Content of the material
- 3-Way Switch Wiring
- First, what is a three-way switch?
- Is it hard to wire a 3-way switch?
- What do I need to know before I begin?
- What about 4-way switches?
- Connect the fixture and switch
- Install the Fixture
- Understanding a Wiring Diagram
- How does the electricity flow through the switch?
- Wiring to Add New Lights from an Existing Fixture
- 4. Switching the Light and Fan from Separate Switches (Two Switches)
- About This Article
- Wiring a New Light and Switch Loop from an Outlet
- Replacing four-way light switches
- Questions about Wiring Switches
- The Grounding Screw Terminal
- Thats All, Folks!
3-Way Switch Wiring
Wiring a 3-way light switch is not a difficult task… there are only three connections to be made, after all. Making them at the proper place is a little more difficult, but still within the capabilities of most homeowners if someone shows them how. That's where understanding a wiring diagram can help.
First, what is a three-way switch?
When you want to be able to control a light from two different locations (for example, you want to be able to turn the stair lights on from both upstairs and downstairs), this is what electricians call a "three-way switch."
Is it hard to wire a 3-way switch?
To replace a switch is not difficult at all: Simply watch how you disconnect the old one and then put the wires back on the new light switch in the same position. Problems can arise when an extra switch is being added or if you forget which wire went where. That's when it becomes necessary to understand a little more about how a 3-way switch works and how to read a wiring diagram.
What do I need to know before I begin?
If you know what the purpose of each wire is, the task will become much simpler. This article will explain everything you'll need to know in order to wire a 3-way switch, with wiring diagrams and common wiring methods explained.
What about 4-way switches?
Read How to Wire a 4-Way Switch for instructions and wiring diagrams for wiring four-way switches.
Connect the fixture and switch
Photo 6 and Figure A show how to connect the light fixture. Start by mounting the fixture strap to the box. Strip the ends of the wires and connect them to the fixture.
At the switch, cut the cable about 12-in. beyond the box. Strip 8 in. of sheathing from the wires and push the cable through the knockout, leaving 1/4-in. or more sheathing visible inside the box. Trim the black and white wires to the same length as the wires they will connect to. Then strip the ends of the wires. Connect the white neutral wires with a wire connector. Connect the wires as shown in Figure A. Connect the hot wire to the side of the double switch that has the “jumper tab” between the terminals (Photo 7). Complete the project by mounting the light fixture, screwing the switch to the box, and installing the cover plate.
Install the Fixture
Trim the black and white wires to 8 in., leaving the ground wire long. Strip the ends of the wires. Connect white to white, black to black and bare copper to bare copper. Loop the bare copper wire clockwise around the grounding screw on the fixture strap before connecting it to the fixture ground wire.
Understanding a Wiring Diagram
Each diagram will show the two 3-way switches (but not the wall box they are contained in), the various cables and wires used in the configuration being discussed, and the light box and light fixture.
How does the electricity flow through the switch?
To understand the wiring diagram, you must know that the electrical current enters the system on the black wire in the power-in cable, passes through the switches, through the light fixture, and returns to the white wire in the power-in cable. If the circuit is broken anywhere (a switch turned the wrong way, a broken wire, or a bad light bulb), the current will not flow and the bulb will not light. For discussion purposes, each 3-way switch will be considered to have the common terminal connected to the right-hand traveler terminal when in the "up" position and connected to the left-hand terminal when in the "down" position. This is not necessarily true, however, it's simply helpful for discussion purposes.
Read the descriptions carefully and compare them to the diagrams to understand the diagrams. Each diagram will have a description of how the current travels in order to light the lamp.
Wiring to Add New Lights from an Existing Fixture
In this diagram, two new light fixtures are added to one that already exists. New 2-wire cable is run from the existing light fixture box to the first new box. From there, new 2-wire cable is run to the second new light box. If desired, more lights can be added after that by running new cable to each new light box.
