CS-03Do your safety checks before drillingCables and pipes can run almost anywhere behind a wall, not just in the usual safe zones. Run a 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, or behind metal-backed plasterboard, and a metal stud frame can confuse a cheap detector. Before you drill, find your stopcock (usually under the kitchen sink) and check it turns freely, so you can shut off the water fast if you hit a pipe. If you have any doubt at all, isolate the relevant circuit at the consumer unit before drilling.