Safe, easy way to tap into taut NM cable in wall?

Question

I am trying to add a wall sconce. I determined that there is wiring coming down from the attic crawlspace to receptacle low in the wall. I knocked a hole in the drywall as shown above, where it has easy access to the non-metallic cable running down to the receptacle box. However, if I tug on the yellow cabling shown here, it has extremely little give to it. I was hoping to tap into it here, but I am not sure if there’s going to be a straightforward way to do that.

Is my best option to tap in while in the attic and drop an additional cable down to the sconce? Or should I cut the cable here, tap in, and use plastic screw caps and an additional foot or two of cable to reconnect the yellow cable where I cut it? It sounds difficult to do in the constricted space, but not impossible. Advice welcome. Thank you!

Answer 1

A new splice in the wall is not needed in your case (and not desirable)

You're too focused on splicing into the cable in the wall at your drywall cut-out. While that is needed under some circumstances, what you've described in your question indicates that you both have access to the cable in the attic and that the existing cables continue down that wall to a receptacle box lower in the wall. With the availability of either of those things, there's no need to splice into the cable at your current drywall cutout. You can tap into the circuit either in the attic or in the existing receptacle box. Either of those two options should be quite a bit easier than creating a splice. It will also mean that you won't have to add yet another junction box that must remain accessible.

Drop a new cable from the attic

The other answers give you ways to cut the existing cable, but that's relatively difficult. It can be quite a bit of work, and, potentially, ends up with an additional junction box, which has to remain accessible, and likely will be relatively unsightly in your wall. IMO, you'd really only want to go that route if other possibilities are notably more inconvenient (e.g., if you couldn't just drop a new cable from the attic).

It sounds like you have at least moderately easy access to the attic. The normal (and usually easy) way to handle this situation is to just drop a new cable down from the attic inside the wall to the cutout you've already made in the drywall. In the attic, the new cable should be routed all the way back to the breaker panel, if you're using a new circuit. If you're not using a new circuit, then you can tap into the circuit you want to use in the attic. Depending on what your wiring looks like and the circuit that you're wanting to add to, you may be able to find an existing junction box in the attic where your desired circuit already makes a connection (verify box fill). Even if you have the same problem in the attic as you do here of no existing junction box and not enough slack, the attic is a much easier place to add the additional junction boxes which you'll need in order to add a splice to give you enough slack in the overall cable length to route into and out of the junction boxes (i.e., a minimum of 6 inches of each cable is inside the junction box).

Alternately, use a new cable from your cutout to the existing receptacle box

Another option is run a new cable from the cutout down to the existing receptacle box. You can then make the connection to the circuit inside the receptacle box where the other cables already go, assuming there's enough box-fill room and you can appropriately enter the existing receptacle box with an additional cable (will depend on the existing box). This might result in needing to replace the receptacle box with something larger/deeper, but we don't have enough information to determine if that would be necessary.

Answer 2

For practical reasons, you would replace the whole section of cable from the new sconce location to the existing outlet, so that each junction is at a junction box that you'd have anyway. Adding in a short piece of cable means having a pointless extra junction box a short distance from one actually doing something useful, that has to remain accessible forever.

You cannot (as you appear to be suggesting) just put some wirenuts in the wall without a junction box.

If there is slack in the attic, running new cable from there might make more sense.

Answer 3

There are some splices available for in-wall use, but they are really, as I understand it, meant for repairs where there is no other practical option.

A splice normally is done inside a junction box, the junction box must remain accessible, and the incoming wires should be around 6" long, though sometimes you have to make do with what you have.

The solution is two boxes, a couple of feet apart. Cut the cable in between (as far as you can reach from one box or the other, so that you have 6" to work with inside each box. Then you add a new cable segment between the two boxes.

In this case, assuming the hole you already made will be for the sconce, you can either make a new box below it or you may be able to make use of the receptacle box. A lot will depend on how the cable is routed to the receptacle box and secured in place. I would open it up (with the breaker off, of course), pull out the receptacle and see if the cable can be pulled up from the sconce hole. There may be an issue of loosening or removing a clamp (usually not too hard to do).

The problem will be if the cable is stapled to a stud above the receptacle box, which will depend on how the cable was installed. If the cable (and receptacle) was installed before the drywall then it should be secured and it could get tricky. If the receptacle was added after the drywall then it should be loose in the wall and it will just be a question of the box clamp.

Assuming you can make use of the receptacle box, attach a new cable to the existing end of the cable before pulling from above, and the rest is easy.

If you can't make use of the receptacle box then you'll have to make a new hole for a new box somewhere in between the sconce and the receptacle. That new box can have a receptacle, but it doesn't have to. It could just have a blank plate covering it.

And thank you to crip659 for another suggestion:

Unless the existing receptacle box is really full (which sometimes happens), use the sconce hole to drop a new cable down to the receptacle box and pigtail it to the existing wires. Then you don't have to worry about moving and splicing cables. Aside from box fill, the only other issue is getting the cable into the box, which may be easy or may be a little tricky.