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I'm doing some renovating and where I want to put a closet I'd like to put a light. There is a junction box there which appears to have been used as a light before and would be ideal. It has only 1 3-wire coming in and 1 out, twisted together. They moved the light elsewhere. I'm hoping I can use this box for a light with its own switch and somehow get power from it.

So the current configuration goes like this:

 Light 
  ||
  ||
Switch 1
  |||
  |||
 J-box (old light box?)
  |||
  |||
Switch 2
  |||
  |||
Switch 3 (power)

2-wire from the light to the first switch. 3-wire from that switch to the junction box and 3-wire to 2 other switches. Power comes in at Switch 3. Can I get power from this box or do I have to use a new line?

  • @isherwood I've edited to show power comes from the last switch, Switch 3. It appears that there are 3 outlets and two other lights on the same circuit. – fullerm Nov 19 '17 at 2:02
  • What do those switches control? Can any of the three turn the light on or off? -- Also, look at the switches and the connections in the boxes. It looks like switch 2 is a "four-way", ie. it has four terminals (besides the ground). – A. I. Breveleri Nov 19 '17 at 2:23
  • @A.I.Breveleri Each switch can turn light on/off. Yes Switch 2 is a "four-way". Switch 1 and Switch 3 are "three-way". – fullerm Nov 19 '17 at 2:29
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You do not have enough conductors in those cables to add a constantly powered device at the j-box. You would have to either run another wire from switch 1 to the j-box, or abandon the use of switches 2 and 3 and control the existing light with switch 1 only.

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The day is saved by smart switches.

In this case, you reconfigure the circuit for an appropriate smart switch. Locate a "master" smart switch at switch 1, and smart switch remotes in 2 and 3. The 3 wires (besides ground) become

  • neutral (white)
  • always-hot (black?)
  • communications line (red?)

The cable to the lamp is switched-hot and neutral, of course.

Now you can tap always-hot and neutral for a lamp, and either have a pull cord at the lamp, or branch off a new switch loop. Remember switch loops must now be wired in /3 cable and provide a neutral.

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