Circuit design

Voltage drop calculator

Uses the mV/A/m method from BS 7671 Appendix 4 for 70°C thermoplastic insulated copper cables. Enter the design current, circuit length (one way) and nominal voltage — result is compared against the percentage limit you select.

Phase

Cable size (Cu, thermoplastic)

Design current Ib

Circuit length L (one way)

Nominal voltage U₀

Percentage limit

Results

mV/A/m applied18.00mV/A/m

Voltage drop5.40V

Drop as % of U₀ (limit 5%)2.35%

StatusWithin limit