3-way switches on ceiling fans

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  #1  
Old 07-24-02, 01:22 PM
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spurling316
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Question 3-way switches on ceiling fans

Could you please give me some information on how to wire
a ceiling fan with a light fixture using 3-way switches so the
fan can be controled from 2 locations. Cannot find any information on this subject. Thanks for any assistance you can provide.


Steve.
 
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  #2  
Old 07-24-02, 01:33 PM
J
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It would be useful to know what you are starting with. And there are more than one way to do this. And we don't know how you want to control your light. And I don't know whether this is a 20-amp or 15-amp circuit. And I don't know what brand of fan you have.

Let me assume that this is a brand new installation with no wiring in place now (seems unlikely, but I'll assume that anyway since I can't reasonably assume something else). And let me assume that you are going to use the pull chain to turn on the light, and that the light will only work when the wall switch is on (not a really good assumption, but ...).

So run 12/2 from the breaker to the first switch, 12/3 from the first switch to the second switch, and 12/2 from the second switch to the ceiling. At the ceiling, connect black to both black and blue from the fan, white to white. At each switch, connect the 12/2 black to the common, and the 12/3 red and black to the travelers, and connect white to white. That'll do it.

What assumptions did I make wrong?
 
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Old 07-24-02, 05:54 PM
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terrywouldbe
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alternate method?

John,

Seems that your cable runs are the less expensive method than the the one which I used, as you are using less 12-3 than what I did. Though in both of your switch boxes, there are two cables, and mine has only one cable in the the second switch box.

I wonder, however, if I'm ok with code, since my method involved connecting a white to a black in the ceiling (or, is this simply what is called a switch loop)?

I ran the cable and made the connections as follows:

12-2 from Panel to sw1;
12-3 from sw1 to ceiling;
12-3 from ceiling to sw2;

Connections:
sw1
12-2 white (neutral) to 12-3 white;
12-2 Black (Hot) to common terminal;
red and black from 12-3 to traveler terminals.

Ceiling
12-3 Black from sw1 to 12-3 White of sw2 (white taped black for Hot indication);
12-3 white from sw1 to white of FAN;
12-3 Black from sw2 to both the Blue and Black of FAN;
Red to Red.

sw2 (One 12-3 Cable enters)
Black to common;
Red and White to travelers.
White wire taped black to indicate hot.

Everything works, but am I ok with NEC? This was new construction.

Thanks,
-Terry
 
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Old 07-24-02, 06:49 PM
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There are many code-compliant ways to wire a 3-way switch setup. That's what makes them so confusing for so many people. The best way for a particular situation depends on the exact topology of the room, and other power needs. It's not a one-size-fits-all. However, the way I described is by far my preferred way, even if it might use more wire in some situations. My way doesn't use any switch loops, and switch loops always confuse people.

Terry, your wiring is safe, code-compliant, and common. Don't lose any sleep over it. Sometime in the future, however, you or the next homeowner will take down your fan to replace it. All the wires will be disconnected without paying attention to how it was connected. Then that person will be posting back ten years from now wondering how to hook it back up.

Note that with my way, there is only one wire of each color in the ceiling, and there's almost no way to mess this up when replacing the ceiling fixture.
 
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Old 07-25-02, 12:16 AM
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terrywouldbe
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agreed

John,

Well, your way absolutely is far easier to remember than mine: much more to wonder about with my method.

Three way switching methods, the way I have been doing it, have always been difficult to remember - have always had to go back to the diagrams in books in order to remember. My wiring jobs are very sporadic, and if one doesn't do this everyday, well, one forgets.

At any rate, as always, thank you for your input.

now, I have one follow up: Regarding your method:

The 12-3 between switches: would this be one (1) uninterrupted/uncut/unspliced cable running the entire distance between the two switches? That is; I see it as having no sheathing trimmed from the cable as it runs through the ceiling box.

I'm wondering about the physical difficulty of running a long (say 20' piece of) unsheathed cable through the small knockouts of the outlet box. This is why I have always cut, and ran two separate cables: one through each of the knockouts in the ceiling box, and then spliced the two with wire nuts.

Please, this may sound silly, but of course you know that I am inexperienced in all this - else I wouldn't be asking the silly questions. Your time in answering is greatly appreciated.

