If you need to drill a hole in the drywall and don’t have a stud finder handy, then the thought of “what happens if you drill into a live wire”? probably crossed your mind. Visions of sparks flying and destroyed electrical cables are probably giving you pause, so it helps to be prepared for all possibilities.
Drilling into a live wire is a fairly rare occurrence, but it can happen when you don’t know exactly what’s behind your drywall, especially in older buildings with odd and unpredictable wiring.
So, What Actually Happens When You Drill into a Live Wire?
If you happen to be unlucky enough to drill into a live wire, then you’ll notice a loud spark, a crackling noise, see flickering lights, and a probably blown fuse. If you hit a ground or neutral wire, you might notice some wire insulation coming out of the drilled hole but no spark or loss of power.
Drilling into a live wire is a serious safety issue, and although rare, has the potential to electrocute someone seriously. These situations can also cause fires to start if a short creates enough of an electric arc to set fire to the wall.
If you do hit a live wire, the first thing to do is to stop drilling or driving the nail, take your hands off the tools, and move away from the work area. Modern drills are designed to be properly grounded, so you should be protected from any serious electric shock.
What to do After a Short Circuit?
Power Off the Circuit
If you drill into a live wire and short the circuit, the next thing to do is find the circuit breaker and ensure the power to the live wire is disconnected. If you’re not 100% sure about where the power is heading, then shut off the power to the entire breaker.
You can also test that the power is completely off by testing an outlet for power using a multimeter or voltage tester.
Never attempt to repair an electrical wire while it’s still under power for obvious reasons.
Inspect the Damage
If you can get access to the area behind the wall, then you should be able to get a good look at the damaged electrical wire. Otherwise, it’s best to hire an electrician to take a look at it and handle the repair for you.
If you take a look at the damaged wire and notice the insulation is only nicked, then you can wrap the exposed wire with electrical tape to restore the insulation and replace the wire. If one or more of the wires are severed, then you’ll likely need a professional’s services to fix the wire properly.
How to Avoid Drilling into a Live Wire?
So, how do you prevent this scenario from occurring in the first place?
While it’s already a fairly rare occurrence, there are certainly a few things you can do to prevent drilling into a live wire in the first place.
- First, don’t drill holes or drive nails deeper than you need to. An easy way to do this is by wrapping some tape around your drill bit at the right drilling depth. Limiting your drilling depth to 1 ½” should ensure you avoid hitting any wiring.
- Be mindful of the stud locations. Modern studs are located either 16” or 24” from the wall edge. This means if your drilling into a stud there is a very low chance you’ll hit any wiring. There are scenarios where wires are run through studs, but if you drill into a stud the odds of hitting a live wire are significantly lower.
- Use a Stud Finder. A stud finder set in wire-tracing mode will detect what is behind your wall (including metal and electrical components). This should give you an idea of what wiring is located behind your intended drilling location, and allow you to avoid drilling into it.
- Watch out for Outlet and Light Switches. A surefire way to drill into a live wire is to drill directly above an electrical outlet! Whenever you drill into the space directly horizontally or vertically to an outlet or switch there is a good chance of encountering internal wiring.