In the Blue series project discussion thread, Eric mentions a firmware change regarding the use of the mechanical relay when in Single Pole, On/Off, neutral mode:
What I got out of that was that originally, when in Single Pole On/Off mode, the switch was a dimmer switch, but the only brightness options were 0 and 100%. But after the change, an option was added to have the switch behave like a dumb on/off switch, where the mechanical relay would connect/disconnect the load, and the dimming circuitry would not be involved at all.
I thought the dimming circuitry would be disabled due to the mention of that option fixing the scenario where someone has non-dimmable lights that flicker when powered by a dimmer switch even at 100% (as I mentioned earlier in this thread; I looked at the waveform coming out of the switch when it’s set as a dimmer at 100% brightness, and it’s still not a perfectly smooth sine wave; the switch still chops out part of the wave).
However, I tested the switch in Single Pole, On/Off, neutral mode, relay enabled (parameter 261, Disable Relay, “Click” Sound set to 0), and to my surprise, even though I hear the mechanical relay click, the dimming circuitry is still being used, and the switch isn’t putting out a clean sine wave. It’s almost exactly the same as when the switch is in Single Pole, dimmer mode at 100% brightness.
So unless I misunderstood the purpose of the firmware change, it doesn’t seem to be working as intended. While the relay makes the click sound, it’s not actually changing anything in terms of what the switch is doing. If someone has a load that requires the full, smooth, sine wave, it’s not going to work even with the switch in on/off relay enabled mode.