View Full Version : Bathroom Vent Wiring

06-16-2007, 11:37 AM

I am installing a bathroom vent/light unit.

Currently there is only one light abov the vanity. This light is controlled by a switch when you walk into the bathroom. I want to be sure the fan is being used when the bathroom is in use (rental property where the if the tenants had the option they would choose not to run the fan to save money), therefore I would like only ONE switch in the bathroom, so the vent/light will go on when the light above the vanity goes on.
Is it possible to do this? And how would it be wired?


06-16-2007, 12:33 PM
Either feed the fan from the vanity light or tie it to the load side of the switch. The problem is getting the wire to one or the other without damaging the wall finish.

06-16-2007, 12:49 PM
Your problem is very simple actually. The fixture comes with separate hot wires to the fan and the light and a shared neutral. Just connect both the fan and the light hots together and then connect as if you were replacing a light fixture.

You might want to read about the problems which occur from venting these into an attic instead of going out to the soffit.

06-16-2007, 06:31 PM
Thanks for the replys,

As far as going through the roof or the soffit, I have been doing some research.
Here's what I found: The cons of going through the roof are;
1. a potental roof leak (which will be avoided when the hole and cap are done properly)
2. Condensation coming down the exhaust pipe into the fan unit (which can be prevented by insulating the exhaust pipe)

The pros of going through the roof are;
1. The warm moist air naturally rises, so you have the laws of physics on your side, when you direct the air out of your house above the roof.

The cons of going through the soffit are;
1. The warm moist air can damage the soffit material

If anybody has any more insight on the roof vs. soffit exit location for bathroom vent fans please let me know. I am about to begin this project.


06-17-2007, 05:04 PM
Both hots for the light & fan are how we have ours wired. That was because I did not want to pull wire in the middle of Summer at the time. It was bad enough to have to put a fan up in the attic with me to keep cool.

As for the vent, the air has to go outside, due to letting it stay in the attic is not only bad, but also, it is better for the attic. The vents are the same that are used for Dryers, with automatic closing flaps that keep the air from coming back when it is not in operation.