex G resistivities (Cu 0.0225 / Al 0.036 Ω·mm²/m). Enter current, one-way length, cross-section in mm², material, and 230 V 1-ph or 400 V 3-ph — estimate only, verify with a qualified electrician.
Frequently asked questions
What formula do you use?
IEC/HD 60364-5-52 Annex G resistivity path (reactance neglected): 1-ph ΔU = 2 · ρ · L · I / S; 3-ph ΔU = √3 · ρ · L · I / S. Percent is 100 · ΔU / V. ρ_Cu = 0.0225 and ρ_Al = 0.036 Ω·mm²/m.
1-phase vs 3-phase?
Single-phase uses the round-trip factor 2 at typically 230 V. Three-phase uses √3 at typically 400 V line-to-line. Pick the supply that matches your circuit.
Cu vs Al resistivity?
Copper uses ρ = 0.0225 Ω·mm²/m and aluminium ρ = 0.036 Ω·mm²/m (Annex G operating-temperature values as published for this simplified path). Cross-section S is always in mm².
Is this a design sign-off?
No. Results are an estimate only — verify with a qualified electrician. Official design under BS 7671 may need Appendix 4 mV/A/m tables for the exact cable type; temperature, grouping, and reactance are out of scope here.