I'm replacing (yet again) my bathroom dimmer switch. The old switch had 3 wires: 2 black and one green. The two black wires were attached to the wires coming out of the wall and the green wire was attached to nothing. The new switch has 4 wires: black, red, red/white striped, and green. Can I attach the new switch somehow? If not, what would you recommend when I only have 2 wires (circa 1930) coming out of the wall (besides rewiring my house)?
Not sure what make and model dimmer you're trying to install, so I'll describe a common installation. Wire colors could vary, depending on manufacturer.
- Black is the common terminal, and is attached to the ungrounded (hot) conductor feeding the switch.
- Red is the switched lead (or a traveler in a 3-way installation), and is attached to the switched hot going to the light.
- Red with white is a traveler, used for 3-way installations. In your situation, you'll just cap this one off.
- Green is ground, and is attached to the grounding conductor.
If you don't have grounding conductors in your home, you could install a GFCI breaker and you'll be code compliant.
Lutron devices typically have a red and a red/white stripped wire, whereas Leviton has two red wires.