My first posting here. I am trying to add a Shelley2 dimmer in a 3-way or a 4-way switch to add dimming and smart switch capability because I do not have a neutral wire inside the box so I chose Shelley2 since Casa from TP-LINK required neutral for power. Any suggestions whether I add Shelley2 to a 3 or 4-way switch and sample wiring instructions ?
1 Answer
No-neutral smart switches that are not battery-powered typically don't work well with LED lights, since they power themselves and stay connected to the network by leaking current through the switch. Another issue with some of Shelly's devices is the lack of UL rating, which means they haven't been thoroughly safety-tested by the main US authority. Shelly 1 has UL certification but as of this writing Shelly Dimmer 2 does not.
That said, I found this wiring diagram from a European site showing the Shelly terminals and wiring for a 3-way. In this, you're basically repurposing the switches and travelers to just be signals for the Shelly switch detectors. Be sure to mark the wiring on the switches somehow to indicate this (typically colored tape is used).
Slight modification will be necessary to eliminate Neutral which is present in this diagram, and a Shelly Bypass may be necessary depending on the power present in the lighting circuit (more information in Shelly user manuals).
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1Wow, that would require dramatic rewiring. Definitely the most expensive way to do a 3-way circuit. Commented Dec 28, 2022 at 4:18