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I have 2 circuits of 4 lights connected via two 14/3 cables to two sets of switches that on/off each circuit. Power comes in at Switch1/circuit 1. All works fine.

I want to extend power from second set of switches to new single pole switch just two feet from that second set. The new single pole switch will control one dining room light. How do i extend power to next switch so that it works independent of the other switches?

enter image description here

  • You probably can't since you don't have a constant hot at the second box. You'd have to tie into one of the three-way travelers, making the new switch dependent on the others. – isherwood Mar 1 '18 at 16:43
  • Nice drawing, one hint, on 3-way switches the common screw is black, the traveler screws are both brass. The physical positions of these terminals are not consistent from switch to switch. – Harper Mar 1 '18 at 23:14
  • Is running a cable back to the first switch box an option? – ThreePhaseEel Mar 1 '18 at 23:28
  • Thanks. I decided to use another power into a separate single pole switch and run power from that to a second single pole switch. Just posted a question on that. – Newroof Mar 2 '18 at 16:09
  • I'm curious what kind of software you used to draw this diagram. I'm looking for a better way to depict wiring and I liked your drawing. – Nicknamednick Apr 21 '18 at 11:35
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Let's go to the store and get some colored tape, so we don't lose our minds. We don't need to distinguish two travelers from each other, so a pair of travelers can be the same color. We do however have two sets of travelers in close proximity, and two switched-hot colors which I'm making red and purple.

So now in color:

enter image description here

In order to feed an additional switch+lamp combo, you need always-hot and neutral. Do you see it in the right hand switch box? Yes, you do, but how?

Well, you've got always-hot in one cable and neutral in the other cable -- Oh wait.

You can't do that

You can't pull power off one cable and return it on another cable. Currents must be equal in each cable. The answer is "NO".

It would be yes if they were all wires in one conduit. Using cable between the switch groups sinks you.

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You DO have what you need at the second set of switches. Use the White wire with the black tape on it to feed your single pole switch. The other cable has the neutral wire in it, so you can use this as the return with the new lighting load you'll add.

Preliminary: Turn the circuit off and lock the cabinet door, get a battery light to work with.

  1. Run a 2-wire(Black,White) cable between the new light box and the second set of switches.
  2. Remove the White wire marked with black tape from the common screw of the left 3-way switch and splice it together with two short lengths ("pigtails") of black wire with the same gauge.
  3. Reconnect one pigtail to the 3-way common screw.
  4. Connect the second pigtail to one screw on the new single pole switch.
  5. Connect the black wire of the cable you ran in step 1 to the other screw of the single pole switch.
  6. Splice the white wire of the cable from step 1 in with the other two white wires that are already wire-nutted together.
  • This will give you a light independently controlled. The other lights will not have to also be on. – Nicknamednick Mar 1 '18 at 17:38
  • No, there's a fatal flaw with that. It's not the lines being switched. – Harper Mar 1 '18 at 18:35
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    Doesn't a neutral have to be bundled with the hot it pairs with? – isherwood Mar 1 '18 at 18:43
  • Yes, or with its switched hot or with its travelers. In a single phase circuit, there should always be one wire with current flowing in one direction and another wire with current flowing in the opposite direction in the same cable or conduit. You can't tell by looking at them but electrically that is what is happening. That way their electromagnetic fields are cancelling each other out. The Code allows an exception but this isn't the situation. – ArchonOSX Mar 1 '18 at 19:55
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    Or any number of wires which sum up to the same current as the one wire. For instance in a modern switch loop the black might take 2.03 amps, the red 2.00 amps (for the light) and the white 0.03 amps (for the smart switch). – Harper Mar 1 '18 at 23:16

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