Bathroom Light and Fan

[PastorPaul]

Our soon to be new home has a light and fan in the 1/2 bath in the master bedroom (We're talking a 1/2 bath so small that you have to step outside to change your mind). I am going from memory, so please forgive my inability to give detail.

When you turn the light switch on, it also activated the fan. Mary would like that feature deactivated so you don't have the noise of the fan when you tinkle during the time the stars twinkle. She's concerned about the one using the bathroom waking the one who is still sleeping.

Here's where the memory problem comes in: I don't know if it is a light/fan combination, or two separate units, so that will actually determine what can be done. If it is a combination unit, I can just open it up and separate the fan wires from the light wires and install a separate fan switch.

If they are separate units and there are two separate sets of wire going up from the switch, I can just replace the current switch a larger box and have two separate switches (You will see why I can't just use a double switch in a moment).

Now here is the problem. Mary would also like to have the light on a dimmer switch, so the light won't wake up the sleeper either. If the fan and light are wired in such a way that my only solution to control the fan is to install a switch directly on the fan, can I do this without affecting the dimmer switch? What I am figuring, just off the top of my head, is that if the fan is off it shouldn't affect the dimmer switch at all; but if we have the fan on, the dimmer switch has to be on full or something is going to get damaged. Am I correct, or not?

If they are not wired separately, ideally I would like to run the fan wires separately, but I don't know if that will work without tearing out part of the wall or ceiling. I won't know until I actually get into the house and take thing apart.

How about some suggestions or advice.

Pastor Paul

"If they don't have woodworking in heaven, I ain't going!!!"

[Grandad]

>When you turn the light switch on, it also activated the
>fan. Mary would like that feature deactivated so you don't
>have the noise of the fan when you tinkle during the time
>the stars twinkle. She's concerned about the one using the
>bathroom waking the one who is still sleeping.

You may not be able to do this. Some cheaper units made by Braun, one of the largest manufacturers, can't be wired this way without taking the unit apart, and even then I am not sure that it can be done. As long as the unit is designed for it, and the installer was just cheap, no big deal.

>Now here is the problem. Mary would also like to have the
>light on a dimmer switch, so the light won't wake up the
>sleeper either. If the fan and light are wired in such a
>way that my only solution to control the fan is to install a
>switch directly on the fan, can I do this without affecting
>the dimmer switch? What I am figuring, just off the top of
>my head, is that if the fan is off it shouldn't affect the
>dimmer switch at all; but if we have the fan on, the dimmer
>switch has to be on full or something is going to get
>damaged. Am I correct, or not?

Yes, motors can be damaged if you do this. Dimmers are never to be used on fans, just like you can't on a ceiling fan.

>How about some suggestions or advice.

Before doing anything, turn the light on, turn off the breaker, then make sure the light is off. Make sure the light is on before tripping the breaker on the off chance that the light blows at the same time you turn the WRONG breaker off...

First, take the switch cover off. Look inside and determine the type of wiring. Romex or BX will be more difficult, while conduit is easy. Also, look at the fan by taking the cover down. The part that covers the bulb will certainly come down, and you should be able to figure out how to view the insides then. If you understand wiring, and I think you do, then you should be ready to go. If not, tell us what color wires are where, and how many pipes go from/to each box. When I did some wiring in my basement I had to actually draw out every single wire, because the morons who did it had no clue what they were doing. They ran one wire 90 feet around the staircase rather than use the open pipe that went directly where they needed - 10 feet away! So much for union electricians! Being in a union didn't make them any smarter, just more dangerous. Fortunately most electricians know what they are doing. Still, you could end up with more wires than you can easily identify, and then I recommend you figure all of them out before you start.

[TDHofstetter]

You can in fact buy, in the "lamp parts" section of your favorite hardware store, a pullchain switch just like the ones that used to dangle from every light fixture in all our houses once upon a time. The difference here is that these switches are "universal" in that they'll fit x size hole drilled in almost any material (think fan housing here) and have two pigtail wires sticking out the back which could be used to interrupt the "hot" wire leading to the fan. Bingo - instant fan-isolation switch.

The issue with running a fan on a dimmer switch is a little different with some kinds of fan motors - typically, such a motor as would be used for a bathroom vent would be of the "shaded-pole" type... exactly identical to that used in your old phonograph. Unlike an induction motor, a shaded-pole motor isn't likely to be hurt much if you operate it on a dimmer as long as you don't run for it a long time at diminished speed. SP motors also don't draw squat for power, so the fan isn't likely to hurt the dimmer. Better check to be sure, though - if the fan's bigger than I think it is, it may be run by a squirrel-cage motor or even a little induction motor. Better check for current draw, too. Should be a little "ratings" plate someplace on or inside the fan housing.

-- Tim --


Eschew obfuscation.