Replace single toggle with split switch for light/fan combo

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  #1  
Old 11-10-05, 02:37 PM
Cowper
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Replace single toggle with split switch for light/fan combo

I would like to replace the single toggle switch that controls my bathroom light and fan with a double toggle switch. I want to be able to control both fixtures separately, as it is they are wired in tandem.

The original setup had three white wires spliced together. The remaining three black wires were attached to the single toggle. One of them was pushed through the hole on the back of the switch.

I bought dual toggle switch which has a ground, two common poles, and an A1 and B1 pole. The common poles come attached by a fin but can be separated.

Anyone know how to do this!

Thanks!

Geoff
 
  #2  
Old 11-10-05, 06:38 PM
J
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It probably cannot be done with the existing wiring. But there's a slim chance that it might.

Are your light and fan in the same fixture, or in separate fixtures?

Do you own any electrical test equipment? If not, I suggest you spend $2 at your home center on a neon circuit tester.

Is the old switch still in place and still wired as original? If not, did you record exactly where on the old switch each of the three black wires was connected?
 
  #3  
Old 11-11-05, 04:12 PM
Cowper
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John,

The two fixtures are indeed seperate. I did note how the three, otherwise unmaked, black wires were attached to the original switch. Two were attached to the two poles, the third, pushed in through the hole behind the bottom pole on the back of the switch.

I own a circuit tester (or rather...a device with a lamp and two leads for indicating a "hot circuit) I also have a digital multimeter (which may be useless for these purposes).

The double toggle switch I bought has two common poles which can be joined or separated by a "fin" and two other, unjoined poles labled A1 and B1. I assume the A and B indicating different circuits. The device, of course, also has a green ground pole.

Any light you can shed would be great!

-Geoff
 
  #4  
Old 11-11-05, 04:23 PM
J
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Do you know which one of the three black wires was poked into the bottom hole, and which one of the three black wires was attached to the bottom screw?
 
  #5  
Old 11-12-05, 10:40 AM
Cowper
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Absolutely! I know where all of them were.

-Geoff
 
  #6  
Old 11-12-05, 03:59 PM
J
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Okay. Now we are going to do some experimenting.

You have one of the following two situations, and the objective is to figure out which one you have. The three black/white pairs are either:
  1. (A) unswitched incoming power, (B) switched power to the light, and (C) switched power to the fan.
  2. (A) unswitched incoming power, (B) outgoing unswitched power, and (C) switched power to both the fan and light.
You're hoping that you have the first situation, but to be honest, the second situation is far more common.

Here's the first experiment:
  • Shut off the breaker.
  • Remove the switch.
  • Use a wire nut to connect the black wire which was poked in the bottom hole to the wire connected to the top screw.
  • Cap off the remaining black wire with a wire nut (the one which was on the bottom screw).
  • Chase the kids and dogs from the room, and turn the breaker back on.
Note whether the light or fan or both are on with the first experiment.

Here's the second experiment:
  • Shut off the breaker again.
  • Use a wire nut to connect the black wire which was connected to the bottom screw to the wire connected to the top screw.
  • Cap off the remaining black wire with a wire nut (the one which was poked into the bottom hole).
  • Chase the kids and dogs from the room, and turn the breaker back on.
Note whether the light or fan or both are on with the second experiment.

Here are the possible outcomes:
  1. Fan and light both on with one of the experiments. Neither on with the other experiment.
  2. One of them on with experiment one, and the other on with experiment two.
Post back with which result you got. If you had the first outcome, then you are going to need to run more cable inside the wall to accomplish what you want. We can help you with that. If you had the second outcome, then you can accomplish what you want with the existing wires. We can help with that too.
 
  #7  
Old 11-12-05, 05:25 PM
Cowper
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John,

So, sadly, I got the second result. The power to both fixtures comes on with the first combination, and not at all with the second (being the two wires from each pole)

Guess that means I have to run a wire? Geez - I was hoping to just replace the switch!

-Geoff
 
  #8  
Old 11-12-05, 07:16 PM
J
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Do you have an accessible attic above this room?

Even if you need to do a bit of drywall repair, it's not hard. Maybe this bathroom needed repainting anyway?
 
  #9  
Old 11-13-05, 12:26 AM
Cowper
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No attic, but couldn't I use the exisiting wires to pull a new one through? Otherwise it may involve a few holes here and there. . . . .


What wires do I have to lay out?

-Geoff
 
  #10  
Old 11-13-05, 09:55 AM
J
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No, you're not going to be able to use the existing wiring to pull new, unless your wiring is in conduit. The existing cable will be stapled.

Here are your main two options. I'm going to conservatively assume a 20-amp circuit and therefore specify 12-gauge wire, but you can use 14-gauge wire if the breaker is a 15-amp breaker.
  1. Run a new 12/2 cable from the switch box to either the light or the fan. This is going to make the switch box really crowded, so it's probably not the best solution unless you replace the single-gang switch box with a double-gang box.
  2. Replace the 12/2 between the switch and the fan or light with 12/3. This would require you to figure out whether the existing 12/2 from the switch goes to the light or to the fan. This can be done with more electrical tests before opening up the wall.
Small holes in the drywall are easier to repair than big holes, but small holes may make the job difficult. Big holes are as easy to repair as medium-sized holes. You may find it easier to remove enough drywall to make the job easy, rather than trying to minimize the damage. Read a good book on drywalling (Myron Ferguson is the leading expert author) before doing the repair. To get an invisible drywall repair, take your time, make sure all the drywall edges are well supported, use three feathered coats of joint compound with tape, treat it as an art project, and don't cut corners. If you learn to do drywalling well, it's a skill that will be very useful over and over again.
 
  #11  
Old 11-13-05, 10:43 AM
Cowper
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Great! Thanks for the help John. I'm going to read up a little on drywalling first - which is fine with me because as you said - it's something that would come in handy big time down the road - like when I decide to renovate the entire house.

Cheers,

Geoff
 
 

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