I just installed an MS-OPS2H-WH switch. The light was on by default when I switched on the circuit breaker. Is this normal? I didn't want to try pressing the button because I blew a switch doing so yesterday, although that was a different problem. I called the technical support and he told me that this is a common problem with the ground, but I doubt it. My condo is built in San Jose in 2013 and the switch is on the ground floor. If I don't have a good ground, I doubt anyone does, unless my wires were not twisted together properly.
The other thing I'm concerned about is that I have 3 sets of black, white, and ground wires in my box. I know one of them is the load and one of them is the hot, but I'm not sure what the other one is. The only time I can detect a voltage with a non-contact detector on this wire is when I turn on a specific light in the room next door. Right now I'm connecting this 3rd black wire to hot and it doesn't seem to have any adverse effect on any lights, I'm just worried that something bad might happen when I press the button on the switch. Unfortunately I didn't pay attention to how the original switch was wired so I don't have a reference. Is there anything I can do besides guessing and calling an electrician?