UK Voltage Drop Calculator
Calculate voltage drop for single-phase and three-phase circuits. Ensures compliance with BS 7671 (IET Wiring Regulations).
Voltage Drop
Cable Sizing
Maximum Length
Voltage Drop Result
Voltage Drop in the UK
According to BS 7671, voltage drop should not exceed 3% for lighting and 5% for other circuits. This calculator helps ensure your installations are compliant.
Frequently Asked Questions
3% for lighting circuits and 5% for other power circuits (BS 7671).
Excessive voltage drop causes equipment to underperform, overheat, or fail prematurely.
Copper has lower resistance and is preferred for most installations, though Aluminium is cheaper for large cables.