Because it’s cheaper, easier, safer, and more reliable to just power the switch from the circuit it’s controlling. And generally NOT a good idea to put batteries inside a closed box with a live circuit that has extended wiring. It’s possible for fire to travel along the wires inside a wall. So a battery device is usually kept separate from those wires, just in case.
The only reason we have a use case is because we want to keep the radio powered while the circuit itself is off. That’s so the radio can hear the next “on” command from the network.
It’s possible to do that without using batteries, in fact it’s quite easy if you only want to control incandescents. That’s how the old GE switches worked, and it’s how the current Cooper models work that don’t require a neutral. It’s just tricky for other engineering reasons if you want to control LEDs or CFL’s.
As with many other light switch issues, the Lutron company has poured a ton of time and money into research on building better light switches, and they do have a modern RF switch, the Lutron Caseta, which can control LEDs and doesn’t require a neutral. It’s actually some pretty amazing engineering. But it’s also patent protected, and not available to other companies. And of course it still doesn’t solve the issue for people who are not allowed to replace a light switch. It’s not battery-operated, and it doesn’t work with SmartThings directly.
So if you don’t want to replace a light switch, regardless of the neutral wire issue, you have the following choices:
One) use a smart bulb, put a switch lock on the existing light switch, and use any of the several battery-operated choices for controls which do work with SmartThings. I personally really like the smartenIT 3 toggle switch, but there are other options as well.
Two) wait six months until the switchmate, or some similar competitor, is available. This is a Bluetooth switch that fits over the existing switch, very similar to how the August lock works.
I’m very impressed by the early engineering specs on this, and it’s one of the very few devices that I have supported early in a kickstarter or indiegogo campaign. It’s available now for preorder, but it’s still several months away from shipping.
This is going to be kind of ugly, it’s a big box that fits over the existing switch. And there’s no telling exactly how or if it will integrate with SmartThings until The Bluetooth radio is actually turned on in V two and the switchmate is actually shipping. But it’s a no wire, battery operated mechanism that will operate an existing switch. (Notice, though that the battery device is not going inside the switchbox where the live wires are.)
- If you’re handy, you can build your own switch toggle which is a mechanical device that literally just flips a switch on and off. They’re not that hard to build, but they are ugly. Then you need to add a thingshield to it so that they could talk to SmartThings. And of course you would need one for each switch. so that’s another possibility if you really need something right away. But I think most people would choose option one instead of this.
Those are pretty much the only three options that don’t require doing something with the existing wiring. And one of them is still in pre-release development.