AB-03Check for hidden pipes and cables before you drillCables and pipes can run almost anywhere in a wall, including outside — outdoor lights, doorbells, and alarm sensors are often wired through exterior brick. Run a detector over the marked spots, but still treat the wall as if something's there until you've drilled a shallow test hole and checked what comes out. Before you start, find your stopcock (usually under the kitchen sink) and check it turns, 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.