A three-way switch that keeps state with the other switch [closed]

Question

Is there a three way switch that will physically change the state of the other switch so it's in the updated position?

Let's say both switches are physically off, and the light is off:

 |---------|     |---------|              
 |         |     |         |           _____      
 |  |---|  |     |  |---|  |         /       \
 |  |   |  |     |  |   |  |        (         )
 |  | x |  |     |  | x |  |        ( ))))))) )    
 |  |---|  |     |  |---|  |         \ \   / /
 |         |     |         |          \|___|/
 |---------|     |---------|           |___|     
                                       
  Switch A        Switch B            Light
  OFF pos.        OFF pos.            OFF

Then we switch Switch A ON and the light comes on. Traditionally one might expect the light to turn on, and Switch B to stay in the OFF position:

 |---------|     |---------|             |
 |         |     |         |     \     _____     /
 |  |---|  |     |  |---|  |         /       \
 |  | x |  |     |  |   |  |        (         )
 |  |   |  |     |  | x |  |    -   ( ))))))) )   -
 |  |---|  |     |  |---|  |         \ \   / /
 |         |     |         |          \|___|/
 |---------|     |---------|      /    |___|    \
                                       
  Switch A        Switch B            Light
 -ON pos.-        OFF pos.           -ON-

But this configuration has a drawback: I can't look at or feel either switch and know what state the light is in. Also, each time I go to flip the switch ON, I have to look and see if I should flip it to the ON or OFF position.

I know these seem like tiny issues, but add in the time you spend wishing these switches were designed better, then multiply that by the million times in your life that you flip a house switch.

In my ideal world, the unmanned switch (Switch B) would flip itself up to the ON position, to accurately reflect the actual state of the light:

 |---------|     |---------|             |
 |         |     |         |     \     _____     /
 |  |---|  |     |  |---|  |         /       \
 |  | x |  |     |  | x |  |        (         )
 |  |   |  |     |  |   |  |    -   ( ))))))) )   -
 |  |---|  |     |  |---|  |         \ \   / /
 |         |     |         |          \|___|/
 |---------|     |---------|      /    |___|    \
                                       
  Switch A        Switch B            Light
  ON pos.        -ON  pos.-           ON

Does such a thing exist or will I need to invent it?

Answer 1

To clarify: are you talking about an actuator in each switch, that mechanically flips the other one into the same position? This particular product I'm not aware of (although it may exist, I haven't found any).

I would suggest going the IoT route instead, and mate several RC switches to the same light (you additionally insert a small control unit into the wall/ceiling socket to make this work).

There are product lines that provide an indicator light as feedback that would be visible on both switches once the light is on (a system with two way communication is required though). Random example (there are many):

Answer 2

Don't invent something. It's already obsolete.

This problem has been eclipsed by smart switches, as MiG covers fully.

Naturally, just like in modern cars, the trend is to eradicate actual physical controls, and make them virtual.

However, if you wanted to do this, let's briefly survey the marketplace of what already exists.

The classic GE "RR7" system.

You may have been in a commercial building and found a switch in the center position. It is momentary in both up and down positions - that is, it springs right back. What's that about?

It is sending a momentary pulse (for as long as you hold the switch) to a latching relay. The relay throws over to the "on" or "off" position, and stays there after you let go. And that's it. There is no limit to the number of switches, and "up" is always on, and "down" is always off.

Granted, this does absolutely nothing to tell you whether the light is on. The RR7's win is to remove the control uncertainty of normal 3-ways, and allow you to positively set the light's condition with the same hand movement everytime.

It's low voltage, so it uses simple thermostat style wire. If you needed an indication, you would simply wire an indicator device (light or noise maker e.g. fan) in parallel with the lights. This could be a low voltage transformer powering an indicator at the switch, meaning it could simply be a 4th wire in the low voltage cable going to each switch.

Plain old 3-ways with indicators

The other option is to run /4 cable between the switches, and arrange the wiring such that the 4 wires are 2 travelers, switched-hot, and neutral.

Now, at each switch, an indicator light or device can be powered from the switched-hot and neutral.