I have an average understanding of electrical wiring so forgive me if my question might seem vague to you. I have two switches in my house, one is an Insteon SwitchLinc and the other one is a single pole switch (I believe). I'm excluding the ground wires from the explanation.
The Insteon SwitchLinc has 3 wires, a red, black, and white (and a ground attached). The single pole switch has two gold connectors (and a green).
There are two Romex gray wires, one is a 12/3 with ground. The other is a 12/2 with ground.
The red wire from the 12/3 is connected to the bottom terminal of the single pole switch.
The Insteon SwitchLinc red wire is connected to the 12/3 black wire and the black wire is connected the the 12/2 black wire.
Hopefully the diagram below illustrates what I am describing. The Insteon turns on an outside light but I can't figure out what the single pole switch is doing. It has no effect on the light and doesn't turn off any other light in the room. There is an outlet near the baseboard in line with the switch. That particular outlet has 3 sets of black and white wires all connected to it. I also plugged in a light to each outlet (top and bottom) and the switch had no effect.
Can someone explain and help me understand what the purpose could be based on this wiring or could this be incorrectly wired?