Two Way Switching Explained - How to wire 2 way light switch
video description
Date: 2023-11-17
Related videos
Comments and reviews: 30
adb012
What is the difference between the 2-way switch and the one-way switch with 3 termnals? They look identical in the video with the clap always connected to com and alternating between L1 and L2.
Also, what about the topology of 2 2-way switches with the light fixture in between, which is practical (but allowed) since normally the light is located between the 2 switches?
Connect both L1 to live and both L2 to neutral, then place the light fixture between the 2 comms. In this way when the 2 switches are en the same L both terminals of the light fixture will be on the same potential (either live or neutral) and hence no current will flow. When one switch is in L1 and the other in L2, then one side of the light fixture will be live and the other neutral. This configuration is the most practical, but has the obvious drawback that the light can be turned off by being on a live wire. When that happens it would be similar to having a light controlled by one normal one-way switch installed on the neutral with the live going directly to the fixture: The light may be off but the fixture still energized.
If this method is not allowed (because of the above or other reasons) I think it would have been good to point it out because it is not uncommon to see this installation (as it is not uncommon either to see switches on the neutral or outlets wired with reversed polarity.
reply
What is the difference between the 2-way switch and the one-way switch with 3 termnals? They look identical in the video with the clap always connected to com and alternating between L1 and L2.
Also, what about the topology of 2 2-way switches with the light fixture in between, which is practical (but allowed) since normally the light is located between the 2 switches?
Connect both L1 to live and both L2 to neutral, then place the light fixture between the 2 comms. In this way when the 2 switches are en the same L both terminals of the light fixture will be on the same potential (either live or neutral) and hence no current will flow. When one switch is in L1 and the other in L2, then one side of the light fixture will be live and the other neutral. This configuration is the most practical, but has the obvious drawback that the light can be turned off by being on a live wire. When that happens it would be similar to having a light controlled by one normal one-way switch installed on the neutral with the live going directly to the fixture: The light may be off but the fixture still energized.
If this method is not allowed (because of the above or other reasons) I think it would have been good to point it out because it is not uncommon to see this installation (as it is not uncommon either to see switches on the neutral or outlets wired with reversed polarity.
reply
education
All four setups are basically the same; Light is first or last (depending on perspective, 3 runners/travelers, com to com, L1 to L1 & L2 to L2 (straight thru) or L1 to L2 & L2 to L1 (cross over. 3 and 4 are identical, you could have used pink wire. Changing wire colour is not really a new circuit. Both 1 & 2 but not 3 & 4 are a change to where the live and light wires connect to either L1 or L2.
The real circuit types correspond where the light appear in the circuit, either at the start(power box at start and switches to rear, middle (hall with switch on either end) or end (high ceiling light in stairs. Power source is 2-conductor (Live, Neutral with Gnd, between switches 3-conductor (two Live, Neutral all treated as Hot with Gnd. Remember always run the neutral through the light and live/hot through the switches. You don't want to get zapped changing a light bulb.
reply
All four setups are basically the same; Light is first or last (depending on perspective, 3 runners/travelers, com to com, L1 to L1 & L2 to L2 (straight thru) or L1 to L2 & L2 to L1 (cross over. 3 and 4 are identical, you could have used pink wire. Changing wire colour is not really a new circuit. Both 1 & 2 but not 3 & 4 are a change to where the live and light wires connect to either L1 or L2.
The real circuit types correspond where the light appear in the circuit, either at the start(power box at start and switches to rear, middle (hall with switch on either end) or end (high ceiling light in stairs. Power source is 2-conductor (Live, Neutral with Gnd, between switches 3-conductor (two Live, Neutral all treated as Hot with Gnd. Remember always run the neutral through the light and live/hot through the switches. You don't want to get zapped changing a light bulb.
reply
Ed
I am OBVIOUSLY not an electrician. But I am an old (79) guy with lots of digital logic experience. I knew I could find the answer here, but I thought I should try to work it out for myself, a job I expected to take between 5 and 15 minutes. 40 minutes later, I still hadn't gotten my head around it. I even resorted to fooling around with truth tables and considering the various possible switch combinations and outcomes. I probably could have worked it out this way although maybe I would only have formalized the problem still without figuring out how to wire the darn switches. It couldn't be that complicated, and it's not. In fact, it is the sort of simple solution that we call elegant. But it is hard to get your head around it.
