KN-04Check for cables and pipes before you drillSweep the detector over your marked points, but still treat the wall as if something could be there — detectors miss cables that are deep, in metal conduit, behind metal-backed plasterboard, or outside the usual safe zones, and a metal stud frame confuses cheap detectors further. Find your stopcock now, usually under the kitchen sink, and check it turns. If you have any doubt at all, isolate the circuit at the consumer unit before drilling, and turn the water off at the stopcock before cutting into anything that could carry water.