The third terminal, known as the common and is a darker color, serves one of two purposes depending on where it is positioned in the circuit run: Either it accepts the incoming hot wire from the power source, or it connects to the hot wire that leads onward to the light fixture. Many aspects of the 3-way switch can differ drastically from the standard wall switch. It is therefore not uncommon for homeowners to have issues when dealing with 3-way switches. In this article, we are going to show you how to wire 3-ways switches, as well as troubleshoot and resolve problems to do with these kinds of switches.
How to Troubleshoot a 3-Way Switch
While you do not need to troubleshoot a 3-way switch all the time, it may be necessary when the switches are not working. Check this too: Ecobee Switch+ How to & Troubleshooting Guide Assuming your bulb is in good condition and it is the switches that are not turning the lights on or off, or you have noticed that one of switches is bad, you have to troubleshoot. Another situation where you may need to troubleshoot is when the wires are not connected properly. To troubleshoot a 3-way switch, follow these steps: When replacing a defective 3-way switch, it is highly recommended you replace the two switches at the same time. This is because it is assumed since both of them were installed at the same time, then the other is likely to fail any time soon as well. Here is how to replace a defective 3-way switch:
How Does a 3-Way Switch Work?
3-way switches are typically used to control a light fixture from two different locations. For example, a stairway or hallway might use a pair of 3-way switches at each end so that lights can be turned on when approaching one end of the stairway or hall, then turned off from the other end. How these switches work is that when both toggles are up or both are down, the circuit is complete and the light fixture will be illuminated. Otherwise, when the toggles are in opposite positions, the circuit is interrupted and the light fixture turns off. This allows either switch to control the on/off function of the light fixture at any time.
How is a 3-Way Switch Wired?
3-way switches can be wired in a number of different ways, depending on where they are located relative to the light fixture in the circuit cable runs. For instance, they can be arranged so that the feed cable runs to the first 3-way switch, then to the light fixture box, then to the second 3-way switch. They can also be wired so that the cables run through both 3-way switches, then to the light fixture. This is a more common configuration, in which the wiring connections are done as follows:
At the location of the first 3-way switch, the feeder wire from the power source is a 2-ire cable with ground. This means there is a black hot wire, a white neutral wire, and a bare copper grounding wire. At this first switch, the black feed ire is connected to the common terminal screw on the switch. The grounding wire is connected both to the switch using a pigtail wire, and to the second cable run passing onward to the next switch. If the switchbox is metal, it also must be pigtailed to the grounding wires.The cable run connecting the two 3-way switches is made with three-wire cable. The black and red wires are “travelers” and are connected to the traveler screw terminals on the two switches, which is what allows the switches to turn the lights on and off in a flexible manner.Since switches don’t have white-colored neutral wire connections, the neutral wires at the boxes are simply joined together so they pass through, onward to the light fixture box.At the location of the second 3-way switch box, the wiring is the same as at the first switch, with the traveler terminals connected to the traveler wires coming from the first switch. However, at this second 3-way switch, the common screw terminal is connected to a black hot wire that leads onward to the light fixture. The white neutral wires, once again, are simply joined together, and the grounding wires are pigtailed together connecting the switch and to the box, if metallic.The cable run from the light fixture requires a to-wire cable with ground. At the light fixture, completing the wiring is simply a matter of connecting the black and white circuit wires to the matching wire leads on the light fixture. The ground wire is connected to the light fixture lead and is pigtailed to the box, if metallic.
Can You Wire a 3-Way Switch Wrong?
Improper wiring is one of the most common problems that homeowners face when installing/replacing their 3-way switches. This occurs when the circuit wires are connected to the wrong screw terminals. It is very easy to accidentally confuse the wiring of a 3-way switch when you are doing a replacement at home.
Can You Use a 2 Wire for a 3-Way Switch?
If you only have a two-wire cable to work with, you can still be connect a 3-way switching circuit for your garage or hallway, to enable you turn a light on and off from two different locations. You can purchase a couple of 4-way light switches and a couple of silicon diodes (1N1344, 1N1614, or equivalent) and connect them. Two 4-way switches and two diodes wired back to back in a 2-wire circuit provide 3-way light control. If the light stays on regardless of switch position, reverse one of the diodes. Two 3-way switches, four diodes, and two wires also enable 3-way switching. Observe polarity. Different switch manufacturers may locate and wire switch terminals differently.
How to Diagnose a Bad 3-way Switch
Usually when a 3-way switch fails, you are able to toggle the lights on and off at one switch but not the other. If one of the two 3-way switches toggles the light(s) on and off, the other 3-way switch has probably failed. To diagnose a bad switch, follow these steps below: One of the 3-way switches will not turn the light on and off (while the light is on) and that is the bad switch. After identifying the bad 3-way switch, test to verify it is bad and needs to be replaced.
How to By-Pass a 3-Way Switch
If your circuit contains two 3-way switches, follow the instructions below to bypass: If the switch with the incoming “hot” is the one you want single control from: If the switch without the incoming “hot” is the one you want single control from:
Why would a 3-way Switch Not Work
There can be a number of reasons why a 3-way switch doesn’t work. Sometimes, one of the switches may have become defective. Also, someone may have tried to replace a defective switch and did not connect the wires properly. If the issue is a defective 3-way switch, it helps to replace both switches at the same time. The reasoning here is: say you have one switch that has failed, how much longer will it take before the other one fails as well? Besides, it can be tedious trying to determine which of the two switches has become defective. To replace a defective switch, first, you need to locate the common terminal. Once you do then follow these steps:
How Do You Fix a 3-Way Improperly Wired Switch
If your 3-way switch is not working it can be frustrating trying to figure out how to get it to work again. Chances are the problem lies with the wiring, which may have happened when changing a 3-way switch and not gotten the wiring put back together right. Fortunately, you may not need to call an electrician to have this resolved. Fixing an improperly wired 3-way switch can be a DIY assignment you can do on your own. For this, you will need the following things:
Philips head screwdriverFlat blade screwdriverElectrical testerWire nut
Then follow these steps to fix an improperly-wired 3-way switch:
How to Test a 3 Way Switch Wiring
To test for voltage, follow these steps: It is wise to also test the three colored wires in the other 3-way switch for voltage, if you haven’t already. There should not be any voltage, and you should not get a reading. If you get a voltage reading, this means that the switch is meant to control another light, appliance, or outlet. Maybe you are checking the wrong switch. To test for continuity, follow these steps: Usually there will be no continuity between the common terminal and one (sometimes both) traveler terminals of one of the switches when a 3-way switch fails.
How to Use a 3 Way Switch with a Light Dimmer
With a 3-way dimmer, you can control the light with two switches. You will need a 3-way dimmer and a 3-way switch. This lets you dim from one location and turn the lights on and off from another. If you are switching from two locations, you also need to use 3-way switches for both plain switches and dimmers. You can only have one dimmer per group. You can put the dimmer at either location, but not both locations. Follow the instructions below to install and use a 3-way switch with a dimmer: Remove the old switch
Installing a 3-way switch
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