So, my dining room chandelier had 8 little incandescent bent-tip bulbs, and I switched over to compact fluorescent bulbs. Then I remembered one of the two switches was a dimmer, which won’t work with the CFBs. I bought a 3-way switch to replace the dimmer. The dimmer had two red pigtails and a black, wire-nutted onto two blacks and a white from the box. The dimmer’s two reds hooked up to a black and a white, not, as you’d think, to the two blacks.
My wife asked me this morning, “How do you know which wire goes to which screw?” I said, “The last time I did this, it didn’t work the first time. I switched two wires, and it worked.” Sounds simple, right? :rolleyes:
The switch has 2 dark screws, A and B at the top. Screw C is on the bottom right. The box is grounded, so the mounting screws will ground the switch.
First try. A black, B white, C black. New switch worked, old switch didn’t, IIRC.
Second try. A black, B black, C white. New switch can turn it on and off. Old switch, if the light is already on, can turn it off and on. However, if either switch has turned it off, the other switch cannot turn it back on. :smack:
What should I try next? Wrestling with these heavy solid wires is not easy, and I realize there are many possible choices. Only one is right.
First, you need to identify which two wires are “travelers”. You can do this with an ohmmeter and extended leads. Kill the power, disconnect all wires. Attach one lead of the meter to a wire. Check each wire on the other switch with the other lead. If there is no continuity with any of them, you’ve probably got the hot feed from the panel or the ‘switch leg’ to the light. If there is continuity, then you have a traveler. Continue this for all three wires. The two with continuity will be travelers; then it’s just a matter of getting them connected to the correct terminals, which should be no problem. If the light doesn’t switch properly, change the travelers on one switch. Hope that’s not too muddy for you.
Okay, first of all, wiring a three way switch isn’t hard, but if you don’t know what you’re doing, or how it was originally wired, there are seemingly an infinite number of ways to screw it up.
First step: turn off the breaker connecting the circuit. If you’re not sure which breaker the circuit is on, turn off the mains (always a good idea anyway, because you never know when some idiot has accidentally connected a live wire to the ground). Check to make sure that all wires are dead.
Second step: figure out how the switch was originally wired. You’ll need a circuit tester. (Hint: don’t assume that whoever originally wired the switch up used the correct color scheme.) This is easiest if you have access to all wires, but taking down the chandelier is probably more work than you want, and unless it’s accessible from above not worth the effort. You should be able to open up the other switchbox though, and between those two figure which is connected to what.
Step three: rewire the switches based upon the wiring configuration. See here for wiring diagrams and steps.
Step four: turn on the breaker and test. If all is well, put everything back in the wall and have a celebratory beer/champaign/glass of whiskey. If not, give up and call an electrician.
I took a nap, and I’m back. With your help, I’m hoping I can get it right this time. These diagrams are helping me to understand. I’ll let you know what happens, assuming I’m not electrocuted. Just kidding. I’m not going to touch anything without turning off the breaker. I did have a close call, because I didn’t realize at first that another switch in the same box was on another breaker. :eek:
Half the house is turned off while I ponder this, but fortunately the computer is on its own dedicated line.
I got it done, with your help. Thank you. The old switch is slightly behind the refrigerator, so I would have had to hump the fridge out of the way to get to it with the meter. I swapped another pair of wires, and when either switch was off, the other would not work. I stared at the diagrams some more, and I figured out my next move. RedSwinglineOne’s first link was the most helpful, after I clicked on the stop-motion place.
I’m happy that it’s fixed, and I’m especially proud of not getting mad once.
[QUOTE=RedSwinglineOne
I wouldn’t assume your old switch is hooked up correctly, just because it worked with the old dimmer.[/QUOTE]
When I moved in to my house, my kitchen’s dimmer switch blew out. I pulled it out and as I removed it from the wall, I realized it was a 3-way switch. Odd? there’s no other three way to go with this. I figured maybe there was supposed to be one when the house was built and maybe the drywallers chose to ignore it. I purchased a new three way switch and it didn’t work, returned it figureing it was a dud, got a new one, it too didn’t work. I finally pulled out the plans for my house, and no, there was no other switch. Turned out the dumbass who had the house before me must have tried to install a dimmer, bought the wrong one and got really damn lucky when he wired in the extra wire (to another circuit no less).
So the moral of the story is…just because it worked doens’t mean it was right.
I’ve wired a 2-way circuit (Brit terminology) a different way. First you need to understand that the light fitting itself has three terminals: line, loop and neutral. Power is connected directly to the light fitting’s line and neutral terminals, and the load is hard-wired between loop and neutral. You then have a two-core (plus earth) cable going from line and loop to the switch - so the circuit isn’t complete until the switch closes the connection between line and loop. A single switch can do this by itself, or a two-way switch assembly. OK so far?
Now for the switches. They have three terminals: L1, L2 and C(ommon). The switch connects C to either L1 or L2, toggling when it is flipped. So plainly no circuit can exist between L1 and L2. This will work as a one-way switch if you connect your lead from line/loop to L1 (or L2) and C, when the switch can either close or open the circuit by itself according to its position. But if you connect the lead to L1 and L2, and not C, one switch can’t close the circuit. However…
You now take a length of three-core plus earth (instead of twin and earth) and connect corresponding terminals on the two switches: L1 to L1, C to C, L2 to L2, earth to earth. Now you’re cooking with gas. When one switch is connecting L1 to C, and the other is connecting C to L2, the whole assembly is connecting L1 to L2 and the circuit is closed. But when both switches are connecting L1 to C, or both connecting L2 to C, the circuit is open. Ta-daa.
Three-core and earth is typically coloured red/black/yellow/bare (or brown/blue/yellow/bare) - you sleeve the exposed part of the bare earth wire at the fitting.
I’m not going to touch anything without turning off the breaker. I did have a close call, because I didn’t realize at first that another switch in the same box was on another breaker. :eek:
