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In my garage I have a three way switch that powers the ceiling lights in the garage. There is one switch near the garage entrance near the garage doors, and one switch near the back of the garage. I also have an outdoor light at the back of the garage that was wired before I bought the house, but never connected, so the wires are just sitting there. There is no power to this light currently.

Is there any possible way to power the outside light off the three way switch?

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  • Can you add photos looking squarely into the backs of the boxes? – ThreePhaseEel Aug 21 '18 at 23:42
  • It looks promising. (But I would add a new 1-pole switch to make the outside light independent of the inside lights.) The whites connected by the orange nut are possibly neutrals. The blacks connected by the yellow nut are possibly line hot. The white of the outside light would be connected to the white and the line hot to one side of a new switch. The black to the outside light to the other side of the new switch. – Jim Stewart Aug 22 '18 at 1:09
  • Normally in 3-way circuits, no - because you need hot and neutral, and those are not normally found together in a 3-way. However it appears other things are going on inside this box, so maybe. Also, a traditional 3-way can be forced to provide hot and neutral by converting it to "smart switch 3-ways". – Harper Aug 22 '18 at 3:27
  • I've updated my original post with two more photos, let me know if you need any other photos to see what is going on in the box, or if what I am asking can even be done. There really is no way for me to easily run power to this switch, so my only option is to get power off of this 3-way if that is even possible... – Giancarlo Massaro Aug 22 '18 at 10:34
  • You and I are talking in different ways about the same solution. When you mentioned using the 3-way switch I thought you meant to control the outside with the 3-way, but evidently you didn't mean that. As the answer below explains, get line hot before the 3-way switch (it is irrelevant that there is a 3-way switch and no need to mention it). – Jim Stewart Aug 22 '18 at 14:20
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Take a look at how three way switches are wired. (The actual physical layout of the devices may be much different, but this is how the connections work.)

three way switch wiring

Note that the common from one switch goes to the breaker, and the common from the other goes to the light.

IF the cable to your outside light is in the same box as the switch fed from the breaker

AND the circuit's neutral is in the box, as well as the common hot / travellers

THEN you can tap the circuit ahead of the switches to power the light.

It looks like this is probably the case. It looks like the neutral is coming in on the same cable as the hot.

Not sure whether this switch is the one fed from the source or the one that connects to the light. You could verify by seeing if power cycles on the common terminal when you move the switch, but unless you're super confident working with a live box open, I think it's best to just try it and see. No sense working around energized conductors if you don't have to.

What you'll want to do is add the white to the white from the outside light to the splice with the other neutrals. Also add the ground to the other grounds.

I recommend the push in type connectors unless you've had some practice splicing with wire nuts, I think wire nuts are better once you have some proficiency, but the push in connectors are hard to mess up.

push in connector

You'll want to connect the common, the source hot, and the outside light hot with a pigtail - for this purpose, about 9" of #12 black wire:

  • Remove the black conductor from the common screw.
  • connect one end of the pigtail to the common screw terminal
  • splice the other end of the pigtail, the black that was on the common, and the black on the cable to your outside light, with a push in connector.

(This picture shows a pigtail with a receptacle but it works the same with a switch terminal.)

pigtail

If you lucked out and the wires are in the switch nearer the source, your outside light will now be energized at all times. If it switches on and off with the three way switches, it's in the wrong box and you have a bigger project getting it to work the way you want.

The last step will be to add a single pole switch to the outside light.

To do this,

  • remove the black wire from the outside light from the push connector by pulling it lightly while twisting it back and forth.
  • connect a new black pigtail to the other screw terminal on the switch.
  • push the other end of the new pigtail into the connector with the other black wires.

Sketch:

sketch

  • I appreciate the in depth reply. I'm having trouble following though. Anyway you could look at the pictures I posted above and show a crude wiring diagram? 1) Sounds like the outside light neutral wire will get added to the other neutrals. 2) Add a pigtail to the existing 3 way, connect that with the black conductor and and the black cable for the outside light? – Giancarlo Massaro Aug 22 '18 at 12:26
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    Appreciate your help, I got it working! – Giancarlo Massaro Aug 23 '18 at 9:22
  • @GiancarloMassaro Way to go! – batsplatsterson Aug 23 '18 at 9:38

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