Can I use an in-wall splice kit for a partially severed wire?

Those UL-listed in-wall splice kits are technically legal under NEC 334.40(B) for repair work, but they can be a real pain to install correctly in a tight stud bay. Since you've allready lost a third of the copper, you absolutely cannot just tape it. That missing material creates a bottleneck for the current, wich leads to heat, which leads to a fire. The breaker tripped beacuse the screw bridged the hot to the ground or neutral, so the insulation is compromised way beyond just that one spot.

The **non-metallic splice kits** are designed for this exact scenario where you don't want to cut out a giant chunk of drywall for a junction box. But you need to be careful. They require a specific amount of slack to get the conductors laid into the tracks properly. If the Romex is stapled tight to the studs nearby, you might find yourself fighting to get enugh wire to actualy seat in the connector. If those teeth don't bite perfectly, you're just trading one fire hazard for another. If this were my garage, I'd just put in an old-work outlet box right at the puncture site. It’s ussually much easier to pull a little slack into a box than it is to fiddle with those tiny splice kit pins. You can just throw a **receptacle** in there instead of a blank cover. You're in a garage, so having an extra outlet for a battery charger or a tool is actually a benefit rather than an eyesore. It also makes the repair accessible, which is always better for peace of mind. If you do go with the splice kit, make sure you use the right size for the gauge of wire you have. Don't try to force 12-gauge wire into a kit rated only for 14. And please, pull the wire out far enough to see if the heat from the short melted the insulation further down the line. If the jacket looks charred or brittle six inches away, the splice kit won't save you; you'll have to pull a new length from the nearest junction point.

I’ve been in that exact spot before. If you're dead set on using a splice kit, grab the Tyco Electronics CPGI-1116415-2. It’s the only brand I trust for 12/2 Romex becasue the pins acutally hold up. Most of the generic ones are cheap plastic and the teeth bend before they even pierce the jacket.

Just make sure you use a pair of Channellock pliers to snap it shut tight so you get a solid connection. It beats cutting out a massive chunk of drywall, but definitly check if the insulation is charred further back before you seal it up.

I'm with the others on just installing a receptacle. It's way less of a headache than trying to get the tension right on a splice kit. One detail that's easy to overlook is the box depth—if you go with an old-work box for that 12/2, definitely get the extra-deep version. Trying to cram those stiff wires and a receptacle into a shallow blue box is a recipe for a ground wire touching a hot terminal.

Plus, check for a staple right above the puncture. You'll likely need to reach in and pop it loose from the stud just to get enought play to wire the device comfortably.

If you're alredy in the wall, check if there's a nail plate. Sounds like that wire was way too close to the edge of the stud if a screw found it that fast. Once you've got the fix sorted, definitly slap a steel protector plate over it. It'll save you from a "sequel" repair if you hang more shelves later. I've seen guys skip 'em and end up right back here in six months. Plus, since it's a garage, I'd lean toward the extra outlet. You can't have enought spots to plug in a shop vac or a battery tender.

Those splice kits might meet code, but have you ruled out damage further down the line? If the screw stayed in long enugh to trip the breaker, there's a good chance the heat or arc-tracking traveled along the conductors. I've seen cases where the jacket looks okay but the insulation inside is scorched several inches away from the hole. Also, are we sure that's the only spot? If you were hanging shelving, have you ruled out other nicks? It’s pretty common to hit a wire in two spots if you're working along a stud. I'd be nervous about closing that up without checking the rest of the run first.