I'm trying to upgrade some light switches to smart switches that require neutral wires. I did a couple single pole switches months ago which, with some trial and error, worked fine. I'm stuck on at least one 3-way.
The house was remodeled in 2005, so there are neutral wires. However, the 3-way switch I'm currently trying to change is housed in one double-gang box (Box 1, Switch #1) and one single box (Box 2, Switch #2). In the double-gang box, the other switch (Switch #3) is controlled by a different breaker.
The 3-way switches in both boxes 1 and 2 use a white wire as a traveler, which leaves me without a white neutral wire for the smart switch.
Initially, I thought Switch #1 was the input because it's the main (most accessible, most used) switch. However, after realizing that Switch #3, right next to it, is on a different circuit (signifying the start and end of a circuit?), I suspect that Switch #2 is the input. Please correct me if I'm wrong and/or if there's a way to verify that.
So far, I've tried:
- Box 1: pigtail power from Cables 2&3 (Box 1) to the line/load on the smart switch (using red & black as travelers, white as neutral)
- Box 1: pigtail from the neutral bundle (Cables 1,2,3) to the neutral on the smart switch (maintaining the white and red as travelers)
- Box 2: Pigtail power from the black bundle (Cables A&B) to the line/load of the smart switch.
Please let me know if you need more information or if my pics/illustration need clarification.
An extra credit question is: how do I know which neutral wire to use when changing out switch #3 (Box 1), given that wires from Cables 1,2, and 3 are all employed for that single switch?
Products I'm using are Treatlife 3-way smart dimmer switch and TP-Link Kasa Smart Wifi Light Switch Dimmer (as titled on boxes)