Wiring Bathroom switches

pcthompsonAugust 9, 2012

Description of Photo: This is a basement bathroom. The pic is of an electrical wall box that has room for two switches. I believe one switch is for a light above the vanity, and the other for a ceiling light with fan. This is a guess because there is no junction box above the vanity and there is no ductwork to vent the fan. There is a white wire (with a black, white, and ground) that runs to the ceiling for a ceiling junction box, which I will need to install.

I installed a GFCI Outlet and it works fine. I am a little worried about cutting a hole above the vanity and not finding a wire. I am not sure what to expect. I just want to get some light in the bathroom, so we can use the sink and toilet.

There are three black wires and a red wire. Do I use two single pole switches? Why is there a red wire since it will not function as a three way switch?

The bathroom was framed with drywall and stub plumbing when we bought the house. There is do drop ceiling yet.

Thanks in advance for any guidance.

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Ron Natalie

We have no clairvoyance on to how this was wired. How did you get to this state? Was there a switch that was removed or are you coming upon something that was roughed in by someone else.

What do you mean you installed a GFCI there? This looks like #14 wiring and you can't legally connect a bathroom receptacle to a 15A circuit.

The biggest clue would be to remove the fan/light and see what wires are running to them (and hope nobody installed a hidden junction somewhere and flipped the wiring around).

Many bathroom fans have both a fan and light so they use the extra wire in the 14-3 is used to run the fan while the other is used for the light.

    Bookmark   August 9, 2012 at 11:02AM
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Additional information, as Ron mentioned, would be useful.

My initial thought and absent any other information it appears that power comes in on wires 1 and 2. Then goes out to the vanity and light/fan on wires 3 and 4.

It does appear that you have some extra neutrals in there as well. Are there other wires in the box that aren't shown in the picture?

As for light above the vanity, I assume you have access to the joist space above the bathroom? You should see a cable or conduit going down the wall through the top plate.

I'm hoping there's a junction box above the vanity. It should be mounted on the side of a stud, so that may give you some clue as to its location. If the box was installed properly, there may be slight bow in the drywall which could be another clue. The last option is to make a small hole in the drywall and go in with a L shaped piece of wire and feel around. You may need to repeat that a couple of times.

You also said something about the fan not being vented. Get that done too! Dumping hot, moist air into the joist space is not a good thing.

    Bookmark   August 9, 2012 at 11:56AM
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Here is my best guess.

#1- black wire connected to hot in/hot out (feed for both switches)
#2- black (switch leg) to your vanity light
#3&4- 3wire cable (switch legs) to fan/light combo, red to light, black to fan (personal preference)

If not, that's what it should have been.

    Bookmark   August 9, 2012 at 9:28PM
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