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When using the correct size wire, there are several possible configurations of power connection, lighting outlet, and the two 3-way switches. Power can come from the panel to one switch or the other, or to the light, whichever is convenient. The light can be physically positioned between the switches or at the end of the two-switch series.
Each configuration requires different handling of the hot, switched travelers, and neutral wires. In every case, there are runs that require three parallel conductors, whether for neutral, hot or travelers, not including any grounding wires. A 3-wire cable is highly recommended for this application.
If there are more than two switch locations, a 4-way switch goes between the 3-way switches to crossover the two travelers. Two 3-conductor cables are used for this portion, including a bypass connection for the un-switched hot. Asking this question shows you are probably not quite ready to take on this particular task.
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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
with 2 3-way switches you need 12/2 to the light and 12/3 in between the 2 switches. you can also use 14 gauge wire
If your wiring it up for a light switch, then you will need 2 3 way switches, this will allow you to turn on and off lights from 2 locations
You must use what is termed a 3-way switch. You can get a circuit diagram by searching the internet for 3 way switch diagram.
To help you out, it is called a three way light switch. See Related Links below.
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.
If the question is, can I wire a switch to an existing light fixture (and I must assume that it's something like a pull-chain light fixture), the answer is yes.If the question is, "how do I wire a switch to an existing light fixture that has no external switch", the answer is, "in series".The attached web site gives simple instructions on how to wire a basic light switch to an existing light.See sources and related links below
The light is wired the same as any voltage fixture. Bring the source voltage to the fixture and connect it to the two fixture wires. If you want to control the off-on of the fixture take the source voltage to a switch first and then out of the switch to the light fixture.
To the black wire on the fixture.
Piggyback off the box for the existing light. Run a wire from the existing junction box to a new junction box (which is placed wherever you want the new fixture). Then, in the existing box, connect the wire coming from the switch, the wire for the existing fixture, and the wire for the new fixture together using wire nuts. Wire up the new fixture, and presto, you have two fixtures on a switch where there was only one before.
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.
If the question is, can I wire a switch to an existing light fixture (and I must assume that it's something like a pull-chain light fixture), the answer is yes.If the question is, "how do I wire a switch to an existing light fixture that has no external switch", the answer is, "in series".The attached web site gives simple instructions on how to wire a basic light switch to an existing light.See sources and related links below
The light is wired the same as any voltage fixture. Bring the source voltage to the fixture and connect it to the two fixture wires. If you want to control the off-on of the fixture take the source voltage to a switch first and then out of the switch to the light fixture.
To the black wire on the fixture.
Piggyback off the box for the existing light. Run a wire from the existing junction box to a new junction box (which is placed wherever you want the new fixture). Then, in the existing box, connect the wire coming from the switch, the wire for the existing fixture, and the wire for the new fixture together using wire nuts. Wire up the new fixture, and presto, you have two fixtures on a switch where there was only one before.
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.
Connect the ground wire to the metal box.
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.
By earth wire I am assuming you mean the bare wire and that a black and white wire are connected to the light. If when you connect the earth wire and breaker trips then there is a short between black and earth. It could be a bad ground connection, an internal short in the light fixture where black wire "hot" is connected to metal on the fixture through a nick in wire.
Connect the black wire to the incoming hot wire and the red wire to the out going load.
Just install the new fixture with black to black, white to white, and cap off the ground wire on the new fixture. It'll be fine.
Yes, that is the correct connection.