Hello,
I am replacing an old dimmer switch with a smart one (TP Link HS220). This dimmer switch controls 6 outside can lights (PAR38) on my front porch. I have already replaced the 6 lights with LED retro-fit assemblies. There are 3 wall switches in the same box. The 2 on the left are 3-way switches for inside lights. There are 2 other switches at the other end of the hallway for those same lights, so definitely 3-way switches. The old dimmer is a Leviton with 1 red, 2 blacks, and 1 green. This dimmer is the ONLY switch that controls the porch lights. There is no other switch. All the above is fact. (See pic 1) The rest below are assumptions.

There are 4 bundles entering the box and there is a label inside that I am assuming to be the order from left to right. 1- Inside light, 2- Inside light, 3- The run from the fuse box, 4- Porch lights. (See pic 3).

Old switch: Red lead goes to the green wire nut. I believe this to be the line in (hot). Green lead is ground. First black lead goes to the red wire of the bundle to the porch lights. The 2nd black goes to the black wire of the bundle to the porch lights. No neutral on this switch.

THE PROBLEM: The smart switch has a terminal for Line and one for Load, and neutral and ground leads. Too many wires on the old switch! So from what I thought, there were 2 loads going to the porch lights. Maybe they split 3 on each? It didn't make sense. So I disconnected the black to black connection and all 6 lights came on (See pic 2, the black wire is capped off out of view). Then I switched to try the other so I disconnected the black to red connection and put the black to black back together and no lights came on.

MY CONCLUSION: The black wire to the porch lights wasn't necessary.

So I was proud of myself for figuring this all out (with some help) and put it all back together and set up the smart switch and was having fun with that, then I decided to try the other 2 switches to the inside lights.....

THE NEW PROBLEM: Both inside lights were dead. The switches were not turning them on.

I removed the switches and pulled out the wires to make sure nothing came apart. All was fine. So that is where I am right now. The mystery black wire that I believe to be going to the porch lights is obviously needed for the inside lights. I just don't know where to put it. I want to say again that it is not a 3-way situation with the dimmer. There is only this switch to control the porch lights. The old dimmer may be a 3-way switch but I can't figure out how it all goes together!

Any tips/hints/solutions will be greatly appreciated! Attached 3 pics to help see the situation.

Thanks!

 

By looking at your pictures it appears to me that the old dimmer is a three-way switch. I have never seen a two-pole dimmer or a double switch that is a dimmer so a three-way is the only logical explanation how it was wired. I am not saying that the wiring is a three-way setup. There could have been another switch someplace and it is just bypassed or just skipped altogether.

I would first try to find the location of the three-wire cable and see how it is wired. The first place I would look is at the end of the hall where the other three ways are, or perhaps the garage. You could also look at the first porch light.

I do not understand why the other lights do not work as the home run is there. Take a meter and see if you have 120 volts at the home run wires (hot and neutral).

 

I circled the three wire porch light feed in blue. That is definitely wired as a 3w circuit. Very possibly it was converted and covered over. Could be a real problem in the future.

As Tolyn said..... the feed is coming into that box on a dedicated cable. Therefore it doesn't rely on the porch light cable for power. If the porch lights are working then the most likely problem is that green wirenut connection OR the white neutral splice.

 

Thanks for the tips. I hope to get back at this later today to check these things mentioned. I'm really curious to see what is at the first light on the porch if I can access it above the can.

 

Update: Everything is working great now.

So it turns out that in a room that isn't used often there is another door to the porch which has been opened maybe twice in 20 years, and next to that door behind some furniture is the other 3-way switch for the front porch lights. My bad, I should have figured that out earlier!

When I get into the porch light closest to the front door where I'm installing the new switch, I figured out that it wasn't the first light, it was the last light in the run. Then it all made sense. I took the 2nd switch out of the loop by connecting the proper wires in the box to make this a 2-way setup.

Then I just re-did the large hot and neutral bundles to make sure they were really tight and all worked properly.

Thanks for the guidance!

 

Good job. Thanks for letting us know how you made out.