CP-03Check for cables and pipes, and know how to shut things offCables and pipes can run almost anywhere in a wall, not just in the 'safe zones'. Sweep the area with your detector, but still assume something might be there even if it shows clear — detectors miss cables that are deep, in metal conduit, behind metal-backed plasterboard, or confused by a metal stud frame. Before you drill, find your stopcock (usually under the kitchen sink) and check it turns freely, so you can shut off water fast if you hit a pipe. If you have any doubt at all, isolate the relevant circuit at the consumer unit before drilling, and turn off the water at the stopcock before cutting into anything that could carry it.