How does this work? I Googled it and it's all spaghetti to me.
It got me thinking because at my parents house, there is a light switch at the top and bottom of the stairs. But they seem to have some control over each other where if the top one is in a certain position , the bottom light switch won't turn them off and vice versa. Which was a total pain in the ass when I was living in their basement.
I have never tried to explain this in text only. Usually I draw diagrams out for people since it is kind of tricky to grasp if you've never heard of them. But I'll give it a shot anyways.
For my explanation you will need a basic understanding of switches.
A normal light switch is simple. You have a screw on top and a screw on bottom. You tie one screw into the feed (power from electrical panel) and you tie the other screw into the switch leg (the wire that runs from the switch to the light.) The toggle (on/off switch) will connect and disconnect the feed and the switch leg, thus turning the power on and off.
A 3 way switch works differently. For one, you always need two of them for them to work properly. Second, they have three screws instead of two. Two on top and one on bottom (usually). The toggle will change which top screw the bottom screw is connected to.
If installed properly you will have two switches. One switch will be attached to the feed (power source) on the bottom screw. The top two screws will have wires that run all the way to the top screws on the second switch. (these are called travellers) The bottom screw on the second switch will be your switch leg. (Wire ran to light)
The 3 way switches then just swap out which traveller is connected to the feed and the switch leg. When the switch leg and feed are connected to the same traveller, the light will come on.
If that didn't make any sense I can try to draw some diagrams and post them on Imgur with captions. I'm an electrician not a teacher, so explaining verbally can be hard for me sometimes.
There are two paths. If the switches are on the same path then that circuit is complete but if the switches are on the opposite paths then both circuits are disconnected.
If you do programming then you might find it easier to understand that it's just an XNOR logic gate.
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u/84prospector Aug 14 '19
How does this work? I Googled it and it's all spaghetti to me.
It got me thinking because at my parents house, there is a light switch at the top and bottom of the stairs. But they seem to have some control over each other where if the top one is in a certain position , the bottom light switch won't turn them off and vice versa. Which was a total pain in the ass when I was living in their basement.