Hi - I’m doing some rewiring and got to thinking about this. Latest NEC code requires all junction boxes (JBs) to have a neutral in them, but does not require a live. In the case of a two way switch you’ll have both neutral and live in your JB by default. But for a 3 way switch you’re likely to end up without live in one of the JBs. Can smart switches deal with this? To be clear - one of the travelers for the 3 way/4 way would always be hot - but it would toggle between when is hot and which isn’t as the switch gets toggled.

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Thank you!

  • Unable-University-90@alien.topBEnglish
    1·
    1 year ago

    It’s all over the map depending on the product line. As Engineers-rock pointed out, there are product lines that allow one switch wired into the circuit and everything else has to be battery-powered remotes. (Which in the case of Lutron Caseta look almost exactly like their switches and can be mounted on a wall behind a switchplate.) One nice feature is that you can directly pair the remote with a switch, so it works even if your hub is offline, assuming the remote and switch are close enough to each other to communicate directly.

    Another product line you might want to look into is the Jasco/GE Embrighten switches. They make “Add-on” switches that work with their smart switches that can be wired in a box with neutral and 2 travellers coming in from the smart switch’s box. If you look at the wiring diagram (https://byjasco.com/media/manuals/46200-QSG-v1.pdf) you’ll realize that the add-on switch is not actually switching anything, but is acting as a remote for the smart switch, while being powered by the smart switch.

    There are other switches, an example, I believe, are the Aqara switches, where you’re expected to integrate the switch and button of your choice with a hub and the whole affair is the lowest common denominator “have something happen; have hub tell switch to switch” that should work with any smart switch.

    For the sake of completeness, I’ll mention that many (most?) smart switches will work with the existing 3-way switches so long as you put the smart switch nearest the breaker (so it always gets power on the terminal it expects to). See https://help.inovelli.com/en/articles/8269832-red-series-dimmer-switch-wiring-schematics for Inovelli’s instructions for doing that with their Red Series devices, as an example. The user experience may vary, however.