First of all, does this mean that the light is permanently on?
Basically what a switch does is interrupt the current flow going to the light. When you turn it on, it makes the connection that is already there with plain wire.
So, installing a switch involves finding the hot wire that goes to the light, cutting it, and connecting each end of the switch to each section of wire. YOU MUST DISCONNECT POWER BEFORE DOING THIS, OR YOU WILL ELECTROCUTE YOURSELF.
Also, completing a project like this in a manner that is up to code is quite a bit more complicated than my explanation. The code is there for your safety, following it is common sense. You must use an approved switch, in an approved box, mounted securely in an appropriate manner, etc. If you aren't completely sure you know what you're doing, don't do it.
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
Your question implies that you want to wire a new branch circuit controlled by a switch using the existing light fixture. DON'T DO IT! It is a code violation. The existing light has a switch already. you cannot control another light with another switch when the first light is OFF. There are safety reasons for not doing this. If you wire the new light from the hot side of the existing light, you can be shocked even if the new switch is OFF.
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.
If you want to control the new light off of the existing switch then connect a black wire from the new light's black wire to the existing light's black wire and the new's white to the existing lights white wire and grounds to grounds. Or if there is no existing light; connect the black wire from the new light to one terminal screw on the SINGLE POLE switch (but not the green grounding terminal) The other terminal on the switch is connected to a black, hot all the time, wire which is paired with a white neutral wire that will connect directly to the white wire on the light. Grounds to grounds. Use 14/2 with ground wire on 15 amp circuit breakers and 12/2wg wire on 20 breakers. For more about SINGLE POLE switch wiring see the attached link.
You have to pull a new wire. There is no way to do it with the existing wire, at least no way you should do it and be in code.
You need to take a new wire into the outlet and to your new switch box. Black (hot) to black and white (neutral) to white Also splice the ground wire through. In the switch box you'll have your new wire from the outlet and a wire going out to the new light. Incoming black wire to one terminal on the switch and the black wire going to the light on the other terminal. The neutral wires get spliced together.
The black and white wires that go to the switched light should be wired in parallel to your new light if possible. There should be wirenuts on the existing light making the connection to the light. There may also be a bare ground wire. Using the same size wire, likely 14 AWG, connect the new light wire to black, white and ground of existing light.
If you are adding the pull chain to an existing fixture then the pull chain switch should have two wires. Wire nut either one to the hot wire coming in and the other to the black wire of the fixture.
with a standard 1 pole light switch (one switch operating the light) it is black wire to black wire and white to white (non grounded)
Run a wire from the light to the switch. At the light connect the black power wire to the black wire to the switch. Not wrap some black electric tape at each end of the white wire going to the switch (This indicates that the wire is potentially hot and not a common wire). At the switch connect the black wire to one side of the switch and the taped wire to the other side of the switch. Connect the ground (bare) wire to the green screw on the switch. Now at the light connect the taped white wire to the black wire feeding the light and connect all grounds together with a wirenut.
You can if you have a neutral wire present. If the existing switch is what is called a "switch loop" then you can not change the existing switch to a switched outlet. You can identify a switch loop by looking at the wires coming into the switch bow. If there are only one set of wires usually a black and white and they go directly to the switch then you have a switch loop
Current flows through a wire when a light switch is turned on.
Send power from the switch to the first can light. Then send a wire from that can light to the next can light and then to the last can light.
You can't. You will need a 3way switch at each end with 12/3 or 14/3 wire run between them. Power at one switch and light wire at the other switch.
Using 14/2 or 12/2 wire, black, white and bare. Bring the hot/black wire in the light down to the switch on the black wire, through the switch and back to the light on the white wire. Connect the white wire in the power wire to the white wire in the light. Connect the white power wire from the switch to the black wire in the light. Run the black and white wires in the first light to the second light. You should wrap the white power wire from the switch with black electrical tape to cover the white so that the next person realizes it is a power wire.
Two options. Change the fixture to a keyed pull-chain, or add a pull-chain adapter to the existing fixture. Both available from Home Depot and others for about $3.
You have a 3 way switch. Your black wire is the hot wire. Your green wire is the ground wire. Your red and white wires go to the light and other switch. You should have gotten a wiring diagram with your switch.
Sounds like you are are installing a single pole switch (your load is controlled from one location only). If your existing switch is hooked up to a black and a white wire you are dealing with a switch loop and that white wire is being used as a hot wire. Make sure the circuit breaker is off of course, and hook up the black wires on your dimmer to the existing black and white wires on the original switch (polarity doesnt matter here) the green wire on the dimmer is a ground and should be hooked to a bare copper wire or green wire in the box if it is there.
All a switch does is separate the hot side of a voltage source from the light. This means you put the switch "in series" with the black wire going to the light fixture. The black wire from supply goes into one terminal of the switch and the black wire going to the light goes on the other terminal. The switch is grounded with the bare wire from supply and the white wires coming from supply and going to light are connected with a wirenut. The bare wire grounds are also connected with a wirenut.
you probably can't, you need a neutral and a live wire to make a fan work. switches normally only have live wires.
You always switch the HOT side of the light, never the neutral. This would be the black wire from your voltage source.
Install the switch in the wall outlet box you have installed. Now run a 12/2 or 14/2 wire from the switch to the light fixture in the ceiling. Run the exact same size wire that is already powering the light. Connect the ground wire coming from the light switch to the ground wires in the ceiling box. At the light in the ceiling cut the black wire powering the light. Cut only that wire. Now strip the 2 black wires back and connect the white wire coming from the wall switch to one of the black wires and the black wire coming from the wall switch to the other black wire. At the wall switch connect the ground wire to the ground screw on the single pole switch. Now connect the white and black wire to either screw. Does not matter which one. Now when you turn the switch off you are breaking the flow of electricity to the light. This is called a switch leg.
If you have one wire into your switch box for your light. this is called a switch leg, the dimmer should be wired across the black and white wire wires.
Bring the hot power wire into the wall switch box and run another wire out to the outlet. Tie all the whites together in the switch box under a wire nut and shove this back into the box. Tie the black incoming wire and the black wire going to the outlet together and jump a wire off this to one of the screws on the light switch. Connect the black wire going to the light to the other screw on the light switch. Connect the white/black wire to the outlet.
by a parellal current switch.