home wiring question for bathroom fan
 

Our home was built in 1986 and has two bathrooms on the main floor. Both bathrooms do not have exhaust fans which I want to correct. I guess because they each have a window it was not code back then. Anyway both bathrooms have a single pole switch that operates a light fixture. I really don't want to tear up the walls to add a duplex box. Can a switch like this be used instead ? If it can all I have to do is fish the wires from the exhaust fans down from the attic into the existing boxes. Thoughts ?

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The fan will come on with the light?

How much light load do you have in the rooms? (watts)

How big of a fan? (amps)

Why not just run the fan off the same circuit as the lights? May not meet local code?

Tearing up the wall shouldn't be a big deal in a drywall house and not necessary. Just cut the board to the size of a two gang box and screw it off to the stud. Careful cutting (and removal of the single) will cause no extra work and you will be able to control lights and fan individually.

I've done similar things previously - and this is how I handled it.

Verify the existing wiring path within the switch box. If you've got two cables - 1 for infeed and 1 for outfeed to the light - you are good to go. For each bathroom, buy a new switch, new double switch cover plate, and a double box for old work - the style with two screws on adjacent corners that tighten up against sheetrock that is already in place. Cut the breaker supplying power to the switch and remove existing switch from the box. Straighten out existing wiring best you can, then take a sawzall and cut along the stud side of the existing box - to cut through the nails holding it in place. Slide the box out of the wall. Mark and cut sheetrock for the newer double box. Fish the new wire for the bath fan from the attic through the now increased size hole. Feed new wire and previous wiring though back side of new box - insert box and tighten screws. Hook up wiring to new and old switch.

I've done this several times - hardest part is fishing new cable from the attic. Make sure you feed it through on the correct side of the wall stud.

That is a twin single pole switch so yes it would work to control fan & light separately in a single switch box. As long as you know what you are doing, it would be an easy install - although fishing wires often doesn't go as planned.

Ian

That switch is fine, now you need creative wiring. Not too hard to do really.

Be mindful of box fill especially if there is going to be any 12 ga. wiring.

Take a look at this chart.

If you're running wire through the attic joists, putting a board across the top of the wires will keep someone from stepping on them later.

The Old work boxes attach to drywall and float. New work to studs and are stronger. (edit: switched these by mistake)

IMO in the scope of this job, it would be better to just cut out a large section, put in the double box, trim the cutout piece for the new box, and replace. Doubling up 2x4 on the studs and/or using overlapping 1x8/10 at the edges will hold the drywall tight and easily patchable.

Fans should vent to outside not attic, of course.
Keep it away from windows and eves if possible. There may be a clearance code for that. Drill a hole in the center then use a hole saw from the outside. A boxed drop-down vent run might be necessary.

Check for existing structural beams or wiring in the way before starting.
Drywall is easy to fix comparatively to other problems.

^^^^I agree with that. I find that removing the existing box gives ms a lot more access for fishing.
There is another obscure code that I learned last year. No screw heads allowed exposed in the box unless they are within 1/4" of the corners. And then they have to be as flush as possible. No exposed threads anywhere inside a box.

You could use a length of jack chain to drop down from the attic to pull your new switch leg for your fan.

I have the same switch in my upstairs bathroom. I've never had an issue.

My thought is how are you going to get the wire into the old box without messing up the drywall? You'll have to get a knockout out of the box somehow, fish the wire through the hole, and clamp it to the box - all from inside a 4" box that already has at least one wire in it. Sounds pretty challenging.
As much as I hate drywall work, I agree with everyone here who says cut a decent size hole in the drywall so you have some room to work and put in a double box.