Also, I just need to say this because it’s going to drive me crazy if I don’t (network engineer issue, sorry)
There are only a few brands of “Wi-Fi” light switches. Plum is one. But that’s not the lighting protocol that most home automation uses.
Instead, the entire category is called “networked” switches or “RF” (for radio frequency). Different protocols cannot talk to each other.
Lutron makes Excellent switches on their own proprietary RF protocol called “clear connect.” They also hold a bunch of patents, so most of the other RF device companies have to license some patents from Lutron. Lutron focuses on only one thing: lighting control. Their goal is a maximum of 500 ms before the lights come on, and they try to get it to 300 ms. They do have their own IFTTT channel and they do work with Apple HomeKit, so it’s not like they are completely independent of everybody else. They also have an open API so that some other companies like Logitech Harmony and Wink can include Lutron integrations. SmartThings has chosen not to directly integrate with Lutron.
After Lutron, probably the most popular protocol for RF switches is Zwave. Switches using the Z wave protocol are made by many different brands, including Leviton, Cooper, GE/Jasco, and GoControl. Home Depot, Lowes, and Best Buy will carry some so they are widely available. Different models have different features, but there are quite a few choices and they’re generally good switches. Like Lutron’s clear connect, zwave doesn’t use Wi-Fi, and like Lutron it also doesn’t get interference from Wi-Fi, so that’s good. Most SmartThings community members using switches probably have Z wave switches.
However, almost all zwave switches require that there be a neutral wire at the Switchbox. The neutral is used to power the radio so that the switch can hear the next “on” command from the network even if it looks like it’s off. (Lutron switches don’t require a neutral because of another one of their pattents that they have not made available to other brands.)
If there isn’t a neutral at the switchbox, you have some options, like “fishing up” a neutral from a nearby outlet, or using an in wall relay and putting it at the light fixture instead of replacing the switch, but it’s something to be aware of. And it may be that some of the switch boxes in your house have neutrals and some don’t, this is common for US houses built before 1980.
Another possible protocol is zigbee home automation (ZHA 1.2). The smart things hub supports both Z wave and ZHA, and there are some community members who have opted for zigbee switches. Like zwave, these will require a neutral wire. Unlike zwave and Lutron, zigbee can be drowned out by strong Wi-Fi. Sometimes you just need to move the device a foot or so to the left or right to avoid interference , which works fine for sensors, but not so much for light switches. . Many people, myself included, chose smart things because it can support both Z wave and zigbee devices – – but that doesn’t mean they use zigbee for light switches.
The general zigbee standard is popular in China so you can find a lot of cheap zigbee switches on international sites, but most of those will not work with smartthings because they are not certified for ZHA. Many use their own proprietary and coding and will only work with their own controller device.
There are a few Bluetooth switches starting to come out, but it’s hard for them to compete with the other protocols because they have much shorter range and they usually have to be paired to a phone. They’re OK for some very specific use cases, typically an outdoor light with a switch indoors in an inconvenient location, but I don’t know anybody using them as a whole house solution yet.
And, as mentioned, there are a few Wi-Fi switches, notably Belkin wemo and plum. These will also require a neutral wire. The Wemo are compatible with SmartThings. WiFi draws much more energy than clear connect, Z wave, or zigbee, so you get better energy savings if you choose one of the other protocols. Also, many Wi-Fi routers are limited to handling 30 to 50 devices, and if you start using those up for light switches then you may not be able to use them for your game players or tablets or laptops. If you use clear connect or Z wave or zigbee doesn’t affect your Wi-Fi at all, and while the total varies, most of them can handle many more devices then your typical Wi-Fi router.
So that was probably a lot of stuff you didn’t really care about, but it’s just an explanation of why most automated switches aren’t actually “Wi-Fi,” and that’s generally a good thing. . But it does mean you need to select your switch protocol with the pros and cons of each in mind, including which systems it can interact with.