I am working as an electrician’s assistant, and I’m having a hard time conceptualizing how three- and four-way switches work. Why are they called three-way or four-way, and how does this affect their function? I just need someone to dumb it down for me!
In: Engineering
Not a native English speaker but a trained electrician. The three ways are really misleading.
Imagine trying to switch a light on from two diffrent switches in a way that it doesn’t matter which switch you use to toggle the lights.
This is done with a two three way switches. The tree way switch has one “input” and that one is connected to one of the two “outputs”. Switching does change which output is connected.
Now connect the power to one “input” and so you will have one live and one dead wire. The other three way switch is placed so that single end is connected to the lamp.
Using the switch on the lamp side makes you choose to connect it to the dead or the life wire. The power side changes which one is the powered one.
A for way switch switches them around when flipped and keeps them normal when not.
A normal switch has two wires – input and output. It also has two positions – on and off. Setting it to the on position connects the input and output, closing the circuit, and the off position disconnects them, opening the circuit.
A three-way switch has three wires – one input and two outputs, A and B (or one output and two inputs, if you reverse it). The switch’s position determines whether the input is connected to A or B. Take two three-way switches and connect their A’s and their B’s. Now, if both switches are in the same position, the circuit is closed, and if they’re in different positions the circuit is open.
A four-way has four wires – two inputs and two outputs. The switch determines which input is connected to which output. Now, you take two 3-way switches and one 4-way switch, and connect one 3-way switch’s A & B to the 4-way switch’s inputs, and the other 3-way switch’s A & B to the 4-way switch’s output. Now, each change of the switches will open or close the circuit.
[This Wikipedia page](https://en.wikipedia.org/wiki/Multiway_switching) has diagrams to demonstrate.
3 way switch is one input and two possible outputs. When you flip the switch you chang to witch output is connected to. The other output will not be connected to anything.
A 4 way switch has two input and two out outs. Let call the input a and b and the output x and y.
The switch has to state one where a-x and b-y are connected. when you flip the switch you change it so a-y and b-x are connected.
So input is always connected to output the difference it witch output
Look at the wiki page illustrations that show the idea with two 3 ways and one 4 way. You could add any number of 4 ways in the middle and it would work the same.
[https://en.wikipedia.org/wiki/Multiway_switching#More_than_two_locations](https://en.wikipedia.org/wiki/Multiway_switching#More_than_two_locations)
These are easiest explained with a pole diagram.
Trying to keep it clear:
A three way switches a common contact on the left between two out contacts right (single pole, double throw).
A four way switches two contacts on the left between opposite contacts on the right (double pole, double throw).
How you interconnect them depends on what you want to do.
https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcQbOZRlDRPzIiGwwLi3Rwo5IFVtd7dLeEAo0w&usqp=CAU
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