3 Way Switches Explained – How to wire 3 way light switch


Hey there guys, Paul here from
TheEngineeringMindset.com. In this video we’re going to be looking at three way switches for lighting circuits in North America. We’re going to look at three
different circuit designs, depending on if you want to light fitting to be at the beginning,
the middle or the end of the lighting circuit. Now I’ve included a handy PDF wiring guide for this video with detailed illustrations of each circuit as well as step by step instructions and part
list for all three types. You can keep this guide
on your PC or mobile and access them anywhere at anytime. Links for that in the video
description down below. Now we’re covering the
theory in this video, but remember electricity is dangerous and can be fatal. You should be qualified and competent before carrying out any electrical work. So how do three way switches work? If we look at a three way switch we have four screw terminals. One is for ground, one
is our common terminal, and the other two are
our traveler terminals. Inside the switch we have a track which electricity flows along. This is connected to the switch handle. When we flip the switch handle, the track will flip between
the two traveler terminals. This will change the path
electricity can take, and that’s how we’ll control the light. The first circuit we’re going to look at is where the light fitting
is last in the circuit. For this circuit, we’re going
to need to following parts; some three wire cable,
some two wire cable, four wire connectors, a ceiling box, a light fitting, two three-way switches and two switch boxes. For the incoming power supply, we take the black hot
wire and connect this into the common terminal of switch one. We then run the black traveler wire from the left traveler
terminal of switch one and take this over to the
left traveler terminal of switch two. Then we run the black hot wire from the common terminal of switch two, over to the ceiling box
and into the light fitting. Then we take the red traveler wire and run that from the right
hand traveler terminal of switch one and take this over to the right traveler
terminal of switch two. Now for the incoming neutral, we run that into the wire connector which would sit within the
switch box for switch one. We then connect from this wire connector and run the white wire to a wire connector in switch box two. Then we run the final white wire from the wire terminal of switch two and take this over through the ceiling box and onto the light fitting which will complete the circuit. To provide some safety,
we run a ground wire from the incoming
supplier and connect this into a wire connector
within switch box one. Then we run a ground wire
from the ground terminal of switch one, and connect this to the ground wire connector. We connect the next ground wire between the wire connector
of switch box one, and the wire connector in switch box two. Then we run a ground
wire from switch box two, to the ground wire connector also. Finally as the ceiling box is metal, we will run a ground wire
from the ground screw in the box and connect this
to the ground wire connector in switch box two. So there we have a complete circuit with a two wire cable on
the incoming power supply, a three wire cable
between the two switches and another two wire cable from switch two over to the light fitting. Now if we power this circuit we see the electricity comes
in through the hot wire and passes across switch one and along the black traveler wire to switch two. The switch two is in the off position so the switch is broken
and the light is off. When we flip switch two,
the tracks change direction and electricity can now
flow across switch two, through the light and back
along the neutral wire. If we were to flip switch one, electricity can now flow across switch one and in to the red traveler wire but it stops at switch two as
the tracks are disconnected. But by flipping switch two we
again complete the circuit. The next circuit we’ll look at is where the light fitting
is between the two switches. For this circuit we’ll need
some two and three wire cable, five wire connectors, a
ceiling box, a light fitting, two three-way switches and
some black electrical tape. So from the incoming power supply, we will connect the black hot wire to the common terminal
of switch number one. Then we run the black traveler wire from the left traveler
terminal of switch one and take this over to the wire
connector in the ceiling box. Then we run another black wire from the wire connector and connect this into the left traveler
terminal of switch two. Then we run the red traveler wire from the right traveler
terminal of switch one and connect this to the wire
connector in the ceiling box. Then we run another red
wire from the wire connector and connect this to the
right traveler terminal of switch two. Now we bring our neutral wire in from the incoming supply and connect that into a wire connector within switch box one. Then we run another neutral wire and run this from the wire connector through the ceiling box and connect it into the light fitting. Then we run a third white wire from the other light fitting terminal and we run this to the common
terminal of switch number two. We must mark both ends of this wire with black electrical
tape to warn it is hot. Now to make the circuit safe, we bring our ground wire
into the wire connector. Then we connect to the
ground terminal of switch one and into the wire connector. Then we run another ground wire from the wire connector and bring this to the wire connector
within the ceiling box. As the ceiling box is made of metal we will need to connect
this to ground also. Then finally we want to ground switch two so we run a ground wire
from the ground terminal and bring that over to
the ground wire connector within the ceiling box. So there we go, a complete circuit where we have a two wire
cable on the incoming supply into switching box one and between both switches one and two and the light fitting we
have three wire cable. Now if we power the circuit we see that electricity
can flow through the hot, across switch one, through the ceiling box and to the terminal of switch two. But the circuit is broken at switch two so the light is off. When we flip switch two, electricity can now
flow across the switch, through the light and back
through the neutral wire. If we flip switch one, electricity will again be
able to make it to switch two by the red traveler but it
can’t get across switch two. But if we flip switch two, then we complete the circuit
and the light will turn on. The final circuit we’ll cover is where the light fitting is
before the two switches. For this type of circuit we’ll need some two and three wire cable, a ceiling box, some wire connectors, two switch boxes, two three-way switches, a light fitting and some black electrical tape. So for this circuit, we’ll
bring the incoming supply hot black wire into the ceiling box first and connect this into a wire connector. Then we run a white wire
from the wire connector and connect this into a wire connector within switch box one. We must mark both ends of this wire with black electrical
tape to warn it is hot. Then we run another white wire from the wire connector and connect to the common terminal of switch two. Again marking the ends
with black electrical tape. Now we run a red traveler wire from the right traveler
terminal of switch two and connect this to the
right traveler terminal of switch number one. Then we run a black traveler wire between the left traveler terminals of the two switches. From switch one, we connect a black wire from the common terminal and connect this to the light fitting terminal. Now to complete the
circuit we will bring our incoming neutral and connect this to the other light fitting terminal. To make the circuit safe, we bring our incoming ground wire and connect this to a wire
connector within the ceiling box. As the ceiling box is metal we will need to ground that
also using the ground screw. Then we run another ground
between this wire connector and another within switch box one. From there, we will connect
the switch ground terminal to the wire connector. And finally, we run a ground wire from the ground terminal of switch two and over to the ground wire connector. So there we have a complete circuit, with a two wire cable
for the incoming supply into the ceiling box. A two wire cable to the first switch and a three wire cable
between the two switches. When we power this circuit, electricity can flow through the hot wire and into the white wire
and over to switch two. Then it travels along the red traveler but stops at switch one. If we flip switch two, the electricity can now flow over and across switch two, then
through the light fitting and back through the neutral. When we flip switch one, electricity can’t make it past the switch, so the light is off. If we flip switch two, the
circuit is again complete so the light will turn on. Okay guys, that’s it for this video but if you want to continue your learning then check out one of
the videos on screen now and I’ll catch you there
for the next lesson. Don’t forget to follow us on Facebook, Twitter, Instagram and of course TheEngineeringMindset.com.

