Most smart switches are “momentary” switches rather than “bistable” like a regular dumb rocker or toggle.
A bistable switch has two fixed positions, usually up for on and down for off
A momentary switch rests in the neutral position. Usually you still press up for on, but then the switch immediately returns to the central resting position.
So the switch is always ready for the next command, whether it is manually at the wall or from the network.
If it’s a network command, then the switch doesn’t have to move at all, it just remains in neutral.
The following video of a Homeseer Switch happens to have a good close-up of the person’s hand so you can see how it works. But this is the typical method.
(ActionTiles.com co-founder Terry @ActionTiles; GitHub: @cosmicpuppy)
If using a “micro-relay” instead of a smart switch (… a micro relay is a convenient device you install at the Switch or at the target light fixture), then any change of the physical switch will trigger the State to change.
e.g., Say the light is OFF, but the physical switch is in what would appear to be the ON position; flipping it to OFF will turn the light … ON.
That’s because a micro-relay is really designed to work with a “momentary contact”, but conveniently also works in this sort of toggle configuration.
The micro-relay can also be triggered remotely by App or Automation - in this case, the physical switch doesn’t move (of course ), but remains available to be flipped for manual operation.
Micro-relays are an ideal solution for various situations.
If you want your smart switches to exactly match the physical style of your dumb switches.
If you don’t have a neutral line to the switch but you do at the fixture.
If you want to use a fancy “touch sensitive” glass panel as a switch (I haven’t seen many installations of these, but I presume they are popular in certain countries or high-end installations).
The action is similar, but they don’t latch into place.
This fact is why most manufacturers of smart switches only make rockers or momentary buttons, not toggles.
The toggle also rests in neutral, which means sticking straight out horizontally. It looks strange to many people, and they will tend to keep flipping the switch trying to get it to stay at the top or the bottom.
The rockers tend to be fairly shallow so it’s not really noticeable unless you look for it.