I just moved into a home with a bathroom in the basement that has a pull chain light switch. I want to put in a switch to control it. The only thing that complicates it for me is the existing setup. Power goes into the light box on standard romex cable. There is also a 2nd romex cable going into the box, which goes off to another room. These 2 are connected (white/white and black/black) via wire nuts, with a 3rd pigtail going to the screws on the light fixture itself. Normally I'd just run a cable from the new light switch into the light fixture, but the existence of this other cable is what throws me. How do I get this light fixture controlled by a light switch, without disrupting the power that it's feeding into the other room?

 

It is possible the power for this light is coming in and feeding another application. You will need to determine which cable is the feeder (hot). You would also need to run a cable from this box to a switch box, located where you need it. Hook the black wire to one screw on the switch, and the white wire on the other screw. Place a black piece of tape on the white wire to denote that it is really "black". In the light box, after you determine which cable is the feed cable, connect the white pigtail to the white wire (or silver screw) to the light. Connect the white wire from your switch to the blacks, marking the white wire with black tape, too. Connect the black wire to the gold screw in your light fixture. The light will operate off the switch, and the power will go to the other room uninterrupted.

 

thanks for the fast response. I'm afraid I'm still confused, I think your referece to the existing pig tails and connecting one end of them is what throws me. I'm not sure which part of the pigtail you are talking about (where they all come together in the wire nut or where it attaches to the light fixture) Can you lay this out as if these were all new wires and nothing was connected? As if I've got an empty switch box and light fixture, let's say A is the power feed white, B is the power feed black. C & D is the white/black cable that feeds power to another room. So my cable from the switch box to the light fixture is E for white and F for the black. I think that will help me understand more. I hope you don't mind!

 

Does this help you?

 

Can't get clearer than that!! Thanks Ray.

 

that's perfect! thanks, guys. this is a great place. appreciate it