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.
Except, of course, in the case of houses with no neutral, of which there are clearly a lot – in that case, it’s impossible unless you allow a tiny load through the circuit at all times, as you mention:
But, of course, incandescents are obsolete tech – why would I want to use them, even if I could buy them illegally somewhere?
Really? This is a thing? You can’t have tiny Li-ion batteries in proximity to house wiring? Maybe this is the actual answer to my long-standing question. Just curious, though: how does the Caseta get away with it? Or my alarm company, which has a honkin’ big battery right in the powered switchbox?
Thanks for mentioning this – I hadn’t heard of it and it’s a tricky one to find. Googlers, look for Smartenit ZBWS3B.
I still don’t feel like my question has been answered; as an engineering challenge, this feels completely basic. Unless, as you say, there’s some fire code thing with the battery being near a wire.
I was looking for a battery powered z-wave input module and found this discussion.
I agree with Graham Charles totally.
Looks like no one has an answer - as there should be one!
And there is one - but why so rare I don’t know
Found this at Home Depot yesterday: Lutron Connected Bulb Remote
Says Wink Hub required, but the package and Lutron indicate it’s Zigbee (not on the web listing). The description says it controls Cree and GE Link bulbs directly, and the spec sheet says the same generically – I didn’t know Zigbee could do that, can someone explain how to set that up - maybe that’s what you need the Wink hub for?
Previous Lutron products used their proprietary Clear Connect system, which Wink had support for, but this one seems to just be Zigbee, so it seems like it should work with SmartThings. My current use-case is well-served by the controller I hacked together from a key-fob and mechanical buttons, but I’m tempted to get this if it can provide easier dimming control.
I am late to this thread, but couldn’t agree more with grahamcharles. This would be very useful piece of hardware since it allows people that aren’t as interested in using the apps or even Alexa to use a good old fashioned switch in an old house with no neutral.
Just basically be able to trigger a scene in ST. So keep the ideas coming cause i am still looking for a good solution to this.
There is now an official integration with smartthings and Lutron Caseta. These are wired switches that do not require a neutral. However, you will need the Lutron smartbridge as this is a cloud to cloud integration.
There’s also a Leviton zigbee wall switch which does not require a neutral and is on the official “works for SmartThings” compatibility list, but I haven’t heard of anybody actually using one and it’s an expensive switch, around $85 each. But it is another option and it doesn’t require an additional bridge device.
If you were looking for a battery powered switch to communicate with a smart bulb or a micro relay at the ceiling fixture or to create a virtual three-way with another smart switch, see the following:
So there are now several different ways to address the issue of a switch box that doesn’t have a neutral.
Works well, people like it. One Lutron SmartBridge can handle several dozen switches. So it does meet the need for many people. It would be expensive if you only needed one switch, but once you get up to four or five it’s comparable to other choices.