I am putting a basement bath in and I need help. I will be adding a new 20 amp circuit for the single pole outlet. Also, a 20 amp line for a 3 switch box. Switch #1 is for the vanity light, #2 is for the exhaust fan light and #3 is for the exhaust fan.

I would appreciate a drawing showing from the 3 gang box the wiring of the circuit.


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.

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Picture Credit: Taken from this web page.

  • Do I have to stay with 12/2 wire for the switch and fixture connections since I have a 12/2 (20amp) A.F.C.I. breaker line as the power line coming into the 3 gang box ? – Larry Apr 15 '13 at 11:04
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    You can use 12/3 to feed the exhaust fan, since you'll share the neutral at the fan. Black will be switched hot for light, Red switched hot for the fan. – Tester101 Apr 15 '13 at 11:31
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    @Larry - If you bring 12/2 wire into the box as the power feed you should continue the use of 12AWG wire to all branches off the feed circuit. – Michael Karas Apr 15 '13 at 13:40
  • @MichaelKaras But the fixture wires are only 14 AWG, would you have to rewire the fixtures if you're using 20A and 12 AWG? – Tester101 Apr 15 '13 at 17:37
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    @Tester101 - The need to carry the 12 AWG wire through the ganged switch box is because the circuit is circuit breakered at 20A. If the wiring pigtails on the blower fixture are only 14 AWG then I would say to just connect them to the 12AWG wire fed up to the blower electrical enclosure. – Michael Karas Apr 15 '13 at 18:33

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