PR-03Check for cables and pipes before you drillSweep the whole marked area with your detector in both directions. Cables can run almost anywhere in a ceiling void, and detectors miss ones that are deep, in metal conduit, behind metal-backed plasterboard, or clipped along a joist you're not drilling into — so treat the ceiling as live until you've drilled a safe test hole. Find your stopcock, usually under the kitchen sink, and check it turns freely, so you can shut the water off fast if you ever hit a pipe. If there's any doubt, isolate the relevant lighting circuit at the consumer unit before drilling, since kitchen ceiling cables often run across the whole room.