How does an electric circuit work where there are multiple switches? One light circuit in my house has four switches; three along a hallway and one downstairs. Using any switch either turns on all the lights or turns them all off regardless of other switches positions.
In: 4
That’s called “multiway switching”. Basically rather than opening/closing one wire like a regular circuit, there are two lines on the hot side (in addition to the neutral wire). Each switch swaps from one hot wire to the other. It’s easier to explain in a diagram (scroll down): https://en.wikipedia.org/wiki/Multiway_switching
https://mepacademy.com/3-way-switch-wiring-explained/
https://www.electrical101.com/3way-switches.html
The term is “3 way switch”. Google or YouTube search for “how does a 3-way switch work”.
There are multiple paths that the electricity can go through.
In your normal single-switch lightswitch, you have one input and one output. Your light switch either connects them or it doesn’t.
But then you have things called 3-way and 4-way switches.
A 3-way switch has one side with one electrical wire connected, and another side with two wires connected. There is always a connection through the switch to one of the two connections, and flipping the switch will flip it back and forth between connecting to the two wires on the other side.
A second 3-way switch on the other end takes those two output wires and does the same thing in reverse. Exactly one of the two wires is connected to the output on the other end.
If both switches are set to use the same wire connecting between them, then you have a completed circuit. If one is connected to wire A, but the other is connected to wire B, you don’t have a complete circuit.
Now if you want to add another switch into the mix, you need something called a 4-way switch. This will have two inputs and two outputs. It also has two connections made inside. Basically, there’s a connection from Input A to Output A and Input B to Output B, but if you flip the switch, then Input A switches to Output B and Input B switches to Output A. This means that this one switch, when in the middle of two 3-way switches, can toggle how they’re connected. At this point you can just add as many 4-way switches as you want.
Each switch switches between 2 lines
Switch 1 chooses whether your input goes to Line 1 or Line 2
Say switch 1 is powering Line 2
Switch 2 chooses which Line to pull power from
So if switch 2 is pulling from line 2 it will get the power that switch 1 is giving it, but if it pulls from line 1, there’s nothing giving it power
And it’s the same concept if switch 1 powers line 1
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Each switch controls the state of an SPDT (single pole double throw) switch. Each switch is wired to all of these switches and are wired up to control a light bulb. Basically when you close the switch, it sends current to the wires controlling the light bulb. If any of the switches are off, it closes the wire, allowing current to flow and turn on the light.
I can try to make a circuit diagram of this if it’s confusing.
But basically if any of the switches are on, it ceases the loop and the light doesn’t turn on.
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