Thanks, Paul, for turning on the light for me!
reply
I am OBVIOUSLY not an electrician. But I am an old (79) guy with lots of digital logic experience. I knew I could find the answer here, but I thought I should try to work it out for myself, a job I expected to take between 5 and 15 minutes. 40 minutes later, I still hadn't gotten my head around it. I even resorted to fooling around with truth tables and considering the various possible switch combinations and outcomes. I probably could have worked it out this way although maybe I would only have formalized the problem still without figuring out how to wire the darn switches. It couldn't be that complicated, and it's not. In fact, it is the sort of simple solution that we call elegant. But it is hard to get your head around it.
Thanks, Paul, for turning on the light for me!
reply
Steve
Ok so this was helpful but didnt really answer the question I was hoping it would. Here goes. Bear with me. In my home we have a few of these lights that are controlled by two switches.
In most cases, if both switches are the same, either both up or both down, the light will be OFF. If the switches are mismatched (one up and one down) the light will be on.
My wife and I disagree about what is the right setup. She believes that the light should be ON if both switches are the same. I believe the light should be OFF if both switches are in the same position.
Is there a standard regarding this or is it just personal preference?
reply
Ok so this was helpful but didnt really answer the question I was hoping it would. Here goes. Bear with me. In my home we have a few of these lights that are controlled by two switches.
In most cases, if both switches are the same, either both up or both down, the light will be OFF. If the switches are mismatched (one up and one down) the light will be on.
My wife and I disagree about what is the right setup. She believes that the light should be ON if both switches are the same. I believe the light should be OFF if both switches are in the same position.
Is there a standard regarding this or is it just personal preference?
reply
Cranor
Great video, sat down and thought about how two way light switches work or may be connected. This video goes over it very well, but my final question after pondering on this before and after watching the video was, if these switches are far apart, isn't this a lot of wire work? Isn't there any simpler solution that would require less wire by the meter? Immediate thought is that you have another switch setup in between the two lightswitches but I imagine the reason for not doing that may be that simply running wires is cheaper/. less inclined to fail than another switch setup?
reply
Great video, sat down and thought about how two way light switches work or may be connected. This video goes over it very well, but my final question after pondering on this before and after watching the video was, if these switches are far apart, isn't this a lot of wire work? Isn't there any simpler solution that would require less wire by the meter? Immediate thought is that you have another switch setup in between the two lightswitches but I imagine the reason for not doing that may be that simply running wires is cheaper/. less inclined to fail than another switch setup?
reply
david
Hi Paul I installed downlights in my hallway, with a two way switch one at either end, after all plastering and paintwork completed I had to break open ceiling and walls which was heartbreaking, but this had to be done. I've used the option 1 from your vid, and works a treat, looks really well, I wouldn't have been able to do this without your very informative video with easy follow diagrams, thank you so very much for all in this case part of your knowledge. Keep up the brilliant work, now I've to go fill holes, thanks again.
reply
Hi Paul I installed downlights in my hallway, with a two way switch one at either end, after all plastering and paintwork completed I had to break open ceiling and walls which was heartbreaking, but this had to be done. I've used the option 1 from your vid, and works a treat, looks really well, I wouldn't have been able to do this without your very informative video with easy follow diagrams, thank you so very much for all in this case part of your knowledge. Keep up the brilliant work, now I've to go fill holes, thanks again.
reply
Stephen
While those four different versions are subtly different, they all assume you have room in the conduit leading to switch 1 for an extra three cores of cabling. What if the conduit for the original switch can't take an extra three cores of cabling? An alternative way to upgrade from 1-switched lighting to 2-switched lighting which requires room for only one additional core at the original light switch is to connect L1 to L1, L2 to L2, and importantly, to power the light from switch-2's common instead of from switch 1.
reply
While those four different versions are subtly different, they all assume you have room in the conduit leading to switch 1 for an extra three cores of cabling. What if the conduit for the original switch can't take an extra three cores of cabling? An alternative way to upgrade from 1-switched lighting to 2-switched lighting which requires room for only one additional core at the original light switch is to connect L1 to L1, L2 to L2, and importantly, to power the light from switch-2's common instead of from switch 1.
reply
Sokachin
Hi. Does current flow to an open circuited terminal when there is no electric field. Even if we look at it from a wave perspective, actual current flow only commences when an electric field is initiated. My fundamental understanding from college physics is that drift velocity of the electrons themselves is quite low in the neighborhood of 1mm/sec, however the electric field wavefront itself is almost same as speed of light. So why are you representing this as above.
