With most smart lighting devices, the switch needs to be powered on continually in order to have the ‘smart’ ability available – and the Sonoff is no different.
One thing that is different, however, is that the power on state has 3 distinct options which are selectable . Typically the power on state cannot be changed on many systems. Each option is described in detail :
1) ON : As per video, this is the option I prefer. This means when power is restored for whatever reason, the bulb defaults to on. Effectively, this means the switch can be used as a traditional switch with the lever. A negative, though, would be a power cut in the middle of night and having your house default to on …
2) OFF : This is the default setting and means that the lever can’t be used traditionally. If power is cut and restored, everything remains in the off state.
3) KEEP : This means that when power is restored, the lights go back to what their previous settings was. Lights that were on, go to on – and off, go to off. A great thing with the options is that each light can be set individually.