I have a three wire circuit wired incorrectly and it doesn't work the way it should.
If the switch with the hot wire is switched on (Box #1), the other switch works as it should (Box #2). However, if the switch in Box #1 is switched off, the Box #2 switch doesn't function at all.
I have a multimeter and was able to locate the hot wire in the first box, and found continuity on the two traveler wires in box #2. The problem is, the remaining wire is not black, it's red and there is ZERO continuity between the hot wire and this remaining red wire.
In this same box (box #2) is a single pole switch that controls the fan motor. I tried taking the not-hot black lead and switching it with the red lead that should be the common for the fan light, but then nothing worked. Not the fan, not the light. I am stumped at this point.
The switch with the hot wire almost works like a drop leg circuit instead of the way it should. Should I take ALL the wires out of box #2 and test each one until I find one that has continuity with the hot wire from box #1?
Best Answer
You may be confused as to how 3-way circuits work, since you seem to be expecting certain colors, and are discussing "on" and "off". 3-ways do not have "on" or "off", they merely have "traveler 1" or "traveler 2".
The two travelers are interchangeable, and always run together in the same cable (with a third wire to complete the circuit). They are almost never yellow, but I recommend you mark them with yellow tape on both ends - it makes it a lot easier to understand and work in 3-way boxes.
They can be any combination of the wire colors in cable - red/white, black/red, or black/white. This can even change in the same circuit! That's why I recommend re-marking them.
I am fond of picking the traveler colors so that the remaining wire is the color of its function: white if neutral (in fact this is mandatory), black if always-hot, and red if switched-hot.
Once you are clear which wires are the travelers, make sure the travelers are landing on the brass screws on the 3-way switch. The black screw goes to the always-hot or switched-hot.