reply
Hi. Does current flow to an open circuited terminal when there is no electric field. Even if we look at it from a wave perspective, actual current flow only commences when an electric field is initiated. My fundamental understanding from college physics is that drift velocity of the electrons themselves is quite low in the neighborhood of 1mm/sec, however the electric field wavefront itself is almost same as speed of light. So why are you representing this as above.
reply
tish
Excellent explanation. I'm trying to explain how to remove switch 2 to a friend and sent this video. Would it be fair to say to disconnect any connection to switch 2, tape off each of those wires and cap. Replace switch 2 with a wall plate. Then confirm supply at fixture is tied to Sw, if not remove old Sw2 connecr, tape & nut, then connect Sw1 supply to fixture. Replace switch 1 with a 2way (US) if necessary?
Sorry, I hope that made sense. Thanks for help.
reply
Excellent explanation. I'm trying to explain how to remove switch 2 to a friend and sent this video. Would it be fair to say to disconnect any connection to switch 2, tape off each of those wires and cap. Replace switch 2 with a wall plate. Then confirm supply at fixture is tied to Sw, if not remove old Sw2 connecr, tape & nut, then connect Sw1 supply to fixture. Replace switch 1 with a 2way (US) if necessary?
Sorry, I hope that made sense. Thanks for help.
reply
Darryl
Very helpful - a big thank-you. The only thing I don't understand is why you'd use the 4 more complex versions of the connection in place of the basic version.
EDIT: I answered my own question: it depends on the position of the live and the load - in the basic case the live comes into one switch while the load is connected to ther other switch. In other cases, the live and load might both come into one switch, hence the variations.
reply
Very helpful - a big thank-you. The only thing I don't understand is why you'd use the 4 more complex versions of the connection in place of the basic version.
EDIT: I answered my own question: it depends on the position of the live and the load - in the basic case the live comes into one switch while the load is connected to ther other switch. In other cases, the live and load might both come into one switch, hence the variations.
reply
Dolphiweb
The V1 is the most simply and most used everywhere, the others V2, V3 and V4 are needlessly complex, only a mad electrician would use 'em. Also, if you need to add a third o more positions where to switch the light on and off by using a four way switch, they'll need to rewire the whole thing in V1 way which makes the V2, V3 and V4 impossible.
reply
The V1 is the most simply and most used everywhere, the others V2, V3 and V4 are needlessly complex, only a mad electrician would use 'em. Also, if you need to add a third o more positions where to switch the light on and off by using a four way switch, they'll need to rewire the whole thing in V1 way which makes the V2, V3 and V4 impossible.
reply
Justin
On the 1st set up with the live going into the com of the 1st switch and the live out com of switch 2 to the light can you line up L1 with L1 and L2 with L2 instead of switching them like you showed in the video? I thought that is what you were going to do and don't see why it would make a difference especially with AC but idk for sure
reply
On the 1st set up with the live going into the com of the 1st switch and the live out com of switch 2 to the light can you line up L1 with L1 and L2 with L2 instead of switching them like you showed in the video? I thought that is what you were going to do and don't see why it would make a difference especially with AC but idk for sure
reply
education
Thank You for your simple explanation. L1 to L2 and the common to common did the trick for me. I had wires in the walls and you helped me more than any other video. Well done my-man. after this I won't need to watch another video again. have many times over the years. You are an incredible teacher
reply
Thank You for your simple explanation. L1 to L2 and the common to common did the trick for me. I had wires in the walls and you helped me more than any other video. Well done my-man. after this I won't need to watch another video again. have many times over the years. You are an incredible teacher
reply
Joe
I don't know why you would suggest using brown, black and grey wires without mentioning that in the real world this would be a 3-core and earth cable. You wouldn't be using singles in a domestic installation unless there was existing containment for them, which would be very unlikely.
reply
I don't know why you would suggest using brown, black and grey wires without mentioning that in the real world this would be a 3-core and earth cable. You wouldn't be using singles in a domestic installation unless there was existing containment for them, which would be very unlikely.
reply
andrew
What do I do if I shut switch one off, but the light stays on until I turn switch 2 off. and vice versa
I can turn the light on with either switch, but if I try to shut it off with the other switch it stays on unless I go to the original switch I used and shut that one off
reply
What do I do if I shut switch one off, but the light stays on until I turn switch 2 off. and vice versa
I can turn the light on with either switch, but if I try to shut it off with the other switch it stays on unless I go to the original switch I used and shut that one off
reply
Joe
Ive got 2 lights and 2 switches needing fitted in a garage. To add the 2nd light do i just take a link from the first light to the second? At 2. 44, basically with another Live and neutral to the next light?
reply
Ive got 2 lights and 2 switches needing fitted in a garage. To add the 2nd light do i just take a link from the first light to the second? At 2. 44, basically with another Live and neutral to the next light?
reply
forthoseabouttodie
An excellent, simple graphic. That should help anyone who has any problems with understanding the setup.
