How to Connect Three-Way Switches to Lights in a Series
Three way switches control lights from two different locations. This type of switch is used when a light or series of lights needs to be turned on or off from different locations, such as the top and bottom of stairs or in a long hallway. Wiring them can seem difficult, but once you understand how the series works it isn't as tough as it seems. Does this Spark an idea?
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Things You'll Need
- Three way switch
- Three way wire
- Razor knife
- Electrical pliers or wire strippers
- Screwdriver
- Wire nuts
- Electrical tape
Instructions
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1
Disconnect the power to the circuit box. You can shut off the single circuit you are working on, or to be safe the entire box if desired. Check to be sure you have turned off the correct circuit before performing any work.
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2
Open the switch box that will house the first three way switch, and that the power source is wired into. Remove the standard switch.
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3
Prepare your three-way wire that will run to your light fixtures from the three-way switch boxes. Strip one end by slicing into the insulation gently with a razor knife. Use the electricians pliers or wire cutters to strip the insulation off of 3/8 of an inch from the end of each wire for connections to the three-way switch.
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4
Connect a small piece of green ground wire to the ground connection screw in the three-way switch box. Using a wire nut, twist that wire together with a section of ground wire that you connect to the three -way switch, the green ground wire from the two-wire power source wire, and your new three-wire cable. Use a wire nut and connect the white negative wire from the three-wire cable to the white wire in the two-wire cable from the power source. The white negative wire does not connect to the switch.
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5
Connect the black wire from your two-wire power source wire to the brass screw on the three way switch. Connect the black and red wires from your three-way wire to the other two remaining screws on the switch. The first three-way switch in the series is wired.
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6
Run the three-wire cable you have connected to the three-way switch from the three-way switch box to the first light fixture in the series. Cut two sections of two-wire cable that will run between light fixtures.
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7
Connect the white negative wires from the three-wire cable, both sections of two-wire cable that will run between the light fixtures, and the light fixture itself. Twist these together with a wire nut.
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8
Twist together the black wires from the three-wire cable, to one section of the two-wire cable. Connect the other section of black wire from the two-wire cable to the light fixture. Twist together the white neutral wire from the two-wire cable that will run to the next fixture with the red wire from your three-wire cable using a wire nut. Wrap a piece of black electrical tape around the end of this neutral wire to indicate it is a hot wire.
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9
Cut the final section of three-wire cable that will run from the last fixture to the end three-way switch. Prepare the ends by stripping them as before, cutting away the insulation 3/8 of an inch from the end.
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10
Connect the next light fixture in the same manner, using the two sections of two wire cable that came from the first fixture, the current fixture, and the three-wire cable that will run to the three way switch. Connect all the green ground wires together and twist in a wire nut. Bring the neutral wire from the two-wire cable that you connect to the red on the opposite end, wrap it with tape to indicate it is hot, and twist into a wire nut with the red wire from the three-wire cable that runs to the final switch. Take the black wire from that same two-wire section and twist it together in a wire nut with the white neutral wire from the three-wire cable running to the switch, marking that white neutral with black tape to show it as a hot wire. Now take the white neutral from the other two-wire cable section and attach it to the light fixture. Run the black wire from that same two-wire section to a wire nut connected with a section of black wire from the light fixture, and the black wire from the three-wire cable that runs to the last switch.
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11
Run the three-wire cable to the final three-way switch box. Take the white neutral wire that is now hot and wrap the end with black tape to indicate the change, and connect it to one of the black connectors on the three-way switch. Connect the other black wire and the red wire to the switch. Now connect the green ground to the green ground screw in the switch box, run another piece of green ground wire to a wire nut, twist it together with a final piece you connect to the three-way switch.
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12
Screw the three-way switches into the box mounting brackets, and restore the power to test your light series.
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Tips & Warnings
Working with electricity is always a job in which to take extra care in both protecting yourself and making sure you have made the right connections. An improperly wired job can result in injury or fire and potential property loss.
References
- Photo Credit light switch image by Jim Mills from Fotolia.com