-Terry
 
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Old 07-25-02, 07:11 AM
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The 12-3 between switches: would this be one (1) uninterrupted/uncut/unspliced cable running the entire distance between the two switches?
Normally, yes. If doesn't absolutely have to be uncut and unspliced, but there is no reason to splice it. If you did splice it, you can't put anything useful in that junction box, and you'd need to keep it permanently accessible.

I'm wondering about the physical difficulty of running a long (say 20' piece of) unsheathed cable through the small knockouts of the outlet box.
There's no need to. Run the cable from the first switch box to the second switch box, but don't insert the cable into either box until you've run the whole cable and cut to length. Then you just need to insert the end of each cable into each box. There's too much chance of cable damage if you start the feed from inside the first box.
 
  #7  
Old 07-25-02, 03:56 PM
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spurling316
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3-way switches to ceiling fans

Thanks for the information,however let me give you more information on how I want the fan to work. I would like
the fan and light to work off separate switches from two different
locations in the room. Two switches in the first location and
two switches in the second location. I'm using a 20-amp circuit
and would like to run power into the two switches at the first
location to the fixture then from the fixture to the two switches
at the second location if this is possible.


Thanks again Steve
 
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Old 07-25-02, 09:09 PM
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This would be simpler if you ran power to switch to switch to fan. But I'll give you the instructions you want.

Run unswitched power on 12/2 to the first switch box. Call this cable "P". Run one 12/3 cable (called "X") and one 12/2 cable (called "T") from the first switch box to the fan. Run two 12/3 cables ("A" and "B") from the fan to the second switch. You can see already that you have four cables at the ceiling -- your ceiling box needs to be at least 27 cubic inches (I hope you can find a fan-rated box that big).

At the first switch box, you will have two 3-way switches "S1" and "S2" in a double-gang box of at least 27 cubic inches. Make the following connections:
  • Pb to two pigtails. One pigtail goes to S1 common, and one pigtail goes to S2 common.
  • Pw to Xw.
  • Xr and Xb to the two traveler screws on S1.
  • Tb and Tw (marked black) to the two traveler screws on S2.
At the second switch box, you have two switches "S3" and "S4" in a double-gang box of at least 24.745 cubic inches:
  • Ar and Aw (marked black) to the two travelers on S3.
  • Br and Bw (marked black) to the two traveler screws on S4.
  • Ab to the common screw on S3.
  • Bb to the common screw on S4.
At the ceiling, things get fun. As I said, the fan-rated box needs to be at least 27 cubic inches.
  • Xw to the fan's white wire.
  • Ab to the fan motor's hot wire (usually black).
  • Bb to the fan's light hot wire (usually blue or black with a white stripe).
  • Tb to Br.
  • Tw (marked black) to Bw (also marked black).
  • Xb to Aw (marked black).
  • Xr to Ar.
Of course, interconnect all grounding wires and screws -- pigtails will be required at the switches.

Now S1 and S2 will control the fan motor, and S3 and S4 will control the fan light.
 
  #9  
Old 07-28-02, 12:51 PM
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spurling316
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3-way switches to ceiling fans

Thanks for all your help! I hooked everything up just as your instructions said and it works perfect.
 
  #10  
Old 07-28-02, 01:37 PM
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terrywouldbe said:
The 12-3 between switches: would this be one (1) uninterrupted/uncut/unspliced cable running the entire distance between the two switches? That is; I see it as having no sheathing trimmed from the cable as it runs through the ceiling box.
The 12-3 between switches does not run through the ceiling box, just from one switch box to the other.
 
  #11  
Old 07-28-02, 09:29 PM
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terrywouldbe
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much clearer!

mike,

Thank you!

I was thinking that the 12/3 between switches had to make a direct connection somehow at the light, but I see that's not necessary-no need to run it through the ceiling box, therefore.

This is so much simpler a method for understanding and remembering three-way switching than what the DIY books I have read show. I suppose there are pros and cons to both methods, but I wonder what they are?

Thanks to both John and mike!

-Terry
 
  #12  
Old 07-29-02, 08:56 AM
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Thanks for catching that Mike. I had earlier missed that "through the ceiling box" phrase.
 
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