At the existing light, the hot and neutral wires are removed from the fixture terminals and spliced to the new cable wires running to the first new light. A pigtail is also added to the splice to allow for reconnecting the existing light back into the circuit. At the first new light, the wires are spliced to the new cable running to the next light and to a pigtail to connect the first new light. If you want to add more lights after the second new one in this diagram, they can be spliced into the circuit in the same way.
4. Switching the Light and Fan from Separate Switches (Two Switches)
This is the most versatile way to electrically wire a ceiling fan with a light kit. It allows for separate control over both the fan and the light in the room. There are also lots of really convenient switches that put this dual control into one neat little package. Some even give you the ability to dim the lights – definitely a nice touch! There are endless choices when it comes to combination dimmers/switches you can use with your fan or fan/light.
Of course you can always simply wire up two single pole switches and you’re all set. And here is what the electrical wiring would look like for this situation:
It looks more complicated, but don’t sweat it. The basic idea is that your power supply line is feeding both switches. Each switch then feeds either the fan (black wire) or light kit (blue wire). All that’s left at this point is to tie together all the ground wires and neutral wires (respectively). Keep in mind again that we assumed 12/2 with ground for the lines going to and from the switches, so be sure to clearly label them as “hot” wires by wrapping black electrical tape around the white ends.
While code makes certain stipulations, there are typically different ways to accomplish a wiring connection. Case in point, the above method was shown using standard 12/2 wire. If you opted for 12/3 wire, you could accomplish the same dual switch connections with a little bit less work:
What you are doing here is using the single hot (black) wire to power both the switches. You can do this by jumping a longer length of wire to both switches. Jumping means that you strip the insulation away from a small area of wire. Make it just large enough to loop around the hot terminal. You then loop that exposed wire around the hot terminal of the first switch. Finally, strip the end and connect that to the second switch. The hot returns are then the red wire and the white wire which you tape black (on both ends) to designate it as a hot wire.
You can also jump the ground wire. This method of jumping wires is nice in that it eliminates the need for wire nuts. It also makes for a simpler wiring scheme (and gives you more room to work in the box!)
Here’s a similar way to do it using 12/3 wire with wire nuts in lieu of a jumper wire:
About This Article
Co-authored by: Daniel Stoescu Master Electrician This article was co-authored by Daniel Stoescu. Daniel Stoescu is a Master Electrician and the Owner and Operator of Home Tech Solutions, LLC in Hampton, Virginia. With over a decade of experience, Daniel specializes in wiring residential, commercial, and light industrial structures. The Home Tech Solutions team has over four decades of combined experience and offers comprehensive solutions for residential electrical needs. This article has been viewed 166,121 times. 3 votes – 100% Co-authors: 7 Updated: August 17, 2021 Views: 166,121 Categories: Lighting
Wiring a New Light and Switch Loop from an Outlet
This drawing shows the wiring for adding a new light and switch with the fixture coming first in the circuit. New cable is run from the receptacle to the new fixture location and a switch loop cable is run from there to the new switch location. The switch loop is a 3-wire cable to comply with NEC requirements of a neutral in all new switch boxes.
At the receptacle, the always-hot wire is spliced to the black wire on the light fixture cable, and to a pigtail that connects back to the hot terminal on the wall outlet. At the light fixture box, the black wire is spliced with the black wire running to the switch. At the switch, the black wire is connected to the new switch.
Back at the source, the neutral wire is spliced to the white wire running to the light and to a pigtail connecting back to the receptacle neutral terminal. At the fixture, the white connects to the neutral terminal on the light. The red wire from the switch loop is connected to the hot terminal on the light and at the other end to the new switch. The white wire is capped with a wire nut in the new switch box.
Replacing four-way light switches
Turn off the power to the switch at the circuit panel or fuse box.
Unscrew and remove the switch plate; then use a voltage tester to make sure that the circuit is dead.
Unscrew the switch from the electrical box and pull it out with the wires still attached.
This switch has at least four screw terminals. It may also have a fifth, ground terminal (green).
Mark the location of the four wires with tape so that you can replace them on the new switch; then remove the wires from the switch.
Alternatively, you may choose to transfer one wire at a time from the old switch to the new switch.
