Lighting, Light Fixtures, Ceiling and Exhaust Fans - Bath fan/ light combo?

I currently have a bath light and want to convert it to a light/fan combo. They light is powered by a single wall switch. To tontrol the new light/fan combo can i replace the wall switch with a double rocker switch or do i have to run a new cable from the light/fan combo to the new double rocker switch plate?
Any help will be greatly appreciated.

Thanks

Well, you haven't told use the wiring, so we can't answer with 100 percent certainty.

However, it's a good bet that the cable between the light and the switch has to be replaced.

I got into the atic and the current light is wired from the light down the wall to the switch i will pull off the switch tomorrow to see the connnections there. The new fan light combo has a blue, black, and 2 whites coming from it.

I'm not sure what other info you will need to answer the question. Ask me and I will do my best to provide the info.

Thanks,

Yes, and yes. You can use a tandem switch and you will have to run an additional wire to the switch box. The current feed into the box will be sufficient, and you can use the current outgoing wires to power the light. But you will have to run an additional cable for the fan. You will probably have to drill an additional hole for this cable and should be able to run a "fish tape" down to the electrical box but please turn of the power before doing this. Attach a string to the fish tape and after pulling it out, attach the cable and pull it down to the box. [Improper and dangerous advice removed.] Pay particular attention to the wiring of the switch. They aren't complicated but you can do it wrong. The space within the utility box will be cramped so be sure to push the wires as far back as possible.

Regarding the wires: The whites are ground and will be connected together in the box with the switch. The black is probably the light, the blue the fan. Use a multimeter (resistance check) to confirm which one is for the light and the other will be for the fan. This should also be explained in the installation instructions which come with the fan/light unit.

You need to either add a section of 14-2 or 12-2 or replace the existing section of cable with 14-3 or 12-3. The size will be based on the circuit breaker size. 12 gage for a 20 amp circuit or 14 gage for a 15 amp circuit. Someone else suggested that smaller gage wire would be okay, but that is incorrect advice and needs to be ignored.

The actual connections depend on where the power is and on whether you add a section of two conductor cable or replace the existing two conductor cable with a piece of three conductor cable.

Post back with your decision and additional information when you determine it.

Thanks for the help guys. Based on what I saw in the attic this morning, the cable from the switch is either 12-2 or 14-2
it runs up the wall and over to light. However, if memory serves me correct the line ends there. I don't think this will make a difference.
I was thinking fo just adding a line of 14-2 cable from the fan to the switch. However, if i use 14-3 cable I would remove the existing line and use the new 14-3 by itself. Am I correct. Would you guys advice one method over another.

I will definately turn the power off and will wait for a sound method of installation before I proceed.

Thnaks for the help.

I would add the 14-3 (or 12-3) and then abandon the existing line.

How do I know if I should use 12 gauge or 14 guage cable. Should I look at the other cable in the attic and match that or is there a standard for wiring a bath fan combo. I looked at the unit I bought and there were no specifications for what size to use.

Also when pulling the new cable to the switch should I pull from the top or the bottom.

12 gage wire is used on a 20 amp circuit, 14 gage wire is used on a 15 amp circuit.

Run the new cable into the switch from the top of the box.

Thnaks for the help