lightneutral
I would like to add a new light fixture to a 3-way circuit in my stairway. The new light will be closer to the second switch and therefore would like to wire it from there (the other fixture is in the ceiling of the second floor – so pretty far away).
The current circuit is as the following diagram:
(source: buildmyowncabin.com)
How can I connect my second fixture on the second switch? Can I use the ground of my romex between the two 3-way switches to pass the neutral for my light?
Ok In Tandem so when either switch turns the lights on or off you want the additional light on .. Simple
See those black and white wires that go to the light fixture in your current Original Lamp Fixture .. Wire your new lamp socket right there a black wire to the black and a white wire to the white and your green wire to the fixture ground (green wire) my drawing does not show the ground wire to the additional fixture but make sure you use it! BTW leave your switches alone ..
Done..
EDIT 8 Sept 2017
Make sure you turn your Circuit Breaker off before working on it (TEST that the breaker is off by operating both switches to see if your original light turns on - test with a multimeter to verify that there is no power between white and black on your original lamp), wear some electrical gloves and use the one hand rule - you will be safe that way. I work on circuits AS IF they were LIVE circuits - protects me from my forgetfulness .. or any special surprises. You will need wire nuts (yellow - maybe red) to attach the wires. Black to Black, White to White, and [Green/Copper] to [Green/Copper].
Here's your problem. Up in the light box, you don't know which of those /3 cables goes to switch box 1 vs switch box 2. So here's what I would do...
... after buying a multi-color 5-pack of electrical tape for about $3 because we are going to color-code everything: neutral=white... always-hot=black... switched-hot=red... travelers=yellow or some other color. There are always 2 travelers in a cable, they do the same thing, they are interchangeable, so code them the same color. "Two marked the same color" is pretty distinctive, as we are usually trying to make wires different colors.
Install 3-way switch #1.
We are done in this location, so you can reinstall the switch. Next: Figure out which cable is which up-top.
Mark cable #1 and tape the black and red wires both yellow, since they are the other end of those wires you marked earlier. Always mark both ends of a wire the same. It's downhill from here. Turn the power off.
Let's think about the yet-undiscovered wires. There are two ends of /3 cables - one in the lamp box and one in switch #2. These can only be the opposite ends of the same cable.
Most people want their lamps connected to switched-hot, otherwise it defeats the purpose of switches. Switched-hot is red. We'll make the other two travelers. That's black and white. Mark both ends of the black and white wires with yellow tape.
Fit the 3-way in the far box, with both yellow travelers again going to the brass screws, and the common (red wire) going to the black screw. Do the work carefully, and we are done here. You can close up the box.
Back up in the lamp box, nut together as follows:
Power up, test, should be done.
** Now if you have OCD, and want "both 3-ways down" to be lamp off like I do, and it isn't that way, then go up in the lamp box and swap yellows. Done.
Best Answer
Re-designate the wires between switches to be as follows:
Find and obtain "smart switches" which support this wiring scheme. They would need some wireless or power-line method to communicate with each other.
One option that would work slick for this is neutral required motion sensors, since they would not need to communicate with each other. They need to be "neutral required" types because "don't need neutral" types rely on leaking currrent through the turned-off lamp, and this won't work at all if the other motion sensor turns the light on. It also doesn't play nice with LED/CFLs.