Consolidating two two-gang boxes

I have two 2-gang boxes stacked a few inches apart. Between them they have four devices:

1. Single-pole dimmer for chandelier
2. Single-pole switch for outdoor light
3. 3-way switch for can lights
4. "Mystery" switch that apparently does nothing

I want to consolidate the dimmer and the 3-way switch into the lower box, to disconnect the mystery switch, and to relocate (and consolidate with a separately-switched patio light) the final outdoor light switch. This will leave the upper box free to be a low-voltage device box for an audio controller and intercom device (obviously with no line-voltage connections being made in the box). The conductors in the upper box are long enough to reach the lower box (although I'll have to tape up the conductors to replace the missing jacket, which is not long enough).

Here is a diagram of all the wires in both boxes (ground wires not illustrated):


My plan is to:

1. Remove the mystery switch entirely, capping off the red conductor in the lower box
2. Relocate the chandelier dimmer into the lower box, in the spot vacated by the mystery switch. This should be especially easy, given that the switched wire from that device is in the lower box.
3. Extend the 2-conductor cable that connects to the outdoor light with another
   2-conductor cable, making the connections in the lower box, and extending the new wire into the crawl space and over to another location.
4. Eliminate the two short 2-conductor cables that connect the two boxes, since the upper right wire will replace the right one, and the upper left conductor can be extended to reach the lower box.

There's a few things that concern me:

1. The white wire from the 3-conductor cable in the bottom left is connected via a wire nut to hot black wires. What the what? Is that okay?
2. Based on the cable that the red wire from the mystery switch is part of (it heads up through the wall cavity, presumably towards the chandelier, which is switched by the black wire in the same cable), I'm guessing it used to be a switch wire for a ceiling fan that is no longer there. I'll have to investigate the attic to be sure, but if it's capped off at this end, there should be no problem, right?

Does any of this sound like a problem?

 

Welcome to the forums!

Yes, but probably not anything you can't resolve.

Wrapping conductors, and conductor sets, in tape and running them through a wall cavity is not a compliant wiring method. The 2-conductor cable on the upper right is either the panel feed or a feed out to additional loads, and the 2-consuctor cable on the lower right is the mirror of that. Since those two sets must remain connected, you will have to find a different way to get the conductors from the upper right cable into the lower box.

I was going to suggest this if you hadn't.Right. However, unless there is a splice box in the attic there will not be an accessible location to check there. This question is likely to only be answerable by removing the light fixture. I wouldn't bother. The reasoning is sound.

Since you have access to an attic above and a crawl space below this location you should be able to make splices in new boxes in either or both of those locations that will give you cables with complete jackets inside the wall while removing all line-voltage wiring from the upper box.

All openings in both boxes must be filled or closed when you finish. If that requires replacing one or both boxes then doing that will also give you access to the stud bay for working with both new and existing cables and your low-voltage wiring.

You didn't say which of the terminals on the 3-way switch is the common terminal. From your drawing, however, it appears that it would be the terminal that is on one side by itself, and that it is connected to the load. The two traveler terminals would be the two that are together on the other side of the switch. If so, then the white wire in the 3-conductor cable would be picking up the power for the 3-way pair and it would be connected to the common terminal on the other 3-way switch. It should be tagged with a bit of colored electrical tape or a permanent marker, in any color except gray or green, to designate that it is being used as an ungrounded (hot) conductor.

For now, could you check my guess on the connections on the two 3-ways and tell us whether working through the attic and crawl space will let you install continuous jacketed cables? Thanks.

 

Thank you!

How about something like this Tyco Electronics Romex Splice Kit?

When I first read this, I didn't completely follow. I think now I understand you to suggest that I can remove the top left wire entirely from the wall cavity by cutting it just where it enters the attic, installing a junction box at that point, and running a new 2-conductor cable down through the wall cavity with sufficient length to reach the lower box with shielding intact ... right?

