I just bought a new house a couple years ago and got around to changing the recessed lighting with LED bulbs. Turns out I needed to replace the dimmers with an LED-compatible dimmer.The old dimmer was a Lutron type that allowed dimming from both locations. I just wanted to replace it with a simple dimmer on one side of the room and a toggle on the other side.So, in both boxes we have these wires: 1. Black 2. Yellow 3. RedThe way the old dimmer was set up, the "master"dimmer unit had all three wires connected to it. The "slave" unit only had black and yellow connected to it, with the red wire taped off.So I cut the breaker, and I detached both dimmer switches. I turned the power back on and tested with a multimeter. In both boxes yellow was hot; black and red were not. I also found out that connecting yellow to red in either box resulted in the lights turning on.I wasn't familiar with this type of set-up and seeing hot in both boxes of the three-way switch. I guess I was expecting a set-up where only one of the six wires between the two boxes were hot. I also was not expecting yellow to be the hot wire.Anyhow, after a number of fuck-ups and trial and error, the solution that worked in all positions was to connect the blacks as you normally would (to "common" on both the dimmer and the rocker switch, even though it's not hot in either box) and then yellow to one of the traveler connections in each switch.Now everything works perfectly, as far as I can see. I tried every combination I could think of, toggle on and off on one side of the room. Toggle on and off on the other side of the room; toggle on on one side, turn off on the other, vice versa, etc., all combinations work and all combinations respect the setting of the dimmer.I know just because it works doesn't necessarily mean it's right. I also checked the polarity of my light sockets after everything is set up, and the contact point is hot and the sleeve is not, so that looks good to me. via /r/DIY https://ift.tt/2ERrGiU
