I have a setup where I have two switchboxes, and three total lights.

Switchbox #1 has two switches in it. A dipole and a three way switch. One switch controls Light Number 1, One switch controls Light number 2.

Switchbox #2 is across the room, and also contains two switches, a dipole and a three-way. One switch controls Light Number 2 (same as the other box), and another controls a separate single-switched light number 3.

Light #1 has the power from the box coming into it, and is obviously connected to Switchbox #1. However, when I disconnect the power to it, but disconnecting the two black wires, all of the lights AND the swithboxes are all dead with no power on any wires.

Light #2 has 3 wrapped wires coming into it. One of these wires has a hot black wire all the time, when all switches area in the off position. Light #2 is controlled by both switchboxes.

Light #3 - Is only controlled by Switchbox #2.

The diagram below shows the hook up. Sorry for the crude drawing. Blue Wire represents the white wire, black the black wire, and green the ground wires. The Orange circles represent HOT wires when all switches are in the OFF position, and no lights are on.

All of these things are connected through the walls - can someone tell me how this should be set up? I would like to add additional lights to the set up - where the ones hooked up to the original light #1 come on when light #1 comes on, and ones hooked up to the Light #2 come on when light #2 comes on.

Switchbox 1 Box #1

Switchbox 2 Box #2

LightBox 1 Light #1

Lightbox2 Light #2

  • Are you planning to wire the additional cables to the light boxes or the switch boxes? Aug 18, 2018 at 19:06
  • No, I was hoping to use the existing switch setup - I just want to add three more lights to Lightbox 1, and one more light to Lightbox 2
    – Derek
    Aug 18, 2018 at 19:29
  • I am also a little confused why lightbox 2 has three wires coming into it. I think the 3-wire cables are connecting the two switcheboxes. Is it possible that lightbox2 also has line power running to it?
    – Derek
    Aug 18, 2018 at 19:31
  • So the cables going to the new lights are going to land in the lightboxes then? Aug 18, 2018 at 20:48

1 Answer 1


Here's how your circuit is connected.

enter image description here

I've changed blue to white, I've labeled the screws on your 3-ways, and I've put red, black and yellow tape on a few wires to designate their function. Red is switched-hot for lamps.

Now, we have 3 separate circuits here in close proximity. I added "Chinese Walls" to separate them. No wire can cross those, except ground.

Now when you want to add additional lamps to a circuit that already switches one lamp, the best place to extend it is from the lamp. But that's not what you're asking, is it? You can extend anywhere you can get switched-hot for that light and the neutral for that light! Neutral from another circuit will not do!

  • For instance lamp 1, you can see the left side of switch box 1 has the actually-red wire and the actually-white wire on the left side of the box. That's an acceptable place to tap for more lamps with lamp 1.
  • Lamp 2, the only place genuine neutral (not white-wire-used-for-another-purpose) and switched-hot (black marked red) coexist is in the light 2 box. That is the only place. You cannot tap switch box 2 because there is no neutral whatsoever in switch box 2. Even if switch 3 brought down neutral, you couldn't use it because it's from a different circuit.
  • Great answer. This validates what I finally came to the conclusion of regarding the light two having separate circuit completely powering it. Once I realized through a lot of testing that the two switches are actually connected to each other, not both through the light, I was able to realize I'm gonna have to pull off the existing fixture to add my lights.
    – Derek
    Aug 19, 2018 at 19:44
  • Two circuits? You may have three. I just removed a couple paragraphs about crossing circuits, and showed the walls in the diagram. Aug 20, 2018 at 2:04

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