75 thoughts on “3 Way Switches Explained – How to wire 3 way light switch

  1. ⚠️ Found this video super useful? Buy Paul a coffee to say thanks: ☕

    PayPal: https://www.paypal.me/TheEngineerinMindset

  2. How a Photodetector works? How does it converts light into electrical signals? A video explaining everything about Photodetector will be nice if possible.

  3. Get the guidebook here: http://electricl.info/3-Way-Guidebook

  4. Honestly I've searched for years for air conditioning videos.
    I'm a technician learning on my own on the job.
    Your videos are literally putting food in my family's mouth.
    I cant thank you enough.

  5. One time, I wired five, 3-way switches, on the same circuit. After six shorts, I finally got it right. It drove me 10-times crazier.

  6. Travelers are called normally open, and normally closed. N.C. terminal is hot in the off position, N.O terminal is hot in the on position. Just a suggestion to explain things properly.

  7. I’m learning mechatronic and this is helping me a lot especially the 3 phase motors and all others electrical engineering. Can you also do more mechanical like misalignment, bearings, Gears, drive belt, sprocket And any other mechanical to help us all out I appreciate your hard work my sub and respect for you 💯

  8. What is the purpose of a 3 way Switch? As opposed to a standard switch?

  9. in canada, you dont need to ground the switch because it is in a metal box

  10. Please make more Electrical Engineering basics videos. The concepts in your videos are very helpful and easy to understand. Thank you!!!

  11. Just out of curiosity I'm still understanding the Code, by why exactly do we have to use a white wire marked with electrical tape instead of just using a black wire?

  12. So turning off the lights won't save electricity because there is a continuous current traveling to the switch?

  13. Could you make videos of boiler similar to the chiller series videos? Also really thank you for making these instructional videos. They are really helpful!!

  14. Paul, great content, thanks. Does your your three way guide book detail how to wire with multiple lights between two three way switches.

  15. this is the best explanation i can imagine! I had learned this years ago and needed a refresher. This was perfect! Thank you so much for your effort.

  16. When you have availabe time to making others tutorials create the video for 120V 60Hz american circuit with two 3 way switches and One 4 way switch

  17. Best explanation and diagram of a 3 way switch I've come across. The simplified animation really helps. Thanks for posting.

  18. Technically the second method and third methods are no longer legal. As per the NEC 2011 404.2(C), All switch boxes must have a Grounded/Neutral/White conductor in the box. Unless you want to spend the money on 4-Wire just wire it up using the first method. They did this due to the new presence of electronic switches. There are 2 exceptions, the first is if the box is attached to a raceway that could accommodate another wire, the neutral, at another point and not be a breach of their being too many wires in the conduit. The other exception is if the area behind the box is readily accessible without chipping away at the wall.

