Cable Size Uk: How To Calculate

How much current will the load actually draw?

In the UK, you don't just guess 2.5mm² for sockets. You must calculate the to prevent fire (overheating) and unacceptable voltage drop. how to calculate cable size uk

: For a single-phase 230V resistive load, divide the power in watts by the voltage: How much current will the load actually draw

). Standard UK ratings include 6A, 10A, 16A, 20A, 32A, and 40A. Free Cable Sizing Calculator BS 7671 - ELEK Software : For a single-phase 230V resistive load, divide

Once the cable can safely carry the current, the next critical step in the calculation is checking for "Voltage Drop." UK regulations stipulate that the voltage drop between the supply intake and the terminal of equipment must not exceed 3% for lighting (6.9V) and 5% for other uses (11.5V) for a standard 230V supply. As current flows through a cable, resistance causes the voltage to drop; the longer or thinner the cable, the greater the drop. Therefore, the cable size selected based on current carrying capacity must be cross-referenced with its length. If the voltage drop exceeds the legal limit, the cable size must be increased, regardless of whether the smaller cable could technically handle the current.