I have a vanity light. Power comes into the light. A wire runs to the switch. I am planning on installing a bath fan that has fan/light/nightlight. The existing switch is mounted in a 1 gang box in beadboard. I would like to avoid cutting in a 2 gang box. I also have a 12-2wg romex unused running from the panel to the attic where the fan is going. I have a 1 gang stacked switch for fan/light/nightlight. I would like to just run a switch leg to the same box and switch both lights on this switch. Does the two power sources make this immpossible? Last resort, can I use the same swich with one light/the other light/ fan and eliminate the nightlight?
Electrical – Wiring bath lights that have two power sources
electrical
Related Solutions
You either have to replace the Vent wire with 14-3 AWG wire, or run a second 14-2 wire from the existing light to the vent. Assuming both switch circuits are from the same feed, you only need 3 wires to the vent. All the whites get tied to the white neutral of the feed. You could use the black (or Red) to go to the light - fan, and the Red (or black) to go to the night light.
This quick schem shows the connection with adding one 14-2 cable from the existing light to the Vent.
M-L-N can be switched around, depending on which functions go with the shared switch. I assumed the night light gets its own switch.
The following diagram should help you to visualize how to wire up the three switches. In your case you may have 12 AWG wire due to the 20A circuit. Also you will substitute one of the lights with the blower fan motor connection.
Picture Credit: Taken from this web page.
Related Topic
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Best Answer
No to Q1, switching both lights, unless you get the same power that the existing light switches to be in parallel with the fan light. That would mean running the same gauge 12 or 14 -2 (hot, neutral and ground ) to the fan light from the overhead light.
Combining circuits risks having 240 VAC across your fixtures. It can be done, if neutrals and ungrounded (hots) are kept separate (from each other and not connected through a device section to another.
Maybe to question 2, if you mean using the one (original power source) to switch fan, light, fanlight together. (this assumes the added device wattage doesn't exceed the wire capacity.
You would be better served by biting-the-bullet and put in a new switch box and use the separate power available and get all 3 functions separately Am I guessing correctly that the bath outlet is on the same circuit as the light and they are 14 gauge?? One hairdryer-light-fan-fan light will likely overdraw a 15A breaker