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What Happens If You Drill Into a Wire Behind Drywall? (And What To Do About It)

what happens if you drill into a live wire behind a wall

It was a simple honey-do job. Just drill a few holes to hang a picture or shelf. Then came the sparks, the pop, and you’re looking at the blackened end of your drill bit as panic set in. What have you done, and what will it take to fix it?

Some call it a rare event to hit an electrical wire while drilling holes through sheetrock. But whatever the statistics, it does happen. And the older or more renovated the building, the higher the chance that wires may be closer than expected to the backside of sheetrock or located in unpredictable places.

What Happens If You Drill Into a Wire Behind Drywall?

If you do drill into a wire behind your drywall, you’ll more than likely know it immediately by the resulting spark, pop, and perhaps a power loss. If none of these things happen but you notice what looks like a bit of wire insulation on your drill or have any other reason to believe you’ve hit a wire, don’t ignore it for safety’s sake.

A wire that is only partially severed could cause a hot spot, which becomes a potential fire hazard even if the circuit was not disabled. There is also the possibility that you could hit a ground or neutral wire or both. In these cases, there may not be a noticeable indication at the moment. You may not realize until later that a particular nearby outlet or light switch has stopped working or is causing a shock when touched.

Household wiring generally falls into one of two categories, lighting distribution or power distribution. Lighting wires usually travel down from the attic area, but power wires may come from either above if you have a cement foundation or below if you have a crawl-space or basement. While all carry electricity, hitting a heavier gauge power wire can have a more spectacular immediate effect and more devastating future effect if not properly repaired.

Look around the area. Are there outlets or switches nearby? Are you near any major appliances? Answering these questions will give you some idea of what kind of wiring may be passing through the wall at this point. A handheld meter or voltage tester can also verify if the switch or outlet is receiving power.

What To Do If You Drill Into A Wire Behind Drywall

1. Turn Off the Power

If a breaker blows, the easiest thing to do is turn it back on see if it works. That may not be a good idea. If there were actual sparks and noises when you hit the wire, you’ll want to leave the breaker off until you actually inspect the damage. And when you begin your repairs, you’ll want to trip or even completely disengage affected wires from the breaker. For your own safety, don’t ever attempt to repair an electrical wire while there’s still power available to it.

2. Inspect the Damage

Before beginning this kind of DIY project, I need to make one point clear. If you don’t know anything about electricity, call someone who does. Don’t endanger yourself or anyone else by trying to repair dangerous electrical wires without the appropriate knowledge of how electrical circuits work. You’ll also need to know the current codes that must be met to protect wiring from future damage.

A boroscope might come in handy to access the damage. This tool runs from around $100-$250 and can have many uses around the house. But if you don’t have one and don’t want to wait, you’ll have to open the wall to visibly inspect the area.

If you have to cut a larger hole to inspect and repair the damage, use a drywall saw set at an angle so that the piece can be fit back in without falling through or needing bracing after repairs. If you don’t have access to this tool, use a shallow cutting implement to cut a hole without causing more damage.

3. Repairing the Damage

Now you can see what kind of damage has been done. You can also see if there are any junction boxes nearby that can help you properly repair the wire. If you have only nicked the insulation and you’re able to free the wire via a nearby junction or switch box, you can slide shrink-wrap over the affected area to restore the insulation.

If any bare wire is exposed and damaged, it will need to be repaired. Never attempt to repair electrical wire by simply wrapping it in tape or screwing on a wire cap outside a junction box. This type of repair will not meet code and creates new hazards over time if exposed to dampness or other foreign matter.

If there’s enough wire to pull the damaged wire into a nearby junction box, you can make your adjustments there. The same applies to any nearby switch or outlet boxes. There’s an abundance of websites to remind you of the proper way to wire these common wall boxes.

If no boxes are near enough or it will not work to pull damaged the wire into a nearby box, there are a couple of ways to repair wires safely where they are.

Insulated splice: For a smaller gauge wire, a simple insulated, crimp-style splice may be all you need. These splices will ensure that no bare wire will be exposed to outside elements.

Cable Repair Kit: A repair kit such as HellermannTyton’s LVRK-L Cable Repair Set may be a good choice for heavier gauge repairs. Check the voltage capacity of any repair materials you use to ensure there will be no chance of hot spots.

There are plenty of online professionals who offer immediate help should you need it. Remember, this is electricity we’re talking about here. Don’t take any damage or repairs lightly.

How To Avoid Drilling Into a Wire Behind Drywall

If there’s one thing that can be learned by this experience, it’s that you don’t want it to happen again! I feel quite fortunate in that while I have listened to and hopefully learned from others’ horror stories, I’ve avoided that particular mishap so far. But I tend to be ridiculously cautious. Here are a few ways to keep a similar incident from happening as you move forward with your honey-do list.

  • Limit your drill depth. A piece of tape around your bit at about 1/2-3/4 inch will help you stop drilling once you’re through the sheetrock.
  • Don’t push it. In the U.S. it’s common to find wires passing through holes drilled in 2 x 4 studs. Codes require a protective metal plate to cover the side of the stud to prevent drilling into the wires. So if you find yourself drilling into heavy resistance, stop. You may have hit a nail plate covering.
  • If the wall you’re drilling into was done right, vertical wiring should be anchored to the center of studs. By limiting your nail or screw length to 1 1/2 inches or less, you greatly reduce your chances of hitting internal wiring.
  • Use a wire and/or stud finder. A wire sensor will indicate the path or power sources in your walls. This can be especially helpful in older or highly renovated areas.

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