There are a lot of questions about this topic, but I'm feeling a little dense and want to make sure I do this correctly. I have a small office in my basement. Power runs from the breaker box to the switch, then from the switch to the light. The light is the only thing on the circuit right now. I want to add a new light and switch, where the new switch will be 10' away or so on another wall outside of the office. Everything is open except for the existing light, but I do have access to the existing switch.
Can I run a cable from my existing switch to the new one? What would the wiring diagram look like for that?
Best Answer
Yes, you want to tap off the existing switch.
First, get a 5-pack of colored electrical tape ($4 at the big-box). Go into the existing switch box, make sure the black wires are switched and not the white (if not fix it). Find the cable to the existing switch; the black wire will be switched-hot. Mark it with red electrical tape. Now, everything in the box is color-coded by function.
Now, bring the black-white /2 supply cable to the other switch-light into the switch box. Match up similar colors. And yer done!
If you need to bring 3 wires together, use a wire-nut. If you need to tie a second wire to a wire that's already going to a switch, use a pigtail with a wire-nut. Alternately you can upgrade to more deluxe $3-range switches which have a feature called "Screw-and-clamp"; these switch screws can take 2 wires each.