Documenting the process to add shelly relays to my home lights.
- Confirmed lights for Living/Kitchen/Hallways connect to one 15A marked breaker
- Removed triple switch light panel to look at light switches.
- I see each switch has two black wires and one ground, with the rocker switch itself being marked with 120V-277VAC
- Closer inspection revealed neutral wires bundled in the back
- The first switch (hallway light switch) also has a red wire, which appears to be a traveler wire to another switch down the hall, making this a three way switch
- Missing wire nuts and 14 gauge wire (15A rated wire) to perform the install today
Summary of research I did a couple days ago (pure recollection):
- Three way switches come in two forms traditionally, one is where you have live (L) traveling from breaker to S1, which then travels to S2, which finally travels to the light. The other is when L goes to S1 & S2 and travel to light (think of light in the middle and switches on both side), however I’m less sure of this configuration and only mention this from the pictures I’ve seen, but unclear if this is how it works.
- I looked into the first configuration, and that one makes the most sense to me. I think of it as a railway track that spilts into two parallel railway tracks and then again combines back into a single one. So a railroad switch on both ends of parallel railway tracks. You have two operators responsible for each switch, on one end the operator is responsible for guiding an incoming train into split 1 or split 2, on the other you have an operator who accepts incoming trains from split 1 or split 2 into the destination. If an operator routes the train into split 1 but the operator at the other end only accepts traffic from split 2, then the train will not reach it’s destination. This means the operators need to have synced positions of the two switches to route the train to the destination. Accordingly to stop the train from reaching it’s destination, you only need to flip one switch to get it of out sync, which switch that is doesn’t matter.
- So one solution to wire a relay into this setup is to remove the switch from one end, and then you can wire up the relay like normal. This will mean that one switch no longer works.
- To get both switches to work, you take the switch you’ve remove from the circuit and wire it to it’s own relay, but don’t have any ouputting circuit for that relay. Then in software, when you receive a signal from the relay without an output, you setup an automation to flip the output of the relay with the output.