There's no problem with type NM cable above either a dropped or drywalled ceiling.

HOWEVER...all splices must be within an accessible box. Now, with removable tiles in a suspended ceiling, the box above the ceiling would be considered accessible. If you drywalled over it, it is NOT accessible. An access panel is acceptable but relocating the box might be a better idea.

You need to make sure the box is sufficiently sized for the number of wires and devices within it. Note that only the first receptacle in the circuit needs the GFCI, the subsequent ones can be wired to the protected (LOAD) side of the first GFCI. The other alternative is to use a GFCI circuit breaker for that circuit.

A three way should indeed have another switch somewhere (if there are three wires connected to it not counting the ground). It's possible that they used a three-way as a regular switch (if there is only two wires) or the other switch is removed and they just connected the common to the traveller in the box that it used to be located in.

Thanks, Ron.

I wasn't concerned about the romex above the ceiling as much as the stuff currently hanging out of the ceiling.

The box looks like it was originally partially buried by whoever framed in the shower enclosure a couple decades ago. I'd guess that was around the same time that the drop ceiling was placed in. So, relocating that junction would be ideal if I can work out where it's actually running up to the box. The switch looks like it runs down, which makes me hopeful the romex is actually going up the wall behind the box, rather than through the ceiling. It would be much easier to access that way, and probably less destructive.

The box is sized at ~22 cubic inches, which I think is sufficient for the 6 wires + a gfci box. That's why I'm questioning if it is more about my wire-arranging skills than the box. I'm inclined to buy a larger box, especially as this is the box under the sink, even if it is achievable.

One other thing I'm running into is the presence of what I think are some old gas lines in my ceiling boxes. I'll need to start a new thread about that one. I'm 99% sure they are decommissioned (no cap on them), but they will be another interesting project.

Thanks again.

The way I do it is to fanfold the wires just slightly shorter than the height of the box (this I do at rough in). Then you pull them out to connect to the device, and they more neatly (and compactly goes back in).

In an older house, the boxes may indeed contain gas lines (especially sconces). You would probably do better to abandon those and install new boxes.

Thanks again, Ron. I'll try the fanfold technique and see how that works for me.

With the gas line, should I be able to just unscrew the pipe from some point? I assume they are non-active lines given the open hole at the end, but I am hesitant to mess with anything that might open up a can of worms elsewhere. I can't imagine that an active line would be connected to a line that is open, but it's always best to err on the side of caution with gas.

Update:

I spent a remarkable amount of time up on a ladder yesterday working on the wiring in the bathroom. The situation in the ceiling and space above is interesting.

1 - It appears some of the ceiling is 2 layers of drywall with the original lath underneath it. Other areas seem to be more of a sandwich of drywall, plaster, and lath.

2 - With the help of a prybar, I was able to finally remove the old shallow fixture, which had been buried twice - once in a remodel where they built the wall over half the box, and again when I had drywall put over the ceiling's sagging plaster.

3 - Once I uncovered the box, I was able to see that the wiring coming down from the cavity above is K+T, which was spliced to 14-2 NM.

4 - Mineral wool seems to really irritate my skin. My arms looked like I had mild sunburn all day yesterday! Any tricks for keeping this stuff up where it belongs, rather than falling out all over the place? By the way, the K+T isn't buried in it, but seems to be running above it and coming down.

So at this point, I'm running into a couple issues:

1 - A standard remodel ceiling box isn't going to do a great job of fitting over the multiple layers of ceiling that are in place. Since most of them aren't even fixture rated in the first place, my thought was to cut a hole where I want the fixture and use a fan-remodel brace and box. However, the same issue is showing up -- the thickness of the ceiling prevents the brace from attaching to the box. Do they sell extended length boxes? Certainly others have placed drywall over their plaster before, and have had to contend with this.

2 - Because of the location of the old wiring, I'm not sure how exactly I want to deal with splicing the 12-2 to the K+T. Remove and replace isn't a viable option, and the K+T is basically in good shape. See issue 3.

3 - I'm now the proud owner of an approximately 6x6 hole in my shower ceiling where I freed up the old box. This hole runs in the same joist bay as the hole for the new fixture, but I do need to splice 12-2 a few feet over in order to power the new light fixture.

I thought I could use a remodel box with a blank cover, but that seems to not be bearing out very well, either in terms of cutting out the hole for the box or getting the fit right. Anyways, those plastic cable clamps and the K+T are a bit unnerving. So I'm back to thinking that maybe an access panel makes the most sense, in terms of keeping the splice accessible, but I still need to put it inside a j-box, yes? Does that j-box need to be fastened to a joist?

Thanks all - this project was supposed to be a couple hours, but has bloomed into a couple days.

Wear long sleaves and gloves. Rockwool is similar yet different to fiberglass.

If the attic is accessible, you can make splices in boxes there that don't have to be visible from below.

Special terminal fitting boxes are made for making K&T connections. You can not make a flying (outside the box) splice to other wiring systems (like they did between K&T and K&T).

As for the thicker ceiling...use a standard (not remodel box), you may need to add a 2x4 or something to mount it to if there's no convenient framking.

Thanks, Ron.

The attic isn't accessible, so I think I need to provide access via a box.

I'll have to look into the specific fitting for the K&T connections.

I'm going to be getting a book out of the library titled "Your Old Wiring" It's supposed to be quite informative about how to deal with these kinds of things.

There's no way into the attic space? Are you saying the only way up there was through some non-permanent hole you made in the ceiling?

Yes - to the best of my knowledge, there is zero access to the attic from anywhere in the house.

It's a small rowhouse, less than 950 sq ft. Unless there is some way it could be access from outside or via another rowhouse, I'm pretty certain that there are no other points of access.