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I'm remodeling an older bathroom. I would like to replace a combination switch/receptacle with two separate light switches and a receptacle in a three-gang box.

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The white and black wires on the power feed from the attic are connected to the receptacle/switch combo in the lower left wood box frame in the first picture. The red wire from the same attic power feed is not connected to anything right now.

Thanks very much in advance for any insight.

  • So, the three incoming wires were used for a three-way switch? – Machavity May 8 at 17:27
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    A picture of the box would also help here – Machavity May 8 at 17:27
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    Can you elaborate further on why you are calling it a "three way wire"? Is it because there are 3 conductors, because you know it's used in 3-way switches, or because this one is involved in a 3-way switch? I ask because the latter case makes it a lot more tricky. – Harper May 8 at 17:35
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    Can you post a photo of the inside of the box please? – ThreePhaseEel May 8 at 22:22
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    Correct. It's actually a metal three gang box, not plastic. – Bostonbuff May 10 at 0:00
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Incoming Power

Power comes in currently from a cable that is nutted to another cable in an octagon box. You mentioned a red wire, visible capped in the box. However, it is not clear whether the red wire is in the cable coming from the panel to that box or whether it is in the cable coming from that box to the bathroom switch/receptacle. It doesn't matter much - either way you don't actually need it - but wherever it is, you should make sure it is capped with a wire nut on both ends for safety.

In addition, the power coming in to the switch/receptacle is a black cable. The color has meaning which makes black an unusual choice. Normally it is white for 14-gauge/15 Amp or yellow for 12-gauge/20 Amp. Black is apparently for much heavier wire. That is safe, but you need to make sure that anything you connect to it can handle that size wire. Fortunately, you will be using wire nuts to connect everything, so it shouldn't be a problem. Just "different".

You also need to make sure that ground is connected all the way through - panel->octagon box->new 3-gang box->switches & receptacle & cables up to lights.

The Big Split

You need to get power to three locations: receptacle, switch 1, switch 2. You need to get neutral to three locations: receptacle, light 1, light 2. Use some short pieces of 12-gauge wire (you can pull them out of a chunk of yellow cable) to make pigtails. Three short black pieces wire nutted to the incoming black wire one short white piece to the incoming white wire.

Receptacle - GFCI?

Bathroom receptacles must be GFCI-protected. However, ideally you do not want the lights to be GFCI-protected, so that if the GFCI trips the lights don't go out. If the circuit is already protected by a GFCI breaker in the panel, then you don't have a choice about protecting the lights, but you also don't have to do anything special here and just install a regular duplex receptacle. If the circuit is not already protected by a GFCI breaker in the panel, then install a GFCI duplex receptacle.

Connect one of the black pigtails to the hot screw on the receptacle and the white pigtail to the neutral screw. If you are installing a GFCI here, make sure to use only Line and not Load.

Switches

For each switch, connect a black pigtail to one screw. If they are simple switches, it doesn't matter which screw you use. But if they are smart switches, dimmer switches or timers then check the instructions to see which screw is hot == black pigtail vs. switched hot == black wire on cable to light.

Lights

For each light, run a cable (I'd stick with yellow = 12-gauge) from the 3-gang box to the fixture. In the 3-gang box, connect white to the incoming white (i.e., the same place you added one white pigtail) and black to the remaining/switched hot screw on a switch.

Connect each light fixture to black (switched hot), white (neutral) and ground.

Connect all grounds together, and you should be all set.

Testing

In addition to testing each switch/light, check the GFCI (if you installed one) using the TEST button. If it doesn't power up at all or RESET doesn't work after pressing TEST then you may have something wired incorrectly.

  • Just awesome Manassehkatz! Two questions after reading your thorough analysis and recommendation. The lone red wire in the octogon box comes is part of the power feed attached to the ceiling/fan unit. I just leave that capped? Should I replace the plain-vanilla 15 and 20 amp circuit breakers for the bathroom in my main box with GFCI circuit breakers? Thanks again for your expertise and patience. – Bostonbuff May 10 at 2:06
  • As far as the red wire: "ceiling/fan unit"? Is that in the bathroom? Is that one of the devices that will be switched with one of the new switches? Or is it someplace else but sharing the power feed? As far as 15A & 20A circuit breakers: From the original question, it sounded like this is 1 circuit. If it is 2 circuits then this is more complicated. But if you have one circuit for "all this stuff" and another for "existing receptacles elsewhere in the bathroom" then I would use GFCI/receptacle rather than breaker. Main reason is that it is easier to reset. Second is lights as noted. – manassehkatz May 10 at 2:09
  • Yes the ceiling fan/light is in this bathroom. There is just one dedicated line which runs from the main box to the fan/light unit to the octogon box that feeds my new outlet/two separate light combo. I'll go with your suggestion and use individual GFCI receptacles. – Bostonbuff May 10 at 2:21
  • What switch controls the existing fan/light unit? Is that part of the "old switch being removed" and/or "one of the two switches being added"? Or is that switch separate and just happens to be part of the same circuit? – manassehkatz May 10 at 2:27
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    Number three. The fan/light unit has a separate switch that just happens to be part of the same circuit. – Bostonbuff May 10 at 2:30

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