  19. Awww should have had the light setup where either switch can turn on the light & either can turn it off. Basically the flip of either switch, to either direction always reverses the status of the light.
    Those are fun 😀

  20. Excellent videos ; you may want to consider this Edison base lamp illustration , We should always show the hot wire to the center of said illustration the neutral should be connected to the shell in this Edison base lamp as we see in real life ….

  21. that’s the normal way of wiring a three way switch and it’s a good video. However if you have a wire missing there is another way it’s called a hot three-way give it a try . I could get you out of a snag with everybody but the inspector.

  22. Um actually you can’t use your white as a switch leg in the US. Per nec regulations in the branch circuits article, every device box must have a neutral for corresponding circuits or the capability of adding one if the raceway is a conduit rather than a manufactured cable

  23. I tired method #2 with 2 lights in the middle instead of 1. The functionality works but both lights are very dim, any ideas?

  24. Question about method 2. Because the neutral coming from the light and going into the second switch box is now re-identified as a hot, and there is no real neutral in that second box, is that a code violation? I know that all switch boxes need a neutral inside regardless if it’s used or not. Would that make the first method shown in the video the more common way?

  25. I have the following setup – switch 1, then 4 lights, followed by switch 2. I finally got everything working correctly, but the lights barely light up. It's as if there's a dimmer but it's not. I've been doing my own wiring for 20 years and never seen this. I didn't even know it was possible. What did I do wrong? Any ideas?

  26. This is by far the simplest and easiest to understand that even my 10 year old daughter would be able to do. Whoever gave this video a thumbs down, they’re probably the dumbest amongst dumb and the lowest of the low!

  27. Man you saved my day! I was going insane trying to figure this out on my own! thank you

  28. Absolutely one of the best and concise explanations of 3-way switching ! The animation is clear and efficient. Thank you!

  29. Question: First type: Light at the end. Why did white wire needed to be sliced in 3 pieces? Why couldn't it run directly to light without any caps?

  30. thank you so much for this vid. helped me feel more confident with my smart switch install.

  31. Awesome video explanation but the wiring in my house is so old that the solid core wires are all the same color beige!

  32. Question: what determines which of the three methods you would use?

    In an existing house, you might need to add an additional switch onto the end of an existing circuit, but what about a new build or a complete rewiring, where you are at liberty to decide what to do?

  33. Logically, the lightbulb experiences an XOR signal with the two switches being the inputs. Any additional switch can be added by XORing it with the lightbulb wire.

  34. I dont get it in all three cases both switches have to be on for power to travel through. Isn't it suppose to be one switch on or the other switch on to get power through? Am I missing something?

  35. Here in Spain we do not use as much exposed metal in our circuits. If asked for a 3 way light switch, the customer expects to see 3 switches, in other words 3 different switches controlling the same light.
    This enables us to wire between switches with 2 switch wires and the earth and neutral going straight to the light fittings.
    I can understand the reason for metal in your construction as you have more fire risk so an earth is essential to break the circuit.
    Most of our buildings are concrete block construction, so we use plastic back boxes.
    We call the switches 2 way switches, so in a 3 way lighting (3 switches) we use 2 * 2 way switches and one cross over switch.
    So one hot wire (live) goes to the first 2way and 2 transport wires to the crossover switch and 2 more transport wires from the crossover switch to the 3rd 2way then a grey switch wire (hot) to the light fitting.
    I hope that makes sense.

  36. There’s a problem with your payment method. I enter my card info but it says you can’t verify my card. I’ve tried it three times and I know all my info is correct. I’ve tried two different cards and I get the same problem. I’m using prepaid Visa cards because I don’t use my personal card numbers online. Could that be the issue?

  37. Sir: Both L-1 and L-2 use the GUY wire outside the property to return the unbalanced portion of the load, to the transformer. Why oh why is it not necessary to insulate this PORTION of the neutral while the inside portion
    it is necessary to insulate? Thank you for excellent past explanations.

  38. I never knew this. So how im able to turn my kitchen light off by 2 switches from opposite side of the kitchen one on each side and i can turn them on and off by either one so ig thats a 3 way? I live in 2002 construction

  39. By far the best video/instruction on how to wire 3-way switches that I have found. Thank you very much, you made this super easy and clear!

  40. I just wanted to say a huge thank you. Your video and .pdf file helped me troubleshoot and repair a three way switch in a stairwell that hasn’t worked correctly for 30 years.

  41. i have one switch for light A, another switch for light B, and one switch to control both. how do i wire this please

  42. This is the best 3-way switch explanation I've seen so far.
    I have a question though. How can I figure out which case is my current wiring setup on my 3-way switch with single bulb out of 3 case you've explained?

  43. As an electrician for the second method of 3 way switching we would normaly marr the black from the light box to the white of the 3 wire going to the second switch and use the black from the same 3 wire as the switch leg to the light fixture. This way there isn't two white wires attached to the fixture. Its a nit picky thing but that is how we do it in canada.

  44. Have you wire a 3 way switch on a ceiling fan using a 3 way multi switch where one toggles fan, one toggles light on fan and other
    Toggles a separate light

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