Switch between single-phase 230 V and three-phase 400 V. Enter the load in watts (or amps), the one-way circuit length and how the cable is installed — we recommend the mm² size, MCB rating and expected voltage drop.
Copper conductors, PVC insulated, 30 °C ambient. Aim for ≤ 3 % voltage drop on lighting and ≤ 5 % on power circuits. Always verify against local wiring rules (BS 7671, IEC 60364, NF C 15-100, VDE 0100).
For most 230 V household 16 A circuits, 2.5 mm² copper is standard for socket rings and 1.5 mm² for lighting. Long runs (>20 m) or high loads may need 4 mm² to keep voltage drop under 3 %.
Vd = 2 × I × L × ρ / A. For 230 V single-phase copper: %drop ≈ (0.0175 × 2 × L × I) / (A × 230) × 100. Target under 3 % for lighting, 5 % for power per DIN VDE 0100-520.
Yes. Cables in insulation or grouped in a bundle derate significantly — reduce ampacity by 20–40 %. The calculator applies the installation-method factor for you.
Copper for anything under 25 mm² and every indoor circuit — better conductivity, easier terminations. Aluminium only makes sense on long feeder runs at 35 mm² or above, and needs anti-oxidant paste.
Estimates only. Check the paint tin / adhesive bag for the exact coverage of your product.