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How can a light fixture be controlled by two 3-way switches using only 2-wire cables with ground?

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2015-07-15 21:22:44
2015-07-15 21:22:44

CAN'T. Must have 3-wire w/ground.

[First off, I want to admit that the wording of this answer is skewed. However, if you read the answer you will understand why. It is techinically correct in terms of the NEC. -TJNII]

The idiot that wired my house did this. To add insult to injury he connected the hot to one circuit and the neutral to another. I was almost electrocuted because of it.

Do it right or don't do it at all. Your negligence may kill someone.

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you can ground it to the fixture electrical box.

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Connect the ground wire from the light fixture to the ground wire in the ceiling box.

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This requires 3-way switches that have three separate terminals (plus ground). The method of wiring depends on where the light fixture is in relation to the switches and the feed wires. Most brands of switches contain wiring diagrams to help the installation.

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The fixture box should have a ground screw on the bottom of the box. Sometimes you have to move other wires out of the way to see it. Just reconnect the fixture ground wire to this screw.

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If you're asking whether you have to connect the fixture ground to the house ground, you do. The idea is to connect any exposed portion of a metal fixture to ground, keeping anything you would be able to touch from having a hazardous potential on it. The way to do this is to connect the fixture ground (which is connected to the metal chassis) to the building ground (which comes from your electrical panel).

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Is this a fluorescent fixture? Most fluorescents will not start if the fixture is not grounded. Make sure the fixture has the branch circuit ground wire properly connected.

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There is a way to wire a light fixture controlled with two 3-way switches using only 14-2 cable. Run a length of 14-2 cable from each 3-way switch to the light fixture and a third one between the switches to act as travelers. This is not an optimum method for wiring this arrangement, but it is possible in a pinch, if no 14-3 cable is available. This method leaves an unused conductor in each of the cables linking the light fixture to a switch, each of which must be tied to ground at both ends to indicate they are not carrying current. The conductors that are used must conform to the color convention for hot and neutral conductors, and any white conductors that are hot must be wrapped in red or black tape.It's important to remember that the travelers and switches must always be situated between the hot electrode of the power source and the load (light fixture), to prevent any of the wires in the light fixture from being live when the switches are off (no current flowing in the circuit). Also, if metal boxes are used, the two cables must run through the same hole in any box they enter to avoid problems with eddy currents.A variation of 3-way switch wiring employing 14-2 cable is one in which two widely separated light fixtures are controlled, such as at the top and bottom of a staircase. In this variation, the light fixtures must be connected in parallel, necessitating that an additional conductor be run between the fixtures. As a result, some parts of the circuit will contain four conductors, which can be provided using two lengths of 14-2 cable, while other parts will need only three conductors, depending on the relative locations of the light fixtures and switches

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All newer installations have a ground wire (bare) in with the other conductors. eg. 2c #14 with bare ground, 3c # 14 with bare ground. These bare wires are used to ground the boxes that they travel through. In a proper installation, one of the wires should be under the ground screw which is located on the flat bottom of the box. From under the ground screw this wire should be wire nutted together with all the other ground wires in the box. If the fixture is a fluorescent fixture, usually you have to provide a ground wire from the fixture to the group of ground wires in the box.

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If you don't have the wire then you just can't ground it. This should not be too much of a problem. Most light fixtures are not grounded and some don't even have ground wires.

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If you are talking about the lamp then the answer is no. If you are talking about the fluorescent fixture, it should be. It is the fixture grounding that helps the tube to ignite. because of the close proximity to the metal of the fixture. There are many occasions when the fixture will not operate, but as soon as the ground is connected the fixture operates fine.

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If there is a red wire in the fixture box it sounds like the fixture is three way switched. The travelers are coming from one of the two switches and the cable is going to the second switch.See related links below.

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The green wire on the light fixture is a ground wire. If there is no ground wire in the conduit, the green wire should be attached to the metal box with a screw.

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The fixture will not be grounded. As long as the hot and neutral are connected the light will work.

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If you mean 2 bare copper wires those are the ground wires. Tie them together and then connect the light fixture ground wire which will be green or bare copper to those ground wires.

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All the switches to be tried first. 2 out of 3 must be switches of the ground floor room. So which ever doesn't work for the ground floor electronics must be first floor bulb switch J

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You need two 3-way switches. To see a diagram use your favorite search engine and search for 3-way switch wiring. Each switch has a common connection point and two other terminals. Basically connect the "other" terminal on 1 switch to either "other" terminal on the second switch and then do it again for the remaining "other" terminal. Then connect the common on one switch to the fixture and the common on the remaining switch to supply voltage. Tie neutral and ground for fixture and supply to the white and bare wires respectively.

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Connect the white and black wires back on to where the other black and white wires connected. There should also be a green pigtail coming out of the fixture which will be the ground. If it has a chain, then the wire running through the chain will be the ground wire.

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You can attach/splice into the power feed to outlet (ways of doing this can vary with how the outlet is wired but make sure that all or part of the outlet isn't controlled by an existing switch). You can then take the hot, neutral and ground to a light fixture or to the first switch, then to the second switch. It is normally easier to do this project by taking power to the light (s) first, with 2 wire drops to the switches, from basement or attic.

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Wiring a 2 wire fixture to 4 wire outlet depends on configuration of wires in outlet box. If you have 2 white and 2 black I will assume there are more lights controlled by the same switch. 1st scenario attach both black wires to black of 120 volt fixture. Attach both white wires to white wire from fixture. atach ground to box or ground wire. 2nd scenario attach white neutral to white from fixture, Attach black hot to white going to switch. Attach black from switch to black from light Fixture. If you need further help I recommend hiring a contractor. Take a look into contraxtor.com

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Yes. Connect Black to Black, White to White and bare ground wires together.

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Don't worry about it some fixtures have no ground terminals. just shove the groung wire to the back of the box. Correction, if the fixture is metal and it shorts out, the metal surrounding the fixture could become electrified. That's why fixtures today are normally grounded to their mounting plates and then the lead is attached to the incoming romex. In the past, attaching these plates to metal boxes (either grounded by an incoming wire or grounded to the BX cable) eliminated the need for a ground wire. If the hot wire hit or shorted to the fixture, it would blow a fuse or circuit breaker. Many electrocutions and fires later, the folks at Underwriters realized that even that method of grounding wasn't sufficent (the old aluminum boxes and bx cables were crappy conductors. Solution; (and I practice what I preach because I remodel many old homes) get a little creative and spend the extra time to wrap a little ground wire to a mounting screw, or piece of metal, on the mounting plate of the fixture and then attach it to your incoming romex ground. On an old fixture, it could mean the difference between a fire and a tripped circuit breaker. If you have any metal boxes, old or new, ground to those too. <><><> Connect a pigtail to the metal canopy, and use a wire nut to connect the safety ground to it.

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Very often the ground wire in the fixture is ignored, or just connected to the box, if there isn't a conductor to connect to. This, however, is a code violation as any fixture with a ground wire is required to have it properly connected to an equipment grounding conductor back to the panel. This is for YOUR SAFETY. Technically you should rewire the circuit with the proper conductors. It is BAD PRACTICE to connect the ground wire to the neutral or white wire because this could create a hazard of its own.

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Connect black to black and white to white from the switch. Your old fixture may have had wiring for multiple bulbs so they could be switched separately.


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