electricalsmart-switchwiring
I've replaced a number of switches in my house following the Lutron instructions, but the wiring below is not covered.
My question is: on my new Lutron switch (one is already visible in the picture), would I cap wires "A" and "B" together with the black wire on the Lutron switch to be installed?
To make wiring easier, could I just cap wire B into group C?
Also, this is a new house (just built four months ago). Is this a standard way to wire a house?
Thanks all!
It sounds like your wiring is like this:
I believe the switch you took a picture of is the one on the left. If so, it looks like it's wired correctly: the black screw is usually common, and it seems to be coming from the red wire nut, which is the power source (am I seeing that correctly?)
If the other switch is turning on/off the light, regardless of which position this switch is in, then it is very likely this is a defective switch.
However, if it is only happening when this switch is in one particular position, then it's highly likely one of the two switches has the common wire connected to one of the traveller terminals. It could be either one.
If you can determine which wire goes where (the biggest hint is that the traveller wire is 14-3 while the others usually aren't), then you should be able to match it up to the wiring diagram here.
Too bad I haven't updated answer when I rewired everything - but better late, then never, right? Here are the answers to my questions:
Best Answer
A and B are already connected. The switch in the photo provides both backstab and screw connections which are internally connected within the switch. The builder prefers backstab connections (because they're faster; their poor reliability isn't his problem), and when he needed a second connection he used the screw also.
It looks like A is a pigtail from the wirenut to the switch. I imagine that before, it was a jumper to the other switch, but then, you added that smart switch, which necessitated a pigtail. Given the presence of the pigtail, sending B to the switch is stupid. B should immediately be pried out of the switch and added to wirenut C.
From there, if you are replacing that switch with another smart switch, I imagine A will be replaced by the smart switch's pigtail.
To help you lose your mind less in that box, look at the wire that attaches to the left smart switch's red wire; I would tag that with red tape. The right wire on the right switch, I would tag that with blue tape. They are both switched-hots going to a light or fan.
Remember you must never, ever put a dimmer on a fan or receptacle! Check all your receptacles and make sure they are not switched by any of these switches (this is a common "feature" in newer homes). If you really, really want to do that, there are a couple of technical solutions.