Need a master bedroom bathroom fan to control humidity. New install and plan to have a timer vs a switch. Have one light fixture on wall over bathroom medicine cabinet. This fixture is controlled by a switch located just outside of the bathroom and there is 1 black wire in and then 1 out, so I suspect power goes to light first.

Also have one wall plug. I have a bathroom just below on the first floor with a GFI plug. I think the GFI plug there is connected to the MB bathroom and then goes on to the kids BR. 1 GFI plug connected to 2 others as a way for the builder to save money I guess.

Plan to install fan in MB bathroom ceiling vented through insulated attic space to soffit. Fan will not have a light.

Key problem for me is where to tap power from. I don't think I can tap from the light fixture and won't adding a run from the GFI circuit interrupt the last receptacle in the chain. Lost! Any suggestions, with diagrams of course? Thanks.

The outlet in the MB proibably is protected by the GFI in the downstairs bath. You could pull power from either the outlet or the light. Probably easier from light. Run 2-conductor cable from light to fan ceiling box. Run 2 conductor cable from ceiling box to switch box. That way you only have to get wires through top plate of walls, not through studs. Only outlets have to be GFI protected.

The outlet in the MB proibably is protected by the GFI in the downstairs bath. You could pull power from either the outlet or the light. Probably easier from light. Run 2-conductor cable from light to fan ceiling box. Run 2 conductor cable from ceiling box to switch box. That way you only have to get wires thru top plate of walls, not thru studs. Only outlets have to be GFI protected.

I assume I can tap into the GFI circuit by running a white wire to the fan and then a black wire to the timer and then to the black or hot side of the outlet. Anything wrong with this plan?

Your bathroom receptacles should be on a circuit with nothing else like they appear to be now. That's what code says. If it were me I'd take power from the lighting fixture.

The hot and neutral must run together in the sheathing. Therefore, you run both hot an neutral from the outlet or the light fixture to the fan in one cable. You then run a cable from the fan to the switch, one wire (the white marked as hot with black tape) takes the power to the switch and the black brings it back to the fan when the switch is on.

psmith1111,

Another suggestion, run from any convienent 120vac power source to the new fan, then

Get an 'occupancy sensor' mount it in the ceiling, wire it back to the fan. The fan will come

On every time someone is in the room. You wanted options right ?