Drilling into a live cable or a water pipe is one of the most common DIY accidents, and one of the easiest to avoid. Before you hang that shelf, mirror or TV bracket, take two minutes to check what's behind the plaster.
Know where cables usually run
In UK homes, concealed cables are meant to follow set routes, often called safe zones. Treat these areas as "likely to contain a cable" and avoid drilling in them where you can:
- Straight up and down from any socket or switch, all the way from floor to ceiling.
- Straight across from any socket or switch, running horizontally along the wall.
- The top 150 mm of the wall, where it meets the ceiling.
- Within 150 mm of a corner, running vertically.
Check both sides of the wall, because a socket in the next room can mean a cable in yours. And remember that older or altered wiring doesn't always follow the rules.
Think about pipes too
Pipes tend to run straight up or across from radiators, taps, boilers and outside taps. Be extra careful in kitchens, bathrooms and anywhere near a radiator.
Scan with a detector
A wall detector gives you a second check. The Bosch Truvo digital detector works with one button: it detects metal up to 70 mm deep and live cables up to 50 mm deep, and warns you with a traffic-light LED and a tone.
- Switch it on and hold it flat against the wall, away from where you plan to drill.
- Slide it slowly across the area, first side to side, then up and down.
- Mark anything it finds in pencil.
- Scan again from a different direction to confirm.
What a detector can't tell you
A metal and live-cable detector won't find plastic pipes, and it may miss a cable that isn't live at the time. Detection depth also depends on the wall and the size of the object. A clear reading is a good sign, not a guarantee.
Drill with care
- Drill only as deep as your fixing needs. A piece of tape on the bit makes a simple depth marker.
- Go slowly and stop if you feel unexpected resistance or the bit suddenly breaks through.
- If you hit a cable, don't touch the drill bit or the wall. Switch off at the consumer unit and call an electrician.
This guide is general information, not electrical advice. A detector and the zones described here reduce the risk but can't rule it out. If you're unsure what is behind a wall, ask a qualified electrician.
Sources: DIY Doctor: Electrical safe zones
