@gsuberland For plug loads: you use the switch built into the appliance

For overhead lighting loads: 3-position DPDT switch.

Pole 1: common = GPIO, top=24VDC (or other "logic on" voltage, bottom = floating/ground

Pole 2: common = light, top=relay output bottom=relay output

Up position: light wired to relay output, GPIO high. Normal state = GPIO controls relay through controller (but can also drive other relay loads or be switched on/off by other switches, HTTP requests, whatever)

Middle position: light forced off, regardless of relay state (optional: parallel the switch with a normally-open relay)

Bottom position: light forced on regardless of relay state

@azonenberg nah, I hate that. makes it hard to just reach for a light switch without thinking about it.