How to Wire a Light Fixture to an End-of-Run Switch. One thing you will discover when you begin doing your own electrical work is that there are a number of wiring configurations that can be incorporated into any task. Basically, you have no idea what routes the electrician who wired your home followed. And if the previous homeowner tried his hand at his own electrical work without any electrical guidance, then you could really be surprised when you open up the switch boxes! One such job that could give a homeowner pause is wiring a light fixture to an end-of-run switch. Do not worry, here is how to do it!
Things You'll Need
Pliers or multipurpose tool
Wire connectors (wire nuts)
When you hear the term "end-of-run" it means that is where the circuit ends. So, an end-of-run switch is the last component in the wiring of a circuit, and in effect, the wire feeding the switch is coming from the light fixture and not the other way around.
This tutorial will explain the job as if there is currently no light fixture or switch installed in the room; just a ceiling electrical box with a circuit in it. This will give you a better idea of how the circuit is run in the first place. So, the first thing you will have to do is turn the circuit's power OFF. Toggle the breakers in your electrical panel and use your voltage tester to ensure that the correct circuit is off.
You will have to run the electrical circuit to where you are going to have the light switch. Refer to my other article: "How to Fish Wire Through a Ceiling" to help you with that task (see Resources below).
Now, you should have your wall box installed with your newly run wires hanging out and your ceiling box should have the original three-wire circuit as well as the new wires that you ran for the switch. Use your wire strippers to strip about 3/4 inches of insulation from each wire.
Twist the two ground wires together using your pliers or multipurpose tool. Take a piece of electrical tape and wrap it around the insulated section of the white wire that is heading to the switch.
Grab your light fixture and twist the fixture's ground wire in with the other ground wires and secure them with a wire connector or wire nut. Take the white wire that is coming from the circuit (the original line) and the white wire from the fixture, twist them together and tighten a wire nut over them. Then, take a strip of electrical tape and wrap it tightly around the wire nut where the end of the connector meets the wire.
Take the black wire from the original circuit and tie that wire together with the white wire to the switch (the one with the black electrical tape wrapped around it). Secure a wire nut over them and wrap them with electrical tape like you did with the other wires.
In the ceiling box you should have two wires that are not yet connected: the black wire from the fixture and the black wire from the switch. Connect those two wires together, tighten a wire nut over them and tape them. Now, finish installing the light fixture to the ceiling box.
At the wall switch you are going to strip 3/4 inches of insulation from each wire and once again wrap a strip of electrical tape around the insulation of the white wire. This is performed so whoever performs work on this circuit in the future will know that the white wire is carrying voltage and it is NOT being used as a neutral.
On the switch, connect the ground wire to the ground screw, the taped white wire to the bottom side screw and the black wire to the top side screw. Wrap electrical tape around the switch so the terminals are covered.
Now, just secure the switch to the wall box, screw the switch plate on to it and turn the circuit back on. Flip the switch and your light should turn on! That is all it takes to wire an end-of-run switch!
Whenever you are using the white wire as a feeder or a switch leg it is important to mark it as such by wrapping electrical tape around the insulated section. This not only reminds YOU that the wire is HOT, but it also warns anyone who may be working on the circuit in the future.