Wiring ceiling fan with 3 wires (no light) to a 3 way light switch


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Old 07-28-21, 11:51 AM
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Wiring ceiling fan with 3 wires (no light) to a 3 way light switch

I have a new fan (no light) with 3 wires, black white and ground. I’m splicing into an existing 3 way switch for can lights, so there are 4 wires, black, red, ground and white. The switch will control both the cans and the fan, but the cans are smart bulbs so switch will just always be on, and fan will be controlled with remote.

Do I connect BOTH the black and red from the 3 way switch to the black on the fan? Or only connect the black and cap the red? I know ground to ground and white to white.

I’ve tried googling but only found every other variation except this one. Thanks!!
 
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Old 07-28-21, 12:03 PM
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Welcome to the forums.

When doing any type of wiring..... the ground is not discussed. It is understood and just gets connected.

Are you saying that you have red, white and black at the fan box ?
Was anything already installed there ?
 
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Old 07-28-21, 12:23 PM
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Thanks for the welcome and the reply. There is nothing there now. I have attic access to the install site and am installing a ceiling fan rated box on the stud. I am splicing into the wiring for two existing can lights. They are on a 3 way switch to 2 single plate switches in different rooms. We currently keep the switch on at all times because the bulbs are smart bulbs and on a timed program.

Good to know about ground. Figured if I didn’t mention it someone would say ‘there’s no ground?!’ The existing wiring has red, black, white. The fan only has black and white. So do I cap the red or put both the red and black from the switch to the black on the fan? I’m not totally clear on how the 3 way switches work and am worried about not completing the circuit.

thanks for any tips!
 
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Old 07-28-21, 12:33 PM
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So you are cutting into the middle of a three way switch line ?
That doesn't usually work well.

Don't those three way switches currently operate something ?
 
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Old 07-28-21, 12:38 PM
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3 way switches are wired in pairs. Between the two 3 way switches are three wires. Two wires are the transfer connections and the third wire is common (power source enters one of the 3 way switch boxes) or switched hot ((power source enters one of the can light boxes). There should only be 2 wires between the can lights and first 3 way switch. What arrangement do you have?
 
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Old 07-28-21, 01:03 PM
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Now I feel silly. I hadn’t cut into the wires yet, but knew there were the three coming off the three way switch.

However, I am going to splice into the wire running between the cans, which I’m pretty sure will only be 2 as someone mentioned, so shouldn’t be an issue.

I was posting this today because I plan on doing the work early tomorrow morning before it’s over 100 degrees up in the attic. I tend to overthink things.

thanks for the feedback!
 
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Old 07-28-21, 01:29 PM
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Be aware that cutting the middle of a cable does not usually leave you enough cable to bring into the box. It often requires two boxes and new section cable between them. You must have at least 6 inches from each cable coming into the box. That means the cable you are cutting must have at least 12 inches of slack.
It might be a better option to run a cable from one of the existing light fixtures.
 
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Old 07-28-21, 01:48 PM
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There is actually a bit of slack, but running from the secondary light probably makes more sense than splicing and adding a junction box. Thanks for the suggestion!
 
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Old 07-28-21, 07:04 PM
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There is actually a bit of slack, but running from the secondary light probably makes more sense than splicing and adding a junction box.
Yes it makes the most sense the proper wiring is there..... switched hot and neutral.

You wouldn't know what you'd find when you cut in to the three wire cable but more than likely it would not have been what you needed. There are two hot wires that alternate and one neutral. Pretty hard to connect to.
 
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Old 08-12-21, 10:44 AM
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You have a 3 wire cable (red, black,white, ground) loose in the ceiling going over and down to one of the 3 way switches. You may not cut it and hook up a light fixture or fan at the cut point.
 
 

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