SH-03Run your detector and know your isolation points before drillingCables and pipes can run almost anywhere in a wall, not just in neat vertical or horizontal zones. Run your detector over every mark, but treat it as a warning system, not proof of safety — detectors miss cables that are deep, in metal conduit, behind metal-backed plasterboard, or simply out of range, and a metal stud frame can confuse a cheap detector further. Before you drill, find your stopcock (usually under the kitchen sink) and check it turns freely, and if you have any doubt at all, isolate the relevant circuit at the consumer unit first.