Tom snorted. Dave wasn’t here. Dave didn’t have to sign the Electrical Installation Certificate. Dave wouldn’t get sued if the cable melted and burned the house down.
He turned to Table 4Ab. For 16mm² cable, volt drop was 2.8 mV/A/m. Run length: 35 meters. [ Vd = (2.8 \times 48 \times 35) / 1000 = 4.7 \text{ volts} ] Max allowed? 5% of 230V = 11.5V. He was safe. But if he’d used 10mm²? 4.4 mV/A/m would give 7.4V – still legal, but pushing it under full load. cable calculations bs7671
“Dave’s 2.5mm would be a fuse on a wire,” Tom muttered. “Death in a plastic sheath.” Tom snorted
The big red book sat on the dashboard. Not a manual. A lifeline. BS 7671 isn’t red tape. It’s the difference between a switch that works and a funeral you pay for. Dave wouldn’t get sued if the cable melted