Sure, any switch that the hub can talk to can be put on any circuit, or even a battery operated device, and then you can use it to control anything else that the hub talks to.
Cooper has a battery-operated wall switch that a lot of people like the look of. But if you have a available switchbox and you want to wire something in you can use any switch that is smartthings compatible and that switch can talk to the hub, and then the hub can talk to any of your other devices. They don’t have to be on the same circuit.
