Red wire in home pre-wire for fan.

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  #1  
Old 09-03-06, 09:25 AM
J
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Red wire in home pre-wire for fan.

I am installing a ceiling fan in a new home that has been pre-wired for fan. The pre-wire junction box contains white, black, red and ground wires. One wall switch controls the 110V to the black wire. With the wall switch on, I measure about 40V between the red wire and the white or ground wires. Is the red wire a low-voltage lighting supply?

My fan (a Harbor Breeze builder's series from Lowe's) only has white, black and blue wires, and I am installing a remote control between the fan and the home pre-wire circuit. The remote's connection to home wiring only has black and white wires. I intend to add a standard light kit, designed for this fan, as the final step in my installation.

The red pre-wire seems unnecessary to my installation. Is it OK to just isolate it in the junction box with a wire nut, and leave it alone? What is the red wire intended for?
 
  #2  
Old 09-03-06, 09:42 AM
J
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What you electricain did is common. A three conductor wire was run incase someone wanted to install a fan/light and use an over/under switch to have seperate control.

If your remote will control both the fan and the light, you can just leave the red wire capped off.

You also have other options. You could leave the wall switch control the light, bypass the switch entirely, or several other things.

As for the 40volts. This is most likely what we call a Ghost voltage. It is caused by one wire inducing a voltage into the other. It is not a real voltage in the sence that it does not have the ability to do any work. If you used an analog type meter, wiggie, or lamp type tester it would not be there. Digital meters are not as good for the type of thing you are testing for.
 
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Old 09-03-06, 10:02 AM
J
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Thanks, jwhite. I did in fact measure the 40V with a digital meter, so I guess that explains the ghost measurement. I was not aware of digital meters' greater susceptibility to this phenomenon.

I'm happy with using the wall switch for power to the ceiling fan system and the deluxe remote to control the fan and lights, so capping the red seems like the best option for my application.
 
  #4  
Old 09-03-06, 10:48 AM
J
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One more thing to be sure of is that the ceiling box is fan rated. The cheep plastic, or bakelight boxes will not stand the test of time.

I am not sure how to check to see if the box is fan rated after the box is installed. It may say it stamped into the plastic.

I will research and get back to you, or maybe one of our other members knows the answer and can post it for us.
 
  #5  
Old 09-03-06, 12:41 PM
J
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Thanks for pointing that out, but this is a well-established builder's pre-wire, specifically for ceiling fan in a high-end new home, so I'm not too concerned. The ceiling box appears to wrap around a 2x above the ceiling drywall, and the fan mounting bracket screws directly into the edge of the 2x through the box's molded-in holes. The box does not support the fan; it only encloses the wiring.
 
  #6  
Old 09-03-06, 12:46 PM
J
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COOL I put fan boxes in places all the time even when the current spec does not call for them.. (even on the lower end houses ... )

I am sure you will be fine. I was just covering all the bases. so to speak.
 
  #7  
Old 09-03-06, 05:09 PM
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The 40V is probably phantom voltage. It is likely just open and capped or losse at the switch end.
 
 

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