TR-04Check for cables and pipes, then decide if you need to isolateCables and pipes can run almost anywhere, not just in the 'safe zones'. A detector can miss cables that are deep, in metal conduit, or behind metal-backed board, and a metal stud frame can confuse a cheap detector further. If there is any doubt, isolate the electrics at the consumer unit before drilling, and turn off the water at the stopcock before cutting into anything that could carry water.