No light means on same breaker
Dimly lit means different breakers but same phase.
Fully lit means different breakers on different phases.
I’m guessing the “Dimly lit” condition would be rather more difficult for the unit to determine and the user to discern. Have you ever experienced it?
No I have not, but I was also not aware of that capability. Still, I've used it a lot in the 2+ years that I've owned it, and I gotta believe that I've plugged it into two breakers that were on the same phase by now. On or off is all I have ever noticed. Mind you, I still recommend it if you can run on two breakers.