Attach the wires to the corresponding terminals of the new switch.
If the existing switch has a green ground wire, attach it to the green terminal on the new switch or to the electrical box.
Push the new, wired switch back into the electrical box and screw it in place.
Screw on the switch plate and turn on the power.
Questions about Wiring Switches
Question from John in Lexington, Kentucky: How is the Wiring for a New Light Switch and Fixture added to an Existing Switch?
I have an existing light switch, and I want to add a second switch for a new light that will be operated separately. The power comes into the switch which operates a single light at the end of the circuit. I know I have to change the gang box and I’m fine with running cable and installing plates but I’m not clear on the best way to add the wiring. Is there a simple way to do this or should I get an electrician?
Dave’s Answer: Adding a Light Switch and Fixture to an Existing Switch
The task of installing additional wiring for a light switch and new light fixture will depend on available access to the proposed location. Hiring a qualified electrician will ensure that the installation is performed correctly where the existing circuit wires will be identified, and new circuit wiring will be extended to the new light switch and then out to the new light fixture. The method used to install the new wiring will depend on the wall structure and location in the home. Special attention will be given to the existing circuit capacity, the wire type and size, as well as making sure the additional wiring is protected and installed according to all the electrical codes that will apply.
Question from Denny, a Handyman in Sudbury Ontario Canada, Canada: How do I close off an existing light and add two new lights off of the existing light switch?
I have a single light on a single switch in my kitchen ceiling. I want to close off the existing light and run two new lights off of the existing light box. It is not far from the existing light, so will I need to run wire from existing box to the two new boxes. How do I wire it considering I don’t want a light fixture in the current spot. How do I close it off?
Dave’s Answer: Adding New Light Fixtures off an Existing Light Switch
The easiest way to add new light fixtures is to run the new wiring to the existing light fixture, splice the wires together as the old fixture was connected and then place a decorative blank cover over the fixture box. Arlington makes a white blank fixture box cover that works very well for this type of application. If you would like to remove the light fixture box, and there is access to the attic area then the fixture box could be removed, and the wiring installed into a new junction box located in an accessible location where the new wiring for the additional light fixtures may be connected. The new junction box must be securely mounted and an blank cover must be installed after all the wiring connections have been completed.
Question from Rob, a Homeowner in Ottawa Canada: I have what I am sure is a simple question, but I want to be sure as the new light switches I want to install are expensive digital switches.
The new switches are obviously meant to be 3-way as they have a Red wire in addition to Black, White, Green. The old switches are not 3-way though and the electrical box they are in does not even have RED wires. The one old switch is the only switch controlling one light, while the other old switch is the only switch controlling three other lights.
So when I put the new switches with the Red wires in the box, what do I do with the Red wires?
My guess would be that I just cap off the Red wires from the new switches as they are not needed, but I do want to be sure.
Dave’s Answer: Spare Switch Wire
You are correct, when s new switch will not be used as a 3-way switch the Red wire is capped off with a small wire connector or electrical tape.
Question: Can one single pole switch control another single pole switch?
Dennis from Denver, Colorado asks: Under the International Electrical Code, is it permissible for one single pole switch to control another single pole switch? The original intent was to have three-way switching which didn’t happen.
Answer: Two single pole switches controlling each other and a light fixture would not function correctly therefore technically it would not be compliant with electrical codes. In a situation such as this you should consider the option of installing a matched pair of Master and Slave switches which will act just like two three way switches. This type of switch may be found at most hardware stores or electrical supply distributor.
The Grounding Screw Terminal
For safety, always install a three-way switch that has a grounding screw. It is connected directly to the metal strap of the switch, and it may be located on the bottom of the switch, as shown here, or it may be on the side or another location. If you run across an older switch without a grounding screw, it should be replaced with a newer, grounded switch.
Thats All, Folks!
Hopefully, this guide will get you on your way to installing a ceiling fan and making all of the required electrical connections to get it up and running smoothly. A ceiling fan makes a great addition to almost any room. It’s one of the easiest projects to complete and really makes an impact in your home. It can also make you look and feel like a real handyman.
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