Could you also show the setup with double/treble light fittings?
reply
An excellent, simple graphic. That should help anyone who has any problems with understanding the setup.
Could you also show the setup with double/treble light fittings?
reply
Anup
I used two way switch for Fan. when i press two way switch button then socket plug get affected. whatever I plug into that socket, its get off and start again.
What is the issue?
reply
I used two way switch for Fan. when i press two way switch button then socket plug get affected. whatever I plug into that socket, its get off and start again.
What is the issue?
reply
Daniel
I was able to practice all the versions successfully and I must say all of them makes supply available to them switches in case you need to loop a feed or live for fan
reply
I was able to practice all the versions successfully and I must say all of them makes supply available to them switches in case you need to loop a feed or live for fan
reply
Abubakar
I want learn more about switch control. 2 switch control 1 bulb, 3 switch control 1 bulb, 4 switch control 1 bulb, 5 switch control 1 bulb, 6 switch control 1 bulb
reply
I want learn more about switch control. 2 switch control 1 bulb, 3 switch control 1 bulb, 4 switch control 1 bulb, 5 switch control 1 bulb, 6 switch control 1 bulb
reply
Ramon
This helped me enormously, I did it twice! Before I discovered that lamp supplier had delivered 24 V lamps not 240 V lamps. Your wiring works perfectly! Thankyou
reply
This helped me enormously, I did it twice! Before I discovered that lamp supplier had delivered 24 V lamps not 240 V lamps. Your wiring works perfectly! Thankyou
reply
Dharm
Why doesnt it short when the Live connects to L2 and the switch is on so current is flowing form L2 Swith 1 to L1 Switch 2 and looping through Com 1 and 2?
reply
Why doesnt it short when the Live connects to L2 and the switch is on so current is flowing form L2 Swith 1 to L1 Switch 2 and looping through Com 1 and 2?
reply
LDE
Why when light is off, my first switch is in on position and second switch is in off position? How to make both switch in off position when lights are off?
reply
Why when light is off, my first switch is in on position and second switch is in off position? How to make both switch in off position when lights are off?
reply
StarChild
i was thinking about how this works all day and couldn't figure it out, i can't believe it's this simple
i'm going to build this in minecraft
reply
i was thinking about how this works all day and couldn't figure it out, i can't believe it's this simple
i'm going to build this in minecraft
reply
Artofmen
thank you.
first presentation is like XOR gate
then
version 1 - XNOR
version 2 - XNOR
version 3 - XOR
version 4 - XOR
reply
thank you.
first presentation is like XOR gate
then
version 1 - XNOR
version 2 - XNOR
version 3 - XOR
version 4 - XOR
reply
Zaid
Great video! A three way switch in America is one where you can wire two applications into one switch with the middle position being off.
reply
Great video! A three way switch in America is one where you can wire two applications into one switch with the middle position being off.
reply
Egod
Regarding the disclaimer, how does someone become qualified and competent? Is there somewhere in the website I should start with basics?
reply
Regarding the disclaimer, how does someone become qualified and competent? Is there somewhere in the website I should start with basics?
reply
David
Thanks for this video! It allowed me to figure out and fix why I could only use one switch for my living room fan and stairway light!
reply
Thanks for this video! It allowed me to figure out and fix why I could only use one switch for my living room fan and stairway light!
reply
SID
My dad did this and as kids wed have hours of fun. Still working after 50 years. I could never understand how it worked.
reply
My dad did this and as kids wed have hours of fun. Still working after 50 years. I could never understand how it worked.
reply
Awais
In uk the neutral, live and earth all enter each fixture, like you've shown it in the thumbnail. How does that work?
reply
In uk the neutral, live and earth all enter each fixture, like you've shown it in the thumbnail. How does that work?
reply
Add a review, comment
Other channel videos
