Wiring a bathroom fan

turfserfMarch 9, 2014

I am planning to put an exhaust fan in a second-floor bath with attic access. There is a light switch in place in the bathroom, and I will replace it with a two-gang box, adding a timer for the fan that requires a neutral.

My first instinct would be to steal power for the fan where it comes into the bathroom light switch and run a switch leg up to the fan in the attic. BUT, the house was built in 1952, and I don't see a ground wire in the existing box. In the last couple of years we had an electrician wire new ceiling lights and air-conditioner outlets on the second floor, and all of that power runs through the attic. I expect that this new work has a ground wire, so I'd like to splice into one of these lines to power the fan, and run a switch leg (with the required neutral) down to the two-box in the bathroom.

Does this sound reasonable? Thanks for the help.


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Ron Natalie

You're free to run the fan from a general lighting circuit. Barring one of the units that has a heater integral to it, it ought not to cause a load issue. Once you've tapped into the other lighting circuit, you can either use a switch leg or just run a feed down to the switch box (in addition to running to the fan).

The only issue you need to check is if the fan instructions requires a GFCI (normally only if they're installed within the shower area). If so, you'll need to find a way to protect it appropriately.

    Bookmark   March 9, 2014 at 11:15PM
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