Extra wires on dual switch install

Question

I installed a ceiling fan with a light fixture in place of a light fixture and ran an extra wire from the ceiling fan to the switch. Would now like to install a dual switch to control fan and light independently. I have 4 wires at the switch now and am not sure how to connect two of the wires to the new switch.

I have a red wire to the fan and I know this goes to the fan wire on the new switch. I have another red that is traveling both up to the fixture and down to an outlet or another switch, I believe. I think this is the hot wire as it was connected to the common screw on the single switch.

I also have two purple wires going to the switch one connected to the top right and one to bottom left, both of which are heading up in the conduit. I know that the wiring goes to a smoke detector before arriving at the ceiling fan/light fixture, if this is important.

There are two white wires traveling through the box. I believe those are neutral. I'd appreciate some insight. Can this switch be installed here? And if so, where do I connect the purple wires?

Answer 1

Was it a single pole switch to begin with? Before running your own wire, there should have just been two wires tied to the switch (and a ground); the power coming in and the wire running out to the old light. The other wires should not be wired to the switch unless you want the switch to cut the items off as well (if they are downstream of it).

I drew up a quick, crude sketch of what you'll need to run this setup, regardless of what else is there. Get it down to the basics first and work up is the best way to troubleshoot.

Coming into your box should be the main hot line, I believe you said it was red. Pigtail off of it to the two commons on your new double switch and wire nut them all together.

Next, take your old wire that ran to your light and connect it to one of the other screws. This is where you'd decide which switch to control which item.

Take your new wire that you ran from your fan and connect it to the last screw. Then back at your fan/light, wire one of the lights to the fan and one to the light. Twist together and cap off the neutrals and you should have a working system.

I'm not certain of what those other wires are there for based on your description.. were they connected to the old switch? But, this will get the fan and light working.

Also, like mentioned in Iggy's answer, this won't allow you to control the fan speed from the switch, it'll just cut it on and off.

Answer 2

I don't think your plan will work, as there's really no way to separate the fan from the light without another wire run just like your light switch, but to the fan. These would also have to be separate at the fan fixture. However, your light setup will turn the fan on with the light from the last fan setting, you're halfway there. Also, you only have a 1-gang wall box & you would need to have a 2-gang to accommodate a variable fan switch. Take what you've got or get an electrician or get the landlord to get an electrician.