I’m sourcing z-wave parts currently and discovered this Vision z-wave switch ZL7431US light switch has Single Pole Double Throw (SPDT) relay:
User manual doesn’t say anything about relay contacts, but I cracked one open and determined all relay contacts are made available and wired as follows:
- Relay Normally Closed (NC) ----- YELLOW wire
- Relay Common (COM) ----- RED wire
- Relay Normally Open (NO) ----- BLUE wire
The relay itself is Song Chuan’s 892HN-1CH-C. Its coil consumes 200mW according to datasheet, which can be googled easily. I’m pretty sure these relay contacts are isolated so you can switch currents running on different power plane.
The BLACK and WHITE wires are obviously for 120VAC, Hot and Neutral respectively.
And then there’s this GREEN wire used as an external control line. (NOTE: I only tested below in the “01” configuration, which is “To control Light with 1 or 2 Wall Switches” configuration. It was the default setting according to my manual. I suspect the meaning of Green line will change in “02” configuration.)
- If GREEN wire is left floating open (i.e, not connected to anything), the Z-wave controller interpret ‘On’ state as switching the relay on (i.e., Com connects to NO), and ‘Off’ state as switching relay off (i.e., Com connects to NC).
- If GREEN wire is connected to 120VAC Hot, the meaning of ‘On’/‘Off’ state flips - now ‘On’ state will turn off relay (i.e., Com connects to NC) and vice versa for ‘Off’ state.
So this GREEN wire can be connected to a ‘manual override’ switch when you have z-wave connectivity problem and you can’t toggle through the hub, which is perfect for pool valve control.
