Bathroom fan using switch loop

crescere · 08-17-2012, 09:15 AM

Hello, and thank you for providing this resource. I am installing a new bathroom fan next to an existing ceiling light. The light is powered by what I think is called a switch loop where the power goes to the fixture and a hot white wire returns to the switch.
Can I power the fan the same way by borrowing power from the light, and using the switch loop method to also power the fan? I will just power both switches with a 12-3 cable. Is there any problem powering a bathroom fan in this way?
While I am asking about the fan is there a trick to connecting the stranded wires of the fan to regular cable? Thank you.

rjniles · 08-17-2012, 10:02 AM

As long as you are OK with the fan and light working together, just run a 2 wire cable(with ground) from the light to the fan.

If you want the fan and light on separate switches, you need to run a 3 wire cable from the ceiling to the wall switch.

Stubbie · 08-17-2012, 10:23 AM

Quote:

Originally Posted by crescere

Hello, and thank you for providing this resource. I am installing a new bathroom fan next to an existing ceiling light. The light is powered by what I think is called a switch loop where the power goes to the fixture and a hot white wire returns to the switch.
Can I power the fan the same way by borrowing power from the light, and using the switch loop method to also power the fan? I will just power both switches with a 12-3 cable. Is there any problem powering a bathroom fan in this way?
While I am asking about the fan is there a trick to connecting the stranded wires of the fan to regular cable? Thank you.

That's fine .. are you going to use a combination switch ? (two switches on the same yoke)

Extend the stranded about an 1/8" past the solid when entering the wire nut. Biggest mistake is using too big of a wire nut.

crescere · 08-17-2012, 11:09 AM

I do want the fan and light to word separate. I was thinking of running one 3 wire cable back to switches or two separate lines, one to each switch.

To connect stranded wire do I just rely on the wire nut?

Stubbie · 08-17-2012, 11:30 AM

Quote:

Originally Posted by crescere

I do want the fan and light to word separate. I was thinking of running one 3 wire cable back to switches or two separate lines, one to each switch.

To connect stranded wire do I just rely on the wire nut?

Just run a 3 wire cable to the switch box from the existing light fixture. You do this because there is no neutral carried to the switch box and it really is all you need . .

then as said earlier a two wire cable from the light fixture to the fan. You will use the red wire in the 3 wire cable to switch the fan, the black to switch the light, white to get power to the switch box (mark it black on both ends) and bare for ground. The red will connect to the black of the two wire plus ground cable you ran to the fan. Make sure you maintain the same wire size as the power wires. The white wire (power) in the switch box will need two pigtails to get power to the two switches.

Wire nuts are all you need.

This is your alternate method. I have the fan and light reversed but you can see what is going on.

crescere · 08-17-2012, 12:57 PM

Wow. Thanks Stubie. That really helps.