I do intend to completely remove the upper box, and to patch the hole in the wall, so I can install another 2-gang (low voltage) box about 8" higher at appropriate thermostat height. Removing the two short lengths of wire connecting the two boxes shouldn't be a problem for the lower box, since I'll be running (new versions of) the top right and top left illustrated cables into that box through the same holes.

Indeed, it is that terminal -- the "COM" designation got a bit obscured in the scan / resize operation.

I half suspected as much, but couldn't reason out why the other 3-way switch wouldn't simply pick up power from a feed in the box where it is located?

If only the painters hadn't sprayed gobs of tan-colored latex paint all over every conductor in the box, I might be able to tell. :-/

I will try to find where the next switch in the series is, but there are five light switches that control this load, and it may take some effort to find where these cables lead. I could shut the whole house down and experiment with the continuity tester, but I'll probably have to wait until the family's out for a few hours without me. Re: the crawlspace and attic -- I'll have to climb up to be sure, but there's plenty of room to work up there, so long as I can find where the cables enter the space.

Thanks a million for your thoughtful and thorough reply!

 

You identified the load for that 3-way switch as the chandelier. If you're saying that your chandelier can be controlled by any of five switches, then two of those switches are 3-ways and the other three are 4-ways. In any 3-way hard-wired switch setup, the load is connected to the common terminal on one of the 3-ways and the power is connected to the common on the other one. There may be any number of 4-way switches between the two 3-ways, but only the travelers are connected to those switches.See How Light Switches Work.

If there are 5 switches that control your chandelier now and everything is working fine, I would just tag that wire and make sure it winds up connected to the hot panel feed in the end. Also make sure that the common terminal on this 3-way winds up connected to the hot feed for the chandelier, even if you have to replace the top left cable run.

Yeah, hate it when they do that. The paint should peel right off if scraped with a fingernail though, and any tape on that wire should be evident right through the paint anyway, so either it isn't tagged or it was done with a marker.

Yes. I think you'll need to do that twice though. Once each for the top left and the top right cables.

Interesting. That might work. I note that the info says that it's UL & CSA listed, so that's reassuring.

I also note that it says "NEC compliant - article 334-40b, 2005 & 2008 NEC." As I read it, Article 334.40(B) is almost as controlling of the installation method as it is of the manufacturing method. Here's the text, from the 2011 cycle:
What do you think?

 

After some more thought, I may have reasoned it out. The can lights on the 3-way need the feed and neutral to come from the same circuit. The way I've seen most multi-switch setups explained involves picking up the feed in the box with the first switch, and carrying the neutral from that same circuit, along with the two travelers, from switch to switch with a 3-conductor cable. In my case, the neutral from the load is tied to the neutral in the last box, so the feed from that same circuit is picked up in the last box and sent backwards to the first switch using the white wire in the 3-conductor cable. In theory, it should be possible to (although I have NO INTENTION of doing this):

1. Tie the white conductor from the top left cable (which returns the neutral from the can lights) to (and only to) the white conductor in the bottom left cable
2. Remove the remote end of that white conductor in the bottom left cable from the common terminal on the first 3-way switch, and tie it to the neutral in the box with that first 3-way switch
3. Tie the common terminal on the first 3-way switch to a feed line on the same circuit as the neutral from step 2

As I said, I have no intention of doing this, since the circuit works as it should now, and the 6 can lights of 75W each use 450W or ~ 4 amps, and may overload whatever circuit they're added to. But in theory, this would work, yes?

I've seen that product described on other electrical forums as a code-compliant way to join severed conductors without requiring a box for access. I haven't parsed the code before, but I wonder if the relevance of 334.40(B) is with respect to the "tap" function of the kit? If you're merely using it to splice two wires with the same number of conductors (there is a 3-wire version available as well as the one I linked), would any of the 334.40(B) language be relevant? It wouldn't be functioning as a "Switch, outlet [or] tap device[]"

 

Yes. But there's no reason to thing of either switch as "first" or "last."

All 120V loads require that.

Right, it wouldn't. My guess is that they may have just picked up on the most relevant code section.

OTOH, I'm wondering, since neither of us has seen one of these, whether it might be capable of connecting a tap.