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How to Troubleshoot a 3 Way Switch (Simple Answer!)

by Lisa Hayden
How to Troubleshoot a 3 Way Switch

How to Troubleshoot a 3 Way Switch? Do We Know....

Do you have a big room that requires several switches? Or do you just love having more than one switch for convenience? Whether it is the former or the latter, you will be needing a three-way switch. This is a small but handy wall device that will make life easier for you.

What is a Three-Way Switch?

A three-way switch is a lot like your regular switches except that they come in pairs. Why? It’s because the purpose of a three-way switch is for you to be able to turn on or off your lights and ceiling fixtures from two different places. This means that if you can turn on a light on one end of the room, you can also turn them off on the other end. This is why you don’t see any on/off labels on the actual switch.

A three-way switch also has a bulkier body due to its screw terminals. It has a total of three terminals and a ground screw. Two of its screw terminals are connected to the other switch with wires. These are called traveller wires. The other screw terminal is usually connected to the ceiling or light fixture.

When to Troubleshoot a Three-Way Switch

what is three way switch

When do you need to troubleshoot a three-way switch? You don’t have to troubleshoot a three-way switch all the time. In fact, you don’t even have to do this regularly as this isn’t a software that needs updating and troubleshooting. However, there are times when your switches become defective.

A common instance when you need to troubleshoot is when the switches aren’t working. Of course, this presupposes that your light bulb is in good condition. If it is and the switches are not turning the lights on or off, then you have to troubleshoot. You may also notice just one of the switches is faulty.

Another instance is when the wires are not properly connected. Although you won’t know this unless you’re an electrician, a non-functioning switch can be brought about by wrong wiring.

How to Troubleshoot a Three-Way Switch

How do you fix a faulty three-way switch then? While you’re keen on fixing your three-way switch, you still need to be sure what the problem is. Is it a defective switch, or is it bad wiring?

Fixing a Defective Switch

To know if it’s a defective switch, you need to test both switches. Follow these steps to know which one.

1. Toggle the first switch. Turn the light on.
2. Toggle the second switch. If you can turn the light on and off with this switch, this means that the switch is working. Here’s a tip - a defective switch will not be able to control a light that is already on. Leave this second switch with the light turned on.
3. Now go back to the first switch. Turn it on and off. It works, then the problem is not a defective switch. Otherwise, that is the defective one.

wiring a three way switch terminal

Replacing a Defective Switch

When it comes to three-way switches, it is highly recommended that you replace the two switches at the same time. The reason behind this is that when one switch is broken, how much longer will the other one last? Since both of them were installed at the same time, then the other will most likely fail any time soon.

  1. First, turn off the power on the circuit breaker.
  2. Go to the three switches and remove them.
  3. When you are able to access the wires, make sure that they are not touching or are close to each other. If you don’t have an electrical background, you might get confused with the wires. To quickly identify each wire, you can mark them or add an identifier so that next time, you won’t get confused as well.
  4. Turn the power back on in the circuit breaker.
  5. You need to use a continuity tester for this part. Using this tool, check for ground on each wire. The ground wire is also called a “hot” or “live” wire since this is where the electricity flows. For a three-way switch, there should only be one live wire, and that is the common wire. If you found the live wire on one switch, there shouldn’t be another live wire on the other switch.
  6. When you find the live wire, go back to the circuit breaker to turn the power off.
  7. Install a new switch to the terminal with the live wire. Connect the live wire to the common terminal. Then, connect the traveller wires to the other two terminals. Close the new switch with all the wires inside.
  8. Now go to the second switch and then take off the old switch.
  9. Look for the common wire by touching one of the probes of the continuity tester to the wires. There should be a beep in one of those wires. The wire that beeps or registers a resistance is the common wire.
  10. Similar to what you did to the first terminal, connect the common wire to the common terminal. Then, connect the other traveller wires to their respective terminals.
  11. Attach the new switch to the wall with all the wires inside.
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Tips on Troubleshooting a Three-Way Switch

At first, troubleshooting a three-way switch seems like a daunting task. For people who have no idea about electrical wires and are uncomfortable with doing so, it’s best to call a professional. Sure, DIY seems the most economical thing to do, but if you are going to wire it or end up getting an electrical shock, it’s not worth it.

Another tip is to mark the wires. This is easily overlooked by people since it’s not that difficult to identify a live wire. However, you need to do this not just now but also for your future troubleshooting tasks. Even if you don’t mark the other wires, never forget to label the common wire. A coloured tape will suffice.

And that’s how you troubleshoot a three-way switch. It’s not that complicated, but you have to be extremely careful.

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