RED electrical wire in ceiling junction box

Thanks in advance.
I am installing a light fixture with three wires: Black - Hot White - Neutral Copper - Ground
The Junction has four wires coming out. They are all capped as this junction box has never been used. They are: Black White Green which is ground ?RIGHT?? RED ?????
Do I forget the RED wire and leave it capped??
Some of the other posts mention RED wire used with a FAN???
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Green or bare is ground, white is neutral. If you have one wall switch, you need to see which of the red or black wires are hot, when the switch is on, and dead when it's off, and use that wire for the "hot" of the fixture

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Maybe one leg of an old three-way switch?
About twenty years ago, when I bought my present house, I converted two three-way swtches to one single-pole switch. I capped the unused switch box and covered it with drywall.
I can't for the life of me tell you exactly what I did, but it's been twenty years and the place hasn't burned down.
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wrote:

It takes 22 years for buried switches to spontaneously combust
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It is possible that you have a pre-wire for a ceiling fan. Black for fan, red for light. White neutral, green/bare ground. See if you have 2 switches at the wall. Otherwise, see if Red-white or black-white is switched. Cap the remaining red or black, as the case might be.
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On Mon, 24 Nov 2008 17:16:05 -0800 (PST), professorpaul

What he said.....You should be able to take a tester and check. The black should be hot regardless of the switch position, and the red should work from the switch.
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So I think that I understand that:
Black is HOT
RED is HOT
One is HOT ALL of the time
One is HOT only when the switch is ON
Correct???
Thanks again
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That is probably the case. There are three other possibilities worth considering.
1) Red and black are both always hot. Not likely, but possible. 2) Both are on separate switches. We have this arrangement in a room with two fans, to we can turn both fans on/off with one switch and turn both lights on/off with another switch. 3) It was wired by someone who didn't know what they were doing, in which case, anything is possible.
If you have tester (and know how to use it without killing yourself), test it to be sure.
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Oh, and if you don't have a tester, get one. The cheapest one you can find would be sufficient for this test. Be careful.
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DMM (Digital multi meters) even cheap ones can be very misleading especially to someone not electrical!
Witness the number of post here that say something along the lines of "I thought lighting circuits were supposed to 115 volts. But I am measuring 35 volts on a wire that I thought was disconnected. What's happening?".
Or occasionally testers being blown up because they were switched to the wrong range; for example if set to read 5 volts many of them don't like 115! More elaborate ones may resist damage by automatically switching themselves to correct range and displaying it but with more features are trickier to use.
One of the best testers is a spare 115 volt bulb, almost any type will do. A 15/25 watt appliance bulb is smaller, easier to carry and being low wattage won't get too hot to handle. But any low wattage bulb will do. To test if something is live, with or without switches on or off, two wires from the lamps socket can be touched, one to the white neutral (zero volts) and the other to the wire to be tested, to see if there is electrcity present.
As other posters have mentioned the black is usually the live wire from the supply breaker. A red wire may be what is sometimes called a 'switched live' ; in other words it is live only when a certain switch (often a lighting wall switch) is ON.
Many wall switches in this house are wired black/red (not black/ white). The electrcity travels down from the ceiling fixture box to the wall switch on the black wire. When the wall switch is ON the electric current travels back up the red wire to the ceiling box and there is connected to the live wire of the light (or whatever) so that it is energised and comes on. Note:
Note: If the black wire was connected straight through to a light fixture (or whatever), thereby by-passing the switch our ceiling light/ s would be lit all the time!
Any help? Be careful and make good tight connections including the ground/earth.
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Thanks.
I finished changing the 5 light fixtures. 3 had a RED wire. I found out that the RED wires were for FAN power and they had separete switches on the walls.
Today, I am puting dimmers on some of the fixtures. SO EASY!
Next project, 32 foot long - 11 foot high medal stud wall ;)
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On Mon, 24 Nov 2008 16:42:55 -0800 (PST), " snipped-for-privacy@yahoo.com"

Be very careful with the RED wire. That wire is connected to Washington DC and is used to detonate nuclear weapons. One wrong connection and the whole world is history.
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The red wire is a spare "hot" line so that you could install two separately-controlled circuits in the fixture if you wish. For example, in a dining room the fixture over the table could have a circuit for general room lighting and another for downlighting/accent lighting on the table. An outlet box where a ceiling fan might be installed could use a circuit for the fan motor and the second one for a fan light kit. That gets rid of the pull cords you see on fans.
The red wire is sometimes used for 3-way and 4-way switch arrangements too.
I wish including the red wire in junction boxes was standard practice. It's so easy to do when running the wiring and so hard to do later.
TKM
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On Sat, 29 Nov 2008 16:16:55 -0600, snipped-for-privacy@home.com wrote:

[snip]
That was supposed to have been disconnected in 1991, but probably wasn't completely (there are too many redundant connections in Washington DC, and we paid for all those).
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A red wire in hot, just like black. The electric code makes no distinction between red and black; it's up to the installer how they are used. Maybe the red wire is switched and the black is hot all the time, or vice versa, or maybe the are each on different switches (one for the fan and one for the light.)
The white wire is almost always neutral (and if it's not, there should be black or red or blue etc. tape on the end to tell you that it's /not really/ white.
The green wire is always ground.
Put a test lamp between the white and (one at a time) the red and black wires, then play with the switches to see what you've got.
HTH, Bob
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