AB-04Mark bracket positions and check for hidden cables and pipesHold the headrail in place, level it, and mark each bracket hole with a pencil. Run your detector over every mark - but treat it as a warning, not a guarantee, since it can miss deep cables, cables in metal conduit, or anything behind metal-backed plasterboard, and a metal stud frame will confuse a cheap detector further. Avoid drilling directly above sockets or switches, where cables commonly run vertically, and if you're not confident the area is clear, isolate the circuit at